NCCL 2.27.5-1

Improvements for GB200 systems
* Optimize the network performance by alternating the direction of the
  rings and the NIC to GPU assignment across communicators to limit
  unnecessary sharing.
* Fix the detection of C2C links in case GPU Direct RDMA is disabled
  between a GPU and a NIC.
* Fix PXN support on MNNVL systems, where NCCL would try (and fail) to
  share regular host memory across multiple nodes.
* Fix P2C (PXN over C2C), which is now preferred over regular PXN.  This
  support is currently preliminary and is disabled by default; use
  NCCL_PXN_C2C=1 to enable.

Further reduce the overheads of CUDA graph capturing, which increased in
NCCL 2.26.2 for large graphs.

Optimize the network performance on DGX B200 systems by adjusting the
bandwidths provided to the graph search algorithm.

Enable fp8 reductions in symmetric kernels on Blackwell with CUDA 12.8.

Restore the plugin name handling logic to make it possible to specify a
path to the plugin (Issue #1732).

Restore the ability to change NCCL_COLLNET_ENABLE during execution
(Issue #1741).

Add an example tuner plugin with CSV-based overrides.

Remove an x86 dependency from the example profiler.

ext-net/example/Makefile

@@ -3,15 +3,20 @@
 #
 # See LICENSE.txt for license information
 #
-NCCL_HOME:=../../build/
+.DEFAULT_GOAL: build
-CUDA_HOME:=/usr/local/cuda
+include ../../makefiles/common.mk
-INC:= -I$(NCCL_HOME)/include -I$(CUDA_HOME)/include -Inccl
+SRCDIR   ?= $(abspath ../..)
-PLUGIN_SO:=libnccl-net.so
+BUILDDIR ?= .
+NCCLDIR  := $(BUILDDIR)
 
-default: $(PLUGIN_SO)
+SRC_FILES := $(wildcard *.c)
 
-$(PLUGIN_SO): plugin.c
+build: ${BUILDDIR}/libnccl-net-example.so
-	$(CC) $(INC) -fPIC -shared -o $@ -Wl,-soname,$(PLUGIN_SO) $^
+
+${BUILDDIR}/libnccl-net-example.so: ${SRC_FILES}
+	@printf "Compiling  %-35s > %s\n" $< $@
+	@mkdir -p ${BUILDDIR}
+	$(CC) -Inccl -fPIC -shared -o $@ $^
 
 clean:
-	rm -f $(PLUGIN_SO)
+	rm -f ${BUILDDIR}/libnccl-net-example.so

ext-profiler/example/Makefile

@@ -3,14 +3,20 @@
 #
 # See LICENSE.txt for license information
 #
-NCCL_HOME := ../../build
+.DEFAULT_GOAL: build
-INC := -I$(NCCL_HOME)/include -I$(CUDA_HOME)/include -Inccl
+include ../../makefiles/common.mk
-PLUGIN_SO := libnccl-profiler.so
+SRCDIR   ?= $(abspath ../..)
+BUILDDIR ?= .
+NCCLDIR  := $(BUILDDIR)
 
-default: $(PLUGIN_SO)
+SRC_FILES := $(wildcard *.c)
 
-$(PLUGIN_SO): plugin.c event.c print_event.c
+build: ${BUILDDIR}/libnccl-profiler-example.so
-	$(CXX) $(INC) -g -fPIC -shared -o $@ -Wl,-soname,$(PLUGIN_SO) $^
+
+${BUILDDIR}/libnccl-profiler-example.so: ${SRC_FILES}
+	@printf "Compiling  %-35s > %s\n" $< $@
+	@mkdir -p ${BUILDDIR}
+	$(CC) -Inccl -fPIC -shared -o $@ $^
 
 clean:
-	rm -f $(PLUGIN_SO)
+	rm -f ${BUILDDIR}/libnccl-profiler-example.so

ext-profiler/example/plugin.c

@@ -12,7 +12,7 @@
 #include <sys/types.h>
 #include <sys/syscall.h>
 #include <unistd.h>
-#include <x86intrin.h>
+#include <time.h>
 #include "event.h"
 #include "print_event.h"
 
@@ -41,22 +41,10 @@ static struct proxyOp* detachPool;
 ncclDebugLogger_t logFn;
 #define INFO(FLAGS, ...) logFn(NCCL_LOG_INFO, (FLAGS), __func__, __LINE__, __VA_ARGS__)
 
-static double freq = -1;
-__hidden void calibrate() {
-  struct timeval tv;
-  gettimeofday(&tv, NULL);
-  uint64_t timeCycles = __rdtsc();
-  double time = - tv.tv_sec*1e6 - tv.tv_usec;
-  uint64_t total = 0ULL;
-  for (int i = 0; i < 10000; i++) total += __rdtsc();
-  gettimeofday(&tv, NULL);
-  timeCycles = __rdtsc() - timeCycles;
-  time += tv.tv_sec*1e6 + tv.tv_usec;
-  freq = timeCycles / time;
-}
-
 __hidden double gettime(void) {
-  return __rdtsc() / freq;
+  struct timespec t;
+  clock_gettime(CLOCK_MONOTONIC, &t);
+  return (t.tv_sec*1e6 + (t.tv_nsec*1e-3));
 }
 
 static pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;
@@ -98,8 +86,6 @@ __hidden ncclResult_t exampleProfilerInit(void** context, int* eActivationMask,
     // process address space.
     pid = getpid();
 
-    // calibrate and start timer
-    calibrate();
     startTime = gettime();
   }
   pthread_mutex_unlock(&lock);

ext-tuner/basic/Makefile

@@ -0,0 +1,23 @@
+#
+# Copyright (c) 2015-2019, NVIDIA CORPORATION. All rights reserved.
+#
+# See LICENSE.txt for license information
+#
+.DEFAULT_GOAL: build
+include ../../makefiles/common.mk
+SRCDIR   ?= $(abspath ../..)
+BUILDDIR ?= .
+NCCLDIR  := $(BUILDDIR)
+
+SRC_FILES := $(wildcard *.c)
+DST_DIR   := $(BUILDDIR)/test/unit/plugins
+
+build: ${BUILDDIR}/libnccl-tuner-basic.so
+
+${BUILDDIR}/libnccl-tuner-basic.so: ${SRC_FILES}
+	@printf "Compiling  %-35s > %s\n" $< $@
+	@mkdir -p ${BUILDDIR}
+	$(CC) -Inccl -fPIC -shared -o $@ $^
+
+clean:
+	rm -f ${BUILDDIR}/libnccl-tuner-basic.so

ext-tuner/basic/nccl/common.h

@@ -0,0 +1,15 @@
+/*************************************************************************
+ * Copyright (c) 2024, NVIDIA CORPORATION. All rights reserved.
+ *
+ * See LICENSE.txt for license information
+ ************************************************************************/
+
+#ifndef COMMON_H_
+#define COMMON_H_
+
+typedef enum {NCCL_LOG_NONE=0, NCCL_LOG_VERSION=1, NCCL_LOG_WARN=2, NCCL_LOG_INFO=3, NCCL_LOG_ABORT=4, NCCL_LOG_TRACE=5} ncclDebugLogLevel;
+typedef enum {NCCL_INIT=1, NCCL_COLL=2, NCCL_P2P=4, NCCL_SHM=8, NCCL_NET=16, NCCL_GRAPH=32, NCCL_TUNING=64, NCCL_ENV=128, NCCL_ALLOC=256, NCCL_CALL=512, NCCL_PROXY=1024, NCCL_NVLS=2048, NCCL_BOOTSTRAP=4096, NCCL_REG=8192, NCCL_ALL=~0} ncclDebugLogSubSys;
+
+typedef void (*ncclDebugLogger_t)(ncclDebugLogLevel level, unsigned long flags, const char *file, int line, const char *fmt, ...);
+
+#endif

ext-tuner/basic/nccl/err.h

@@ -0,0 +1,17 @@
+/*
+ * Copyright (c) 2017-2022, NVIDIA CORPORATION. All rights reserved.
+ */
+
+#ifndef NCCL_ERR_H_
+#define NCCL_ERR_H_
+
+/* Error type for plugins */
+typedef enum { ncclSuccess                 =  0,
+               ncclUnhandledCudaError      =  1,
+               ncclSystemError             =  2,
+               ncclInternalError           =  3,
+               ncclInvalidArgument         =  4,
+               ncclInvalidUsage            =  5,
+               ncclRemoteError             =  6 } ncclResult_t;
+
+#endif

ext-tuner/basic/nccl/tuner.h

@@ -0,0 +1,97 @@
+/*************************************************************************
+ * Copyright (c) 2023, NVIDIA CORPORATION. All rights reserved.
+ * Copyright (c) 2023, Meta Platforms, Inc. and affiliates.
+ *
+ * See LICENSE.txt for license information
+ ************************************************************************/
+
+#ifndef NCCL_TUNER_H_
+#define NCCL_TUNER_H_
+
+#include <stdint.h>
+#include <stdlib.h>
+
+#include "common.h"
+#include "err.h"
+
+#define NCCL_NUM_FUNCTIONS 5 // Send/Recv not included for now
+typedef enum {
+  ncclFuncBroadcast = 0,
+  ncclFuncReduce = 1,
+  ncclFuncAllGather = 2,
+  ncclFuncReduceScatter = 3,
+  ncclFuncAllReduce = 4,
+  ncclFuncSendRecv = 5,
+  ncclFuncSend = 6,
+  ncclFuncRecv = 7,
+  ncclNumFuncs = 8
+} ncclFunc_t;
+
+#define NCCL_NUM_ALGORITHMS 7 // Tree/Ring/CollNet*
+#define NCCL_ALGO_UNDEF -1
+#define NCCL_ALGO_TREE 0
+#define NCCL_ALGO_RING 1
+#define NCCL_ALGO_COLLNET_DIRECT 2
+#define NCCL_ALGO_COLLNET_CHAIN 3
+#define NCCL_ALGO_NVLS 4
+#define NCCL_ALGO_NVLS_TREE 5
+#define NCCL_ALGO_PAT 6
+
+#define NCCL_NUM_PROTOCOLS 3 // Simple/LL/LL128
+#define NCCL_PROTO_UNDEF -1
+#define NCCL_PROTO_LL 0
+#define NCCL_PROTO_LL128 1
+#define NCCL_PROTO_SIMPLE 2
+
+#define NCCL_ALGO_PROTO_IGNORE -1.0
+
+// API to be implemented by external tuner
+typedef struct {
+  // Name of the tuner
+  const char* name;
+
+  // Initializes tuner states.
+  // Inputs:
+  //   - nRanks: number of ranks in current communicator. Each communicator initialize its own tuner.
+  //   - nNodes: number of nodes in current communicator.
+  //   - logFunction: a logFunction can be useful to integrate logging together with NCCL core.
+  // Outputs:
+  //   - context: tuner context object
+  ncclResult_t (*init)(size_t nRanks, size_t nNodes, ncclDebugLogger_t logFunction, void **context);
+
+  // Gets info (algo, protocol, number of ctas and threads) for a given collective.
+  // Inputs:
+  //   - context: tuner context object
+  //   - collType: collective type , e.g., allreduce, allgather…
+  //   - nBytes: collective size in bytes
+  //   - numPipeOps: number of operations in the group
+  //   - numAlgo: number of algorithms in collCostTable
+  //   - numProto: number of protocols in collCostTable
+  //   - regBuff: can register user buffer
+  //
+  // Outputs:
+  //   - nChannels: number of channels (hence SMs) to be used.
+  //
+  // InOut:
+  //   - collCostTable: collective cost table, generated by NCCL core, containing algo|proto|time entries for collType.
+  //                    NCCL core sets ignored algo/proto cost table entries to -1.0 (NCCL_ALGO_PROTO_IGNORE).
+  //
+  // If getCollInfo() does not return ncclSuccess, NCCL will fall back to the
+  // default tuning for the given collective.
+  // Also, the plugin is allowed to not set any output, or set only the
+  // algorithm and protocol, but not only the algorithm or only the protocol.
+  // Unset fields will be set automatically by NCCL.
+  ncclResult_t (*getCollInfo)(void* context, ncclFunc_t collType, size_t nBytes,
+                              int numPipeOps, float** collCostTable, int numAlgo, int numProto,
+                              int regBuff, int* nChannels);
+
+  // Terminates the plugin and cleans up any resources that the plugin allocated.
+  // context: tuner context object
+  ncclResult_t (*destroy)(void* context);
+} ncclTuner_v4_t;
+
+typedef ncclTuner_v4_t ncclTuner_t;
+
+#define NCCL_TUNER_PLUGIN_SYMBOL "ncclTunerPlugin_v4"
+
+#endif

ext-tuner/basic/plugin.c

@@ -0,0 +1,34 @@
+/*************************************************************************
+ * Copyright (c) 2015-2019, NVIDIA CORPORATION. All rights reserved.
+ *
+ * See LICENSE.txt for license information
+ ************************************************************************/
+
+#include "tuner.h"
+
+#define __hidden __attribute__ ((visibility("hidden")))
+
+__hidden ncclResult_t pluginInit(size_t nRanks, size_t nNodes, ncclDebugLogger_t logFunction, void **context) { return ncclSuccess; }
+
+__hidden ncclResult_t pluginGetCollInfo(void* context, ncclFunc_t collType, size_t nBytes,
+                              int numPipeOps, float** collCostTable, int numAlgo, int numProto,
+                              int regBuff, int* nChannels) {
+  // Update NCCL core generated cost table. Updated table will be evaluated by NCCL to pick the best algo/proto combo
+  float (*table)[NCCL_NUM_PROTOCOLS] = (float (*)[NCCL_NUM_PROTOCOLS])collCostTable;
+  if (table[NCCL_ALGO_RING][NCCL_PROTO_SIMPLE] != NCCL_ALGO_PROTO_IGNORE) {
+    table[NCCL_ALGO_RING][NCCL_PROTO_SIMPLE] = 0.0;
+  }
+  *nChannels = 1;
+  return ncclSuccess;
+}
+
+__hidden ncclResult_t pluginDestroy(void* context) { return ncclSuccess; }
+
+#define PLUGIN_NAME "Basic"
+
+const ncclTuner_v4_t ncclTunerPlugin_v4 = {
+  .name = PLUGIN_NAME,
+  .init = pluginInit,
+  .getCollInfo = pluginGetCollInfo,
+  .destroy = pluginDestroy
+};

ext-tuner/example/Makefile

@@ -3,15 +3,53 @@
 #
 # See LICENSE.txt for license information
 #
-NCCL_HOME:=../../build/
-CUDA_HOME:=/usr/local/cuda
-INC:= -I$(NCCL_HOME)/include -I$(CUDA_HOME)/include -Inccl
-PLUGIN_SO:=libnccl-tuner.so
 
-default: $(PLUGIN_SO)
+.DEFAULT_GOAL: build
+PLUGIN_SO:=libnccl-tuner-example.so
+include ../../makefiles/common.mk
+SRCDIR   ?= $(abspath ../..)
+BUILDDIR ?= .
+NCCLDIR  := $(BUILDDIR)
 
-$(PLUGIN_SO): plugin.c
+SRC_FILES := $(wildcard *.c)
-	$(CC) $(INC) -fPIC -shared -o $@ -Wl,-soname,$(PLUGIN_SO) $^
+DST_DIR   := $(BUILDDIR)/test/unit/plugins
+
+default: ${BUILDDIR}/$(PLUGIN_SO)
+
+build: ${BUILDDIR}/$(PLUGIN_SO)
+
+${BUILDDIR}/$(PLUGIN_SO): plugin.c
+	@printf "Compiling  %-35s > %s\n" $< $@
+	@mkdir -p ${BUILDDIR}
+	$(CC) -Inccl $(INC) -fPIC -shared -o $@ -Wl,-soname,$(PLUGIN_SO) $^
+
+# Test targets - delegate to test directory
+test:
+	$(MAKE) -C test test TEST_CASE=$(TEST_CASE)
+
+test-verbose:
+	$(MAKE) -C test test-verbose TEST_CASE=$(TEST_CASE)
+
+# Build tests
+test-build:
+	$(MAKE) -C test all
+
+# Optimize configurations from performance data
+optimize-config:
+	@if [ -z "$(CSV_FILE)" ]; then \
+		echo "Usage: make optimize-config CSV_FILE=path/to/data.csv [OUTPUT=config.conf] [METRIC=latency_us]"; \
+		echo "Example: make optimize-config CSV_FILE=scripts/sample_performance_data.csv"; \
+		exit 1; \
+	fi
+	python3 scripts/optimize_config.py $(CSV_FILE) \
+		$(if $(OUTPUT),-o $(OUTPUT)) \
+		$(if $(METRIC),-m $(METRIC)) \
+		$(if $(SIZE_RANGES),--size-ranges $(SIZE_RANGES)) \
+		$(if $(DRY_RUN),--dry-run) \
+		$(if $(NO_HEADER),--no-header)
 
 clean:
-	rm -f $(PLUGIN_SO)
+	rm -f ${BUILDDIR}/$(PLUGIN_SO)
+	$(MAKE) -C test clean
+
+.PHONY: test test-verbose test-build optimize-config clean

ext-tuner/example/README.md

@@ -0,0 +1,164 @@
+# NCCL Example Tuner Plugin
+
+This example plugin shows a practical example of a CSV file-based tuning approach, allowing selective overrides for tuning parameters based on all tuning inputs without recompiling.
+
+## Features
+
+- **File-based Configuration**: Read tuning parameters from a CSV configuration file
+- **Size-based Tuning**: Specify different configurations based on message size ranges
+- **Dimension-aware Tuning**: Match configurations based on number of nodes and ranks
+- **Optional Channels Configuration**: Set specific channel counts or use -1 to keep NCCL's default
+- **Environment Variable Support**: Specify config file location via `NCCL_TUNER_CONFIG_FILE`
+- **Fallback Behavior**: Gracefully handles missing config files and invalid entries
+
+## Building
+
+```bash
+make
+```
+
+This will create `libnccl-tuner-example.so` that can be loaded by NCCL.
+
+## Configuration File Format
+
+The configuration file uses CSV (Comma-Separated Values) format with one configuration per line:
+
+```
+collective_type,min_bytes,max_bytes,algorithm,protocol,channels,nNodes,nRanks,numPipeOps,regBuff
+```
+
+### Parameters
+
+- **collective_type**: The collective operation type
+  - `broadcast`, `reduce`, `allgather`, `reducescatter`, `allreduce`
+
+- **min_bytes/max_bytes**: The message size range (in bytes) for which this config applies
+  - Use `0` for minimum and `4294967295` for maximum (covers all sizes)
+
+- **algorithm**: The NCCL algorithm to use
+  - `tree`, `ring`, `collnet_direct`, `collnet_chain`, `nvls`, `nvls_tree`, `pat`
+
+- **protocol**: The NCCL protocol to use
+  - `ll`, `ll128`, `simple`
+
+- **channels**: Number of channels (SMs) to use
+  - Use a positive integer to specify exact channel count
+  - Use `-1` to keep NCCL's default channel selection
+
+- **nNodes**: Number of nodes to match
+  - Use a positive integer to match specific node count
+  - Use `-1` to match any number of nodes
+
+- **nRanks**: Number of ranks to match
+  - Use a positive integer to match specific rank count
+  - Use `-1` to match any number of ranks
+
+- **numPipeOps**: Number of pipeline operations to match (optional)
+  - Use a positive integer to match specific pipeline operation count
+  - Use `-1` to match any number of pipeline operations
+  - If omitted, configuration will match any numPipeOps value
+
+- **regBuff**: Whether user buffer can be registered (optional)
+  - Use `0` to match only non-registered buffers
+  - Use `1` to match only registered buffers
+  - Use `-1` to match either registered or non-registered buffers
+  - If omitted, configuration will match any regBuff value
+
+### Example Configuration
+
+```csv
+# Single-node, small allreduce: use tree algorithm, registered buffers only
+allreduce,0,65536,tree,simple,2,1,-1,-1,1
+
+# 4-node, 32-rank setup: medium allreduce, single pipeline op, non-registered buffers
+allreduce,65537,1048576,ring,simple,4,4,32,1,0
+
+# Any topology: large allreduce with LL128, multiple pipeline ops, any buffer type
+allreduce,1048577,4294967295,ring,ll128,-1,-1,-1,4,-1
+
+# Single-node broadcast: prefer tree, any pipeOps, registered buffers (backward compatible)
+broadcast,0,32768,tree,simple,-1,1,-1
+
+# Multi-node broadcast: optimized for non-registered buffers, single pipeline op
+broadcast,32769,4294967295,ring,simple,2,-1,-1,1,0
+```
+
+Comments start with `#` and empty lines are ignored. The CSV format makes it easy to edit configurations in spreadsheet applications like Excel, Google Sheets, or LibreOffice Calc.
+
+### Backward Compatibility
+
+Configurations without the numPipeOps and/or regBuff parameters are fully supported:
+- 8 fields: matches any numPipeOps and regBuff values
+- 9 fields: matches any regBuff value
+- 10 fields: full parameter specification
+
+This ensures existing configuration files continue to work without modification.
+
+## Usage
+
+### Method 1: Default Config File
+Place your configuration in `nccl_tuner.conf` in the current working directory.
+
+### Method 2: Environment Variable
+Set the `NCCL_TUNER_CONFIG_FILE` environment variable to specify the config file path:
+
+```bash
+export NCCL_TUNER_CONFIG_FILE=/path/to/your/tuner.conf
+export LD_LIBRARY_PATH=/path/to/plugin:$LD_LIBRARY_PATH
+mpirun -np 4 your_nccl_application
+```
+
+## Editing Configuration Files
+
+### Generating Configuration Files from Raw Data
+
+A python script to generate valid CSV configs has been provided. [Using optimize_config.py](scripts/README.md).
+
+### Spreadsheet Tips:
+- Use column headers: `collective_type,min_bytes,max_bytes,algorithm,protocol,channels,nNodes,nRanks,numPipeOps,regBuff`
+- Save as CSV format (not Excel format) for the plugin to read
+- Use data validation to prevent typos in algorithm/protocol names
+
+## Logging
+
+The plugin uses NCCL's logging system. To see tuner-related messages:
+
+```bash
+export NCCL_DEBUG=INFO
+```
+
+This will show when configurations are loaded and applied, including the topology information.
+
+For detailed debugging output during tuning decisions:
+
+```bash
+export NCCL_DEBUG=TRACE
+```
+
+This will show verbose information about which configurations are being evaluated and matched.
+
+## Dimension Matching
+
+Configurations are only applied when the topology matches:
+
+- **Exact Match**: Configuration specifies `nNodes=4,nRanks=32`, only applied when communicator has exactly 4 nodes and 32 ranks
+- **Wildcard Nodes**: Configuration specifies `nNodes=-1,nRanks=8`, applied to any topology with exactly 8 ranks
+- **Wildcard Ranks**: Configuration specifies `nNodes=2,nRanks=-1`, applied to any 2-node topology regardless of ranks per node
+- **Wildcard Both**: Configuration specifies `nNodes=-1,nRanks=-1`, applied to any topology
+
+This allows you to create specialized configurations for different cluster setups while maintaining flexibility.
+
+## Default Behavior
+
+If no configuration file is found or no matching configuration exists for a collective operation, the plugin falls back to preferring the ring algorithm with simple protocol. All configured algorithm/protocol combinations are given a low cost (0.0) to make them preferred by NCCL's selection logic.
+
+When channels is set to `-1`, NCCL's default channel selection logic is preserved, allowing the system to automatically determine the optimal number of channels based on hardware and message size.
+
+## Troubleshooting
+
+1. **Config file not found**: Check the file path and permissions
+2. **Configurations not applied**: Verify the collective type, size ranges, algorithm/protocol names, and topology parameters
+3. **Plugin not loaded**: Ensure `LD_LIBRARY_PATH` includes the plugin directory
+4. **No effect on performance**: Check that NCCL is actually using the tuner plugin with `NCCL_DEBUG=INFO`
+5. **Topology mismatch**: Verify that nNodes and nRanks match your actual setup, or use -1 for wildcards
+6. **CSV parsing errors**: Ensure no spaces after commas, or quote fields containing spaces

ext-tuner/example/nccl_tuner.conf

@@ -0,0 +1,45 @@
+# NCCL Tuner Configuration File (CSV Format)
+# Format: collective_type,min_bytes,max_bytes,algorithm,protocol,channels,nNodes,nRanks,numPipeOps,regBuff
+#
+# Collective types: broadcast, reduce, allgather, reducescatter, allreduce
+# Algorithms: tree, ring, collnet_direct, collnet_chain, nvls, nvls_tree, pat
+# Protocols: ll, ll128, simple
+# Channels: number of channels to use, or -1 to keep default
+# nNodes: number of nodes to match, or -1 for any number of nodes
+# nRanks: number of ranks to match, or -1 for any number of ranks
+# numPipeOps: number of pipeline operations to match, or -1 for any number (optional)
+# regBuff: whether user buffer can be registered (0=no, 1=yes, -1=any) (optional)
+#
+# Note: numPipeOps and regBuff parameters are optional - configurations without them will match any value
+#
+# Examples:
+
+# For single-node configurations with registered buffers
+# Small allreduce operations on single node - use tree algorithm, registered buffers
+allreduce,0,65536,tree,simple,2,1,-1,-1,1
+
+# For multi-node configurations with 4 nodes, 32 total ranks, single pipeline op, non-registered buffers
+# Medium allreduce operations - use ring algorithm
+allreduce,65537,1048576,ring,simple,4,4,32,1,0
+
+# For any topology - large allreduce operations with LL128 protocol, multiple pipeline ops, any buffer type
+allreduce,1048577,4294967295,ring,ll128,-1,-1,-1,4,-1
+
+# Broadcast operations - different configs for different topologies, pipeline complexity, and buffer types
+# Single node broadcast - prefer tree, any pipeOps, registered buffers only
+broadcast,0,32768,tree,simple,-1,1,-1,-1,1
+
+# Multi-node broadcast with single pipeline operation, non-registered buffers - use ring
+broadcast,32769,4294967295,ring,simple,2,-1,-1,1,0
+
+# AllGather operations - optimized for 2-node configurations, any pipeOps, any buffer type
+allgather,0,4294967295,ring,simple,4,2,-1
+
+# ReduceScatter operations
+# Small messages on single node, single pipeline op, registered buffers
+reducescatter,0,131072,tree,simple,2,1,-1,1,1
+# Large messages on any topology, multiple pipeline ops, non-registered buffers
+reducescatter,131073,4294967295,ring,simple,-1,-1,-1,2,0
+
+# Reduce operations - any topology, keep default channels, any pipeOps, any buffer type
+reduce,0,4294967295,tree,simple,-1,-1,-1

ext-tuner/example/plugin.c

@@ -5,24 +5,443 @@
  ************************************************************************/
 
 #include "tuner.h"
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
 
 #define __hidden __attribute__ ((visibility("hidden")))
+#define MAX_LINE_LENGTH 256
 
-__hidden ncclResult_t pluginInit(size_t nRanks, size_t nNodes, ncclDebugLogger_t logFunction, void **context) { return ncclSuccess; }
+// CSV field indices for configuration parsing
+// Format: colltype,minbytes,maxbytes,algorithm,protocol,channels,nNodes,nRanks,numPipeOps,regBuff
+#define CONFIG_FIELD_COLLTYPE     0
+#define CONFIG_FIELD_MINBYTES     1
+#define CONFIG_FIELD_MAXBYTES     2
+#define CONFIG_FIELD_ALGORITHM    3
+#define CONFIG_FIELD_PROTOCOL     4
+#define CONFIG_FIELD_CHANNELS     5
+#define CONFIG_FIELD_NNODES       6
+#define CONFIG_FIELD_NRANKS       7
+#define CONFIG_FIELD_PIPEOPS      8  // Optional field
+#define CONFIG_FIELD_REGBUFF      9  // Optional field
+
+// Field count constants
+#define CONFIG_FIELDS_REQUIRED    8   // Minimum required fields (up to nRanks)
+#define CONFIG_FIELDS_WITH_PIPEOPS 9  // Fields including numPipeOps
+#define CONFIG_FIELDS_WITH_REGBUFF 10 // Fields including both numPipeOps and regBuff
+#define CONFIG_FIELDS_MAX         10  // Maximum number of fields supported
+
+typedef struct {
+  ncclFunc_t collType;
+  size_t minBytes;
+  size_t maxBytes;
+  int algorithm;
+  int protocol;
+  int nChannels;
+  int nNodes;
+  int nRanks;
+  int numPipeOps;
+  int regBuff;
+} TuningConfig;
+
+typedef struct {
+  TuningConfig* configs;  // Changed from static array to dynamic pointer
+  int numConfigs;
+  int maxConfigs;         // Added to track allocated size
+  size_t nRanks;
+  size_t nNodes;
+  ncclDebugLogger_t logFunction;
+} TunerContext;
+
+// Parse collective type from string
+static ncclFunc_t parseCollType(const char* str) {
+  if (strcmp(str, "broadcast") == 0) return ncclFuncBroadcast;
+  if (strcmp(str, "reduce") == 0) return ncclFuncReduce;
+  if (strcmp(str, "allgather") == 0) return ncclFuncAllGather;
+  if (strcmp(str, "reducescatter") == 0) return ncclFuncReduceScatter;
+  if (strcmp(str, "allreduce") == 0) return ncclFuncAllReduce;
+  return ncclFuncAllReduce; // default
+}
+
+// Convert collective type to string
+static const char* collTypeToString(ncclFunc_t collType) {
+  switch (collType) {
+    case ncclFuncBroadcast: return "broadcast";
+    case ncclFuncReduce: return "reduce";
+    case ncclFuncAllGather: return "allgather";
+    case ncclFuncReduceScatter: return "reducescatter";
+    case ncclFuncAllReduce: return "allreduce";
+    default: return "unknown";
+  }
+}
+
+// Parse algorithm from string
+static int parseAlgorithm(const char* str) {
+  if (strcmp(str, "tree") == 0) return NCCL_ALGO_TREE;
+  if (strcmp(str, "ring") == 0) return NCCL_ALGO_RING;
+  if (strcmp(str, "collnet_direct") == 0) return NCCL_ALGO_COLLNET_DIRECT;
+  if (strcmp(str, "collnet_chain") == 0) return NCCL_ALGO_COLLNET_CHAIN;
+  if (strcmp(str, "nvls") == 0) return NCCL_ALGO_NVLS;
+  if (strcmp(str, "nvls_tree") == 0) return NCCL_ALGO_NVLS_TREE;
+  if (strcmp(str, "pat") == 0) return NCCL_ALGO_PAT;
+  return NCCL_ALGO_RING; // default
+}
+
+// Convert algorithm to string
+static const char* algorithmToString(int algorithm) {
+  switch (algorithm) {
+    case NCCL_ALGO_TREE: return "tree";
+    case NCCL_ALGO_RING: return "ring";
+    case NCCL_ALGO_COLLNET_DIRECT: return "collnet_direct";
+    case NCCL_ALGO_COLLNET_CHAIN: return "collnet_chain";
+    case NCCL_ALGO_NVLS: return "nvls";
+    case NCCL_ALGO_NVLS_TREE: return "nvls_tree";
+    case NCCL_ALGO_PAT: return "pat";
+    default: return "unknown";
+  }
+}
+
+// Parse protocol from string
+static int parseProtocol(const char* str) {
+  if (strcmp(str, "ll") == 0) return NCCL_PROTO_LL;
+  if (strcmp(str, "ll128") == 0) return NCCL_PROTO_LL128;
+  if (strcmp(str, "simple") == 0) return NCCL_PROTO_SIMPLE;
+  return NCCL_PROTO_SIMPLE; // default
+}
+
+// Convert protocol to string
+static const char* protocolToString(int protocol) {
+  switch (protocol) {
+    case NCCL_PROTO_LL: return "ll";
+    case NCCL_PROTO_LL128: return "ll128";
+    case NCCL_PROTO_SIMPLE: return "simple";
+    default: return "unknown";
+  }
+}
+
+// Helper function to count valid configuration lines in file
+static int countConfigLines(const char* filename) {
+  FILE* file = fopen(filename, "r");
+  if (!file) {
+    return 0;
+  }
+
+  char line[MAX_LINE_LENGTH];
+  int count = 0;
+
+  while (fgets(line, sizeof(line), file)) {
+    // Skip comments and empty lines
+    if (line[0] == '#' || line[0] == '\n') continue;
+
+    // Remove trailing newline
+    line[strcspn(line, "\n")] = 0;
+
+    // Check if line has content
+    if (strlen(line) > 0) {
+      count++;
+    }
+  }
+
+  fclose(file);
+  return count;
+}
+
+// Load configuration from file
+static ncclResult_t loadConfig(TunerContext* ctx, const char* filename) {
+  FILE* file = fopen(filename, "r");
+  if (!file) {
+    if (ctx->logFunction) {
+      ctx->logFunction(NCCL_LOG_INFO, NCCL_TUNING, __FILE__, __LINE__,
+                       "TUNER/ExamplePlugin: Config file %s not found, using defaults", filename);
+    }
+    return ncclSuccess; // Not finding config file is not an error
+  }
+
+  // First pass: count valid configuration lines
+  int configCount = countConfigLines(filename);
+  if (configCount == 0) {
+    if (ctx->logFunction) {
+      ctx->logFunction(NCCL_LOG_INFO, NCCL_TUNING, __FILE__, __LINE__,
+                       "TUNER/ExamplePlugin: No valid configurations found in %s", filename);
+    }
+    fclose(file);
+    return ncclSuccess;
+  }
+
+  // Allocate memory for configurations based on actual count
+  ctx->configs = (TuningConfig*)malloc(configCount * sizeof(TuningConfig));
+  if (!ctx->configs) {
+    if (ctx->logFunction) {
+      ctx->logFunction(NCCL_LOG_INFO, NCCL_TUNING, __FILE__, __LINE__,
+                       "TUNER/ExamplePlugin: Failed to allocate memory for %d configurations", configCount);
+    }
+    fclose(file);
+    return ncclSystemError;
+  }
+
+  ctx->maxConfigs = configCount;
+  ctx->numConfigs = 0;
+
+  if (ctx->logFunction) {
+    ctx->logFunction(NCCL_LOG_INFO, NCCL_TUNING, __FILE__, __LINE__,
+                     "TUNER/ExamplePlugin: Allocated memory for %d configurations", configCount);
+  }
+
+  // Reset file pointer to beginning
+  fseek(file, 0, SEEK_SET);
+
+  char line[MAX_LINE_LENGTH];
+
+  while (fgets(line, sizeof(line), file) && ctx->numConfigs < ctx->maxConfigs) {
+    // Skip comments and empty lines
+    if (line[0] == '#' || line[0] == '\n') continue;
+
+    // Remove trailing newline
+    line[strcspn(line, "\n")] = 0;
+
+    // Parse CSV format: colltype,minbytes,maxbytes,algorithm,protocol,channels,nNodes,nRanks,numPipeOps,regBuff
+    char* token;
+    char* tokens[CONFIG_FIELDS_MAX];
+    int tokenCount = 0;
+
+    // Make a copy of the line for tokenizing
+    char lineCopy[MAX_LINE_LENGTH];
+    strncpy(lineCopy, line, sizeof(lineCopy));
+    lineCopy[sizeof(lineCopy) - 1] = '\0';
+
+    // Tokenize by comma
+    token = strtok(lineCopy, ",");
+    while (token != NULL && tokenCount < CONFIG_FIELDS_MAX) {
+      // Trim whitespace
+      while (*token == ' ' || *token == '\t') token++;
+      char* end = token + strlen(token) - 1;
+      while (end > token && (*end == ' ' || *end == '\t')) {
+        *end = '\0';
+        end--;
+      }
+      tokens[tokenCount++] = token;
+      token = strtok(NULL, ",");
+    }
+
+    // Validate field count: support required fields (8), with pipeOps (9), or with regBuff (10)
+    if (tokenCount >= CONFIG_FIELDS_REQUIRED && tokenCount <= CONFIG_FIELDS_MAX) {
+      TuningConfig* config = &ctx->configs[ctx->numConfigs];
+      config->collType = parseCollType(tokens[CONFIG_FIELD_COLLTYPE]);
+      config->minBytes = (size_t)strtoull(tokens[CONFIG_FIELD_MINBYTES], NULL, 10);
+      config->maxBytes = (size_t)strtoull(tokens[CONFIG_FIELD_MAXBYTES], NULL, 10);
+      config->algorithm = parseAlgorithm(tokens[CONFIG_FIELD_ALGORITHM]);
+      config->protocol = parseProtocol(tokens[CONFIG_FIELD_PROTOCOL]);
+      config->nChannels = atoi(tokens[CONFIG_FIELD_CHANNELS]);
+      config->nNodes = atoi(tokens[CONFIG_FIELD_NNODES]);
+      config->nRanks = atoi(tokens[CONFIG_FIELD_NRANKS]);
+
+      // numPipeOps is optional (9th field, index 8)
+      if (tokenCount >= CONFIG_FIELDS_WITH_PIPEOPS) {
+        config->numPipeOps = atoi(tokens[CONFIG_FIELD_PIPEOPS]);
+      } else {
+        config->numPipeOps = -1; // -1 means match any numPipeOps
+      }
+
+      // regBuff is optional (10th field, index 9)
+      if (tokenCount >= CONFIG_FIELDS_WITH_REGBUFF) {
+        config->regBuff = atoi(tokens[CONFIG_FIELD_REGBUFF]);
+      } else {
+        config->regBuff = -1; // -1 means match any regBuff value
+      }
+
+      ctx->numConfigs++;
+
+      if (ctx->logFunction) {
+        if (config->numPipeOps == -1 && config->regBuff == -1) {
+          ctx->logFunction(NCCL_LOG_INFO, NCCL_TUNING, __FILE__, __LINE__,
+                           "TUNER/ExamplePlugin: Loaded config: %s [%zu-%zu] %s/%s channels=%d nodes=%d ranks=%d pipeOps=any regBuff=any",
+                           tokens[CONFIG_FIELD_COLLTYPE], config->minBytes, config->maxBytes,
+                           tokens[CONFIG_FIELD_ALGORITHM], tokens[CONFIG_FIELD_PROTOCOL],
+                           config->nChannels, config->nNodes, config->nRanks);
+        } else if (config->regBuff == -1) {
+          ctx->logFunction(NCCL_LOG_INFO, NCCL_TUNING, __FILE__, __LINE__,
+                           "TUNER/ExamplePlugin: Loaded config: %s [%zu-%zu] %s/%s channels=%d nodes=%d ranks=%d pipeOps=%d regBuff=any",
+                           tokens[CONFIG_FIELD_COLLTYPE], config->minBytes, config->maxBytes,
+                           tokens[CONFIG_FIELD_ALGORITHM], tokens[CONFIG_FIELD_PROTOCOL],
+                           config->nChannels, config->nNodes, config->nRanks, config->numPipeOps);
+        } else if (config->numPipeOps == -1) {
+          ctx->logFunction(NCCL_LOG_INFO, NCCL_TUNING, __FILE__, __LINE__,
+                           "TUNER/ExamplePlugin: Loaded config: %s [%zu-%zu] %s/%s channels=%d nodes=%d ranks=%d pipeOps=any regBuff=%d",
+                           tokens[CONFIG_FIELD_COLLTYPE], config->minBytes, config->maxBytes,
+                           tokens[CONFIG_FIELD_ALGORITHM], tokens[CONFIG_FIELD_PROTOCOL],
+                           config->nChannels, config->nNodes, config->nRanks, config->regBuff);
+        } else {
+          ctx->logFunction(NCCL_LOG_INFO, NCCL_TUNING, __FILE__, __LINE__,
+                           "TUNER/ExamplePlugin: Loaded config: %s [%zu-%zu] %s/%s channels=%d nodes=%d ranks=%d pipeOps=%d regBuff=%d",
+                           tokens[CONFIG_FIELD_COLLTYPE], config->minBytes, config->maxBytes,
+                           tokens[CONFIG_FIELD_ALGORITHM], tokens[CONFIG_FIELD_PROTOCOL],
+                           config->nChannels, config->nNodes, config->nRanks, config->numPipeOps, config->regBuff);
+        }
+      }
+    }
+  }
+
+  fclose(file);
+  if (ctx->logFunction) {
+    ctx->logFunction(NCCL_LOG_INFO, NCCL_TUNING, __FILE__, __LINE__,
+                     "TUNER/ExamplePlugin: Loaded %d tuning configurations from %s", ctx->numConfigs, filename);
+  }
+  return ncclSuccess;
+}
+
+__hidden ncclResult_t pluginInit(size_t nRanks, size_t nNodes, ncclDebugLogger_t logFunction, void **context) {
+  TunerContext* ctx = (TunerContext*)malloc(sizeof(TunerContext));
+  if (!ctx) return ncclSystemError;
+
+  ctx->configs = NULL;     // Initialize to NULL
+  ctx->numConfigs = 0;
+  ctx->maxConfigs = 0;     // Initialize to 0
+  ctx->nRanks = nRanks;
+  ctx->nNodes = nNodes;
+  ctx->logFunction = logFunction;
+
+  if (logFunction) {
+    logFunction(NCCL_LOG_INFO, NCCL_TUNING, __FILE__, __LINE__,
+                "TUNER/ExamplePlugin: Initializing tuner for %zu nodes, %zu ranks", nNodes, nRanks);
+  }
+
+  // Try to load config file from environment variable or default location
+  const char* configFile = getenv("NCCL_TUNER_CONFIG_FILE");
+  if (!configFile) {
+    configFile = "nccl_tuner.conf"; // default config file name
+  }
+
+  ncclResult_t result = loadConfig(ctx, configFile);
+  if (result != ncclSuccess) {
+    if (ctx->configs) {
+      free(ctx->configs);  // Clean up allocated memory on error
+    }
+    free(ctx);
+    return result;
+  }
+
+  *context = ctx;
+  return ncclSuccess;
+}
 
 __hidden ncclResult_t pluginGetCollInfo(void* context, ncclFunc_t collType, size_t nBytes,
                               int numPipeOps, float** collCostTable, int numAlgo, int numProto,
                               int regBuff, int* nChannels) {
-  // Update NCCL core generated cost table. Updated table will be evaluated by NCCL to pick the best algo/proto combo
+  TunerContext* ctx = (TunerContext*)context;
-  float (*table)[NCCL_NUM_PROTOCOLS] = (float (*)[NCCL_NUM_PROTOCOLS])collCostTable;
+  if (!ctx) return ncclInternalError;
-  if (table[NCCL_ALGO_RING][NCCL_PROTO_SIMPLE] != NCCL_ALGO_PROTO_IGNORE) {
+
-    table[NCCL_ALGO_RING][NCCL_PROTO_SIMPLE] = 0.0;
+  // Default channels
-  }
   *nChannels = 1;
+
+  if (ctx->logFunction) {
+    ctx->logFunction(NCCL_LOG_TRACE, NCCL_TUNING, __FILE__, __LINE__,
+                     "TUNER/ExamplePlugin: pluginGetCollInfo called - collType=%s, nBytes=%zu, numPipeOps=%d, regBuff=%d, numConfigs=%d",
+                     collTypeToString(collType), nBytes, numPipeOps, regBuff, ctx->numConfigs);
+  }
+
+  // Look for matching configuration
+  for (int i = 0; i < ctx->numConfigs; i++) {
+    TuningConfig* config = &ctx->configs[i];
+
+    if (ctx->logFunction) {
+      ctx->logFunction(NCCL_LOG_TRACE, NCCL_TUNING, __FILE__, __LINE__,
+                       "TUNER/ExamplePlugin: Checking config %d - collType=%s, minBytes=%zu, maxBytes=%zu, algo=%s, proto=%s, nNodes=%d, nRanks=%d, numPipeOps=%d, regBuff=%d",
+                       i, collTypeToString(config->collType), config->minBytes, config->maxBytes, algorithmToString(config->algorithm), protocolToString(config->protocol),
+                       config->nNodes, config->nRanks, config->numPipeOps, config->regBuff);
+    }
+
+    // Check if this config matches the current collective, size range, topology, pipeline ops, and regBuff
+    if (config->collType == collType &&
+        nBytes >= config->minBytes &&
+        nBytes <= config->maxBytes &&
+        (config->nNodes == -1 || config->nNodes == (int)ctx->nNodes) &&
+        (config->nRanks == -1 || config->nRanks == (int)ctx->nRanks) &&
+        (config->numPipeOps == -1 || config->numPipeOps == numPipeOps) &&
+        (config->regBuff == -1 || config->regBuff == regBuff)) {
+
+      if (ctx->logFunction) {
+        ctx->logFunction(NCCL_LOG_TRACE, NCCL_TUNING, __FILE__, __LINE__,
+                         "TUNER/ExamplePlugin: Config matches. Applying algo=%s, proto=%s, channels=%d",
+                         algorithmToString(config->algorithm), protocolToString(config->protocol), config->nChannels);
+      }
+
+      // Check bounds
+      if (config->algorithm < numAlgo && config->protocol < numProto) {
+        if (collCostTable[config->algorithm][config->protocol] != NCCL_ALGO_PROTO_IGNORE) {
+          if (ctx->logFunction) {
+            ctx->logFunction(NCCL_LOG_TRACE, NCCL_TUNING, __FILE__, __LINE__,
+                             "TUNER/ExamplePlugin: Setting cost table[%s][%s] (%p) = 0.0 (was %.1f)",
+                             algorithmToString(config->algorithm), protocolToString(config->protocol),
+                             &collCostTable[config->algorithm][config->protocol], collCostTable[config->algorithm][config->protocol]);
+          }
+          collCostTable[config->algorithm][config->protocol] = 0.0; // Set low cost to prefer this configuration
+
+          // Only override channels if not set to -1 (keep default)
+          if (config->nChannels != -1) {
+            *nChannels = config->nChannels;
+          }
+
+          if (ctx->logFunction) {
+            if (config->nChannels == -1) {
+              ctx->logFunction(NCCL_LOG_INFO, NCCL_TUNING, __FILE__, __LINE__,
+                               "TUNER/ExamplePlugin: Applied config for collType=%s, bytes=%zu, pipeOps=%d, regBuff=%d: algo=%s, proto=%s, channels=default (nodes=%d, ranks=%d)",
+                               collTypeToString(config->collType), nBytes, numPipeOps, regBuff, algorithmToString(config->algorithm), protocolToString(config->protocol),
+                               config->nNodes, config->nRanks);
+            } else {
+              ctx->logFunction(NCCL_LOG_INFO, NCCL_TUNING, __FILE__, __LINE__,
+                               "TUNER/ExamplePlugin: Applied config for collType=%s, bytes=%zu, pipeOps=%d, regBuff=%d: algo=%s, proto=%s, channels=%d (nodes=%d, ranks=%d)",
+                               collTypeToString(config->collType), nBytes, numPipeOps, regBuff, algorithmToString(config->algorithm), protocolToString(config->protocol),
+                               config->nChannels, config->nNodes, config->nRanks);
+            }
+          }
+          return ncclSuccess;
+        } else {
+          if (ctx->logFunction) {
+            ctx->logFunction(NCCL_LOG_INFO, NCCL_TUNING, __FILE__, __LINE__,
+                             "TUNER/ExamplePlugin: Algorithm/protocol combination [%s][%s] is marked as IGNORE",
+                             algorithmToString(config->algorithm), protocolToString(config->protocol));
+          }
+        }
+      } else {
+        if (ctx->logFunction) {
+          ctx->logFunction(NCCL_LOG_INFO, NCCL_TUNING, __FILE__, __LINE__,
+                           "TUNER/ExamplePlugin: Algorithm/protocol out of bounds - algo=%s (max %d), proto=%s (max %d)",
+                           algorithmToString(config->algorithm), numAlgo, protocolToString(config->protocol), numProto);
+        }
+      }
+    } else {
+      if (ctx->logFunction) {
+        ctx->logFunction(NCCL_LOG_INFO, NCCL_TUNING, __FILE__, __LINE__,
+                         "TUNER/ExamplePlugin: Config does not match - collType match=%d, size match=%d, nodes match=%d, ranks match=%d, pipeOps match=%d, regBuff match=%d",
+                         config->collType == collType,
+                         (nBytes >= config->minBytes && nBytes <= config->maxBytes),
+                         (config->nNodes == -1 || config->nNodes == (int)ctx->nNodes),
+                         (config->nRanks == -1 || config->nRanks == (int)ctx->nRanks),
+                         (config->numPipeOps == -1 || config->numPipeOps == numPipeOps),
+                         (config->regBuff == -1 || config->regBuff == regBuff));
+      }
+    }
+  }
+
+  // If no specific config found, apply default behavior
+  if (ctx->logFunction) {
+    ctx->logFunction(NCCL_LOG_INFO, NCCL_TUNING, __FILE__, __LINE__,
+                     "TUNER/ExamplePlugin: No matching config found");
+  }
+
   return ncclSuccess;
 }
 
-__hidden ncclResult_t pluginDestroy(void* context) { return ncclSuccess; }
+__hidden ncclResult_t pluginDestroy(void* context) {
+  if (context) {
+    TunerContext* ctx = (TunerContext*)context;
+    if (ctx->configs) {
+      free(ctx->configs);  // Free dynamically allocated configs array
+    }
+    free(context);
+  }
+  return ncclSuccess;
+}
 
 #define PLUGIN_NAME "Example"
 

ext-tuner/example/scripts/README.md

@@ -0,0 +1,106 @@
+# NCCL Tuner Configuration Scripts
+
+This directory contains scripts for optimizing NCCL tuner configurations based on performance data.
+
+## optimize_config.py
+
+A Python script that reads performance data from CSV files and generates optimal NCCL tuner configurations.
+
+### Usage
+
+```bash
+python scripts/optimize_config.py [options] <input_csv_file>
+```
+
+### Options
+
+- `-o, --output FILE`: Output NCCL tuner config file (default: `nccl_tuner.conf`)
+- `-m, --metric METRIC`: Optimization metric (`cost_metric`, `bandwidth_gbps`, `latency_us`)
+- `--no-header`: Don't add header comments to output file
+- `--dry-run`: Print configurations without writing to file
+
+### CSV Input Format
+
+The input CSV file should have the following columns:
+
+```csv
+collective,size_bytes,algorithm,protocol,channels,nodes,ranks,pipeOps,regBuff,cost_metric,bandwidth_gbps,latency_us
+```
+
+**Required columns:**
+- `collective`: NCCL collective type (`allreduce`, `broadcast`, `reduce`, etc.)
+- `size_bytes`: Message size in bytes
+- `algorithm`: NCCL algorithm (`tree`, `ring`, `nvls`, etc.)
+- `protocol`: NCCL protocol (`simple`, `ll`, `ll128`)
+- `channels`: Number of channels (or `-1` for default)
+- `nodes`: Number of nodes (or `-1` for any)
+- `ranks`: Number of ranks (or `-1` for any)
+- `pipeOps`: Number of pipeline operations (or `-1` for any)
+- `regBuff`: Registered buffer flag (`0`, `1`, or `-1` for any)
+
+**Optional metrics (must have at least one present):**
+- `bandwidth_gbps`: Bandwidth in GB/s (higher is better)
+- `latency_us`: Latency in microseconds (lower is better)
+
+### Examples
+
+**Basic usage with cost optimization:**
+```bash
+python scripts/optimize_config.py sample_performance_data.csv
+```
+
+**Optimize for bandwidth and write to custom file:**
+```bash
+python scripts/optimize_config.py -m bandwidth_gbps -o my_tuner.conf performance_data.csv
+```
+
+**Preview configurations without writing:**
+```bash
+python scripts/optimize_config.py --dry-run performance_data.csv
+```
+
+### How It Works
+
+1. **Data Loading**: Reads CSV performance data and validates format
+2. **Grouping**: Groups data by collective type, topology (nodes/ranks), and other parameters
+3. **Size Ranges**: Automatically bins data into size ranges for optimization
+4. **Optimization**: Finds the best performing configuration for each group/size combination
+5. **Output**: Generates NCCL tuner config format and appends to specified file
+
+### Default Size Ranges
+
+The script uses these default size ranges (in bytes):
+- Small: 0 - 1,024
+- Medium: 1,025 - 65,536
+- Large: 65,537 - 1,048,576
+- XLarge: 1,048,577 - 16,777,216
+- XXLarge: 16,777,217 - 4,294,967,295
+
+### Sample Data
+
+See `sample_performance_data.csv` for an example of the expected input format.
+
+### Integration with NCCL
+
+The generated configuration file can be used directly with the NCCL tuner plugin:
+
+```bash
+export NCCL_TUNER_CONFIG_FILE=/path/to/optimized_config.conf
+export NCCL_TUNER_PLUGIN=/path/to/libnccl-tuner.so
+mpirun -np 8 your_nccl_application
+```
+
+### Performance Data Collection
+
+To collect performance data for optimization, you can:
+
+1. **Use NCCL benchmarks** with different algorithm/protocol combinations
+2. **Profile your applications** with various tuner settings
+3. **Run systematic sweeps** across parameter combinations
+4. **Use NCCL debug output** to collect timing information
+
+The key is to have comprehensive data covering:
+- Different message sizes (small to large)
+- Various topologies (single node, multi-node)
+- All relevant algorithm/protocol combinations
+- Different channel counts and pipeline configurations

ext-tuner/example/scripts/optimize_config.py

@@ -0,0 +1,430 @@
+#!/usr/bin/env python3
+"""
+NCCL Tuner Configuration Optimizer
+
+Reads a CSV file containing performance data across different tuning parameters
+and generates optimal NCCL tuner configurations based on the best performing
+combinations.
+
+By default, creates growing size ranges that interpolate between the actual data sizes
+for each unique dimension (node count, rank count combination). This ensures that
+different cluster configurations get their own optimized size boundaries, as
+performance characteristics often vary significantly between topologies.
+
+Each dimension gets its own set of ranges starting from 0 and extending to the maximum
+size for that dimension, with boundaries at midpoints between consecutive data sizes.
+
+CSV Input Format:
+collective,size_bytes,algorithm,protocol,channels,nodes,ranks,pipeOps,regBuff,bandwidth_gbps,latency_us
+
+Output Format (NCCL Tuner Config):
+collective_type,min_bytes,max_bytes,algorithm,protocol,channels,nNodes,nRanks,numPipeOps,regBuff
+
+Usage Examples:
+  # Auto-create dimension-specific interpolated ranges (default)
+  python3 optimize_config.py data.csv
+
+  # Use custom size ranges (applied to all topologies)
+  python3 optimize_config.py data.csv --size-ranges "0-1024,1025-65536,65537-1048576"
+
+  # Use hardcoded default ranges (applied to all topologies)
+  python3 optimize_config.py data.csv --no-auto-ranges
+"""
+
+import csv
+import argparse
+import sys
+import os
+from collections import defaultdict
+from typing import Dict, List, Tuple, Any
+
+class PerformanceData:
+    def __init__(self, row: Dict[str, str]):
+        self.collective = row['collective']
+        self.size_bytes = int(row['size_bytes'])
+        self.algorithm = row['algorithm']
+        self.protocol = row['protocol']
+        self.channels = int(row['channels']) if row['channels'] != '-1' else -1
+        self.nodes = int(row['nodes']) if row['nodes'] != '-1' else -1
+        self.ranks = int(row['ranks']) if row['ranks'] != '-1' else -1
+        self.pipeOps = int(row['pipeOps']) if row['pipeOps'] != '-1' else -1
+        self.regBuff = int(row['regBuff']) if row['regBuff'] != '-1' else -1
+
+        # Performance metrics
+        self.bandwidth_gbps = float(row.get('bandwidth_gbps', 0))  # Higher is better
+        self.latency_us = float(row.get('latency_us', 0))  # Lower is better
+
+    def get_config_key(self) -> Tuple:
+        """Generate a key for grouping similar configurations"""
+        return (self.collective, self.nodes, self.ranks, self.pipeOps, self.regBuff)
+
+    def get_size_range_key(self, topology_size_ranges: Dict[Tuple[int, int], List[Tuple[int, int]]]) -> Tuple[int, int]:
+        """Find which size range this data point belongs to for its dimension"""
+        topology_key = (self.nodes, self.ranks)
+
+        # Get size ranges for this dimension, or fall back to default
+        if topology_key in topology_size_ranges:
+            size_ranges = topology_size_ranges[topology_key]
+        elif (-1, -1) in topology_size_ranges:
+            size_ranges = topology_size_ranges[(-1, -1)]
+        else:
+            # Fallback to first available dimension ranges
+            size_ranges = next(iter(topology_size_ranges.values()))
+
+        for min_size, max_size in size_ranges:
+            if min_size <= self.size_bytes <= max_size:
+                return (min_size, max_size)
+        # If no range found, create a single-point range
+        return (self.size_bytes, self.size_bytes)
+
+class ConfigOptimizer:
+    def __init__(self, optimization_metric: str = 'latency_us'):
+        self.optimization_metric = optimization_metric
+        # Default size ranges - will be overridden by auto-detection
+        self.size_ranges = [
+            (0, 1024),
+            (1025, 64*1024),
+            (64*1024+1, 1024*1024),
+            (1024*1024+1, 16*1024*1024),
+            (16*1024*1024+1, 4*1024*1024*1024-1)
+        ]
+        self.auto_size_ranges = True
+
+    def set_size_ranges(self, ranges: List[Tuple[int, int]]):
+        """Set custom size ranges for optimization"""
+        self.size_ranges = ranges
+        self.auto_size_ranges = False
+
+    def auto_determine_size_ranges(self, data: List[PerformanceData]) -> Dict[Tuple[int, int], List[Tuple[int, int]]]:
+        """Create growing size ranges for each unique (nodes, ranks) dimension"""
+        if not data:
+            return {(-1, -1): self.size_ranges}
+
+        # Group data by dimension (nodes, ranks)
+        topology_data = defaultdict(list)
+        for item in data:
+            topology_key = (item.nodes, item.ranks)
+            topology_data[topology_key].append(item)
+
+        topology_ranges = {}
+
+        for topology_key, items in topology_data.items():
+            nodes, ranks = topology_key
+
+            # Extract unique sizes for this dimension and sort them
+            unique_sizes = sorted(set(item.size_bytes for item in items))
+
+            if len(unique_sizes) <= 1:
+                # Only one size, create a single range from 0 to that size
+                size = unique_sizes[0] if unique_sizes else 0
+                ranges = [(0, size)]
+            else:
+                # Create growing ranges that interpolate between data points
+                ranges = []
+
+                for i, size in enumerate(unique_sizes):
+                    if i == 0:
+                        # First range: 0 to midpoint between first and second size
+                        if len(unique_sizes) > 1:
+                            next_size = unique_sizes[i + 1]
+                            max_size = (size + next_size) // 2
+                        else:
+                            max_size = size
+                        min_size = 0
+                    elif i == len(unique_sizes) - 1:
+                        # Last range: previous max + 1 to current size (and beyond)
+                        min_size = ranges[-1][1] + 1
+                        max_size = size
+                    else:
+                        # Intermediate ranges: previous max + 1 to midpoint with next size
+                        min_size = ranges[-1][1] + 1
+                        next_size = unique_sizes[i + 1]
+                        max_size = (size + next_size) // 2
+
+                    ranges.append((min_size, max_size))
+
+            topology_ranges[topology_key] = ranges
+
+            print(f"Dimension {nodes} nodes, {ranks} ranks: {len(ranges)} size ranges from {len(unique_sizes)} unique sizes:")
+            for i, (min_size, max_size) in enumerate(ranges):
+                # Count data points that fall in this range for this dimension
+                count = sum(1 for item in items if min_size <= item.size_bytes <= max_size)
+                actual_sizes = sorted(set(item.size_bytes for item in items if min_size <= item.size_bytes <= max_size))
+                if actual_sizes:
+                    size_list = ', '.join(f"{s:,}" for s in actual_sizes[:3])
+                    if len(actual_sizes) > 3:
+                        size_list += f", ... (+{len(actual_sizes)-3} more)"
+                    print(f"  Range {i+1}: {min_size:,} - {max_size:,} bytes ({count} data points, sizes: {size_list})")
+
+        return topology_ranges
+
+    def load_data(self, csv_file: str) -> List[PerformanceData]:
+        """Load performance data from CSV file"""
+        data = []
+        try:
+            with open(csv_file, 'r') as f:
+                reader = csv.DictReader(f)
+                for row in reader:
+                    try:
+                        data.append(PerformanceData(row))
+                    except (ValueError, KeyError) as e:
+                        print(f"Warning: Skipping invalid row: {row} - {e}")
+        except FileNotFoundError:
+            print(f"Error: File {csv_file} not found")
+            sys.exit(1)
+        except Exception as e:
+            print(f"Error reading {csv_file}: {e}")
+            sys.exit(1)
+
+        print(f"Loaded {len(data)} performance data points")
+
+        # Auto-determine size ranges if enabled
+        if self.auto_size_ranges and data:
+            self.topology_size_ranges = self.auto_determine_size_ranges(data)
+        else:
+            # Use default ranges for all topologies
+            self.topology_size_ranges = {(-1, -1): self.size_ranges}
+
+        return data
+
+    def is_better(self, new_data: PerformanceData, current_best: PerformanceData) -> bool:
+        """Determine if new_data is better than current_best"""
+        if self.optimization_metric == 'bandwidth_gbps':
+            return new_data.bandwidth_gbps > current_best.bandwidth_gbps
+        elif self.optimization_metric == 'latency_us':
+            return new_data.latency_us < current_best.latency_us
+        else:
+            # Default to latency
+            return new_data.latency_us < current_best.latency_us
+
+    def optimize_configurations(self, data: List[PerformanceData]) -> List[str]:
+        """Find optimal configurations and return as NCCL config strings"""
+        # Group data by configuration key and size range
+        grouped_data = defaultdict(lambda: defaultdict(list))
+
+        for item in data:
+            config_key = item.get_config_key()
+            size_range = item.get_size_range_key(self.topology_size_ranges)
+            grouped_data[config_key][size_range].append(item)
+
+        # Store optimal configurations before combining ranges
+        optimal_configs = []
+
+        for config_key, size_ranges_dict in grouped_data.items():
+            collective, nodes, ranks, pipeOps, regBuff = config_key
+
+            for (min_size, max_size), items in size_ranges_dict.items():
+                if not items:
+                    continue
+
+                # Find the best performing configuration for this size range
+                best_item = items[0]
+                for item in items[1:]:
+                    if self.is_better(item, best_item):
+                        best_item = item
+
+                # Store the optimal configuration with its range
+                optimal_configs.append({
+                    'collective': collective,
+                    'min_size': min_size,
+                    'max_size': max_size,
+                    'algorithm': best_item.algorithm,
+                    'protocol': best_item.protocol,
+                    'channels': best_item.channels,
+                    'nodes': best_item.nodes,
+                    'ranks': best_item.ranks,
+                    'pipeOps': best_item.pipeOps,
+                    'regBuff': best_item.regBuff,
+                    'metric_value': getattr(best_item, self.optimization_metric)
+                })
+
+        # Combine sequential ranges with identical tunings
+        combined_configs = self.combine_sequential_ranges(optimal_configs)
+
+        # Generate config strings
+        configs = []
+        for config in combined_configs:
+            config_str = f"{config['collective']},{config['min_size']},{config['max_size']},{config['algorithm']},{config['protocol']},{config['channels']},{config['nodes']},{config['ranks']},{config['pipeOps']},{config['regBuff']}"
+            configs.append(config_str)
+
+            print(f"Optimal for {config['collective']} [{config['min_size']}-{config['max_size']}] nodes={config['nodes']} ranks={config['ranks']}: "
+                  f"{config['algorithm']}/{config['protocol']} channels={config['channels']} "
+                  f"({self.optimization_metric}={config['metric_value']:.3f})")
+
+        return configs
+
+    def combine_sequential_ranges(self, configs: List[Dict]) -> List[Dict]:
+        """Combine sequential ranges that have identical tuning parameters"""
+        if not configs:
+            return configs
+
+        # Group by collective and topology (nodes, ranks)
+        topology_groups = defaultdict(list)
+        for config in configs:
+            topology_key = (config['collective'], config['nodes'], config['ranks'],
+                          config['pipeOps'], config['regBuff'])
+            topology_groups[topology_key].append(config)
+
+        combined_configs = []
+
+        for topology_key, topology_configs in topology_groups.items():
+            # Sort by min_size to ensure proper ordering
+            topology_configs.sort(key=lambda x: x['min_size'])
+
+            # Group by tuning parameters (algorithm, protocol, channels)
+            tuning_groups = defaultdict(list)
+            for config in topology_configs:
+                tuning_key = (config['algorithm'], config['protocol'], config['channels'])
+                tuning_groups[tuning_key].append(config)
+
+            # For each tuning group, combine sequential ranges
+            for tuning_key, tuning_configs in tuning_groups.items():
+                if not tuning_configs:
+                    continue
+
+                # Sort by min_size
+                tuning_configs.sort(key=lambda x: x['min_size'])
+
+                # Combine sequential ranges
+                current_config = tuning_configs[0].copy()
+
+                for next_config in tuning_configs[1:]:
+                    # Check if ranges are adjacent or overlapping
+                    if current_config['max_size'] + 1 >= next_config['min_size']:
+                        # Extend the current range
+                        current_config['max_size'] = max(current_config['max_size'], next_config['max_size'])
+                        # Update metric value to the better one
+                        if self.optimization_metric == 'bandwidth_gbps':
+                            if next_config['metric_value'] > current_config['metric_value']:
+                                current_config['metric_value'] = next_config['metric_value']
+                        else:  # latency_us or default
+                            if next_config['metric_value'] < current_config['metric_value']:
+                                current_config['metric_value'] = next_config['metric_value']
+                    else:
+                        # Gap between ranges, save current and start new one
+                        combined_configs.append(current_config)
+                        current_config = next_config.copy()
+
+                # Add the last configuration
+                combined_configs.append(current_config)
+
+        # Sort final configs by collective, nodes, ranks, then min_size
+        combined_configs.sort(key=lambda x: (x['collective'], x['nodes'], x['ranks'], x['min_size']))
+
+        original_count = len(configs)
+        combined_count = len(combined_configs)
+        if combined_count < original_count:
+            print(f"Combined {original_count} ranges into {combined_count} ranges "
+                  f"(reduced by {original_count - combined_count})")
+
+        return combined_configs
+
+    def append_to_config_file(self, configs: List[str], config_file: str, add_header: bool = True):
+        """Append optimized configurations to NCCL tuner config file"""
+        try:
+            # Create directory if it doesn't exist
+            config_dir = os.path.dirname(config_file)
+            if config_dir and not os.path.exists(config_dir):
+                os.makedirs(config_dir)
+                print(f"Created directory: {config_dir}")
+
+            # Check if file exists and has content
+            file_exists = os.path.exists(config_file)
+            add_separator = False
+
+            if file_exists:
+                with open(config_file, 'r') as f:
+                    content = f.read().strip()
+                    add_separator = len(content) > 0
+                print(f"Appending to existing file: {config_file}")
+            else:
+                print(f"Creating new file: {config_file}")
+
+            with open(config_file, 'a') as f:
+                if add_separator:
+                    f.write("\n\n")
+
+                if add_header:
+                    f.write(f"# Optimized configurations generated by optimize_config.py\n")
+                    f.write(f"# Optimization metric: {self.optimization_metric}\n")
+                    f.write(f"# Format: collective_type,min_bytes,max_bytes,algorithm,protocol,channels,nNodes,nRanks,numPipeOps,regBuff\n")
+
+                for config in configs:
+                    f.write(f"{config}\n")
+
+            if file_exists:
+                print(f"Appended {len(configs)} optimized configurations to {config_file}")
+            else:
+                print(f"Created {config_file} with {len(configs)} optimized configurations")
+
+        except PermissionError:
+            print(f"Error: Permission denied writing to {config_file}")
+            print("Try running with appropriate permissions or choose a different output location")
+            sys.exit(1)
+        except OSError as e:
+            print(f"Error: Cannot create/write to {config_file}: {e}")
+            print("Check that the path is valid and you have write permissions")
+            sys.exit(1)
+        except Exception as e:
+            print(f"Unexpected error writing to {config_file}: {e}")
+            sys.exit(1)
+
+def main():
+    parser = argparse.ArgumentParser(description="Optimize NCCL tuner configurations from performance data")
+    parser.add_argument("csv_file", help="Input CSV file with performance data")
+    parser.add_argument("-o", "--output", default="nccl_tuner.conf",
+                       help="Output NCCL tuner config file (default: nccl_tuner.conf)")
+    parser.add_argument("-m", "--metric", choices=['bandwidth_gbps', 'latency_us'],
+                       default='latency_us', help="Optimization metric (default: latency_us)")
+    parser.add_argument("--no-header", action="store_true",
+                       help="Don't add header comments to output file")
+    parser.add_argument("--dry-run", action="store_true",
+                       help="Print configurations without writing to file")
+    parser.add_argument("--no-auto-ranges", action="store_true",
+                       help="Disable automatic size range determination (use default ranges)")
+    parser.add_argument("--size-ranges", type=str,
+                       help="Custom size ranges as comma-separated pairs: 'min1-max1,min2-max2,...'")
+
+    args = parser.parse_args()
+
+    optimizer = ConfigOptimizer(args.metric)
+
+    # Handle size range configuration
+    if args.size_ranges:
+        # Parse custom size ranges
+        try:
+            ranges = []
+            for range_str in args.size_ranges.split(','):
+                min_size, max_size = map(int, range_str.split('-'))
+                ranges.append((min_size, max_size))
+            optimizer.set_size_ranges(ranges)
+            print(f"Using custom size ranges: {ranges}")
+        except ValueError:
+            print("Error: Invalid size ranges format. Use 'min1-max1,min2-max2,...'")
+            sys.exit(1)
+    elif args.no_auto_ranges:
+        # Disable auto-ranging
+        optimizer.auto_size_ranges = False
+        print("Using default hardcoded size ranges")
+    else:
+        # Auto-ranging is enabled by default - creates one bucket per unique size
+        optimizer.auto_size_ranges = True
+        print("Auto-ranging enabled: will create one bucket per unique size in data")
+
+    # Load and optimize data
+    data = optimizer.load_data(args.csv_file)
+    if not data:
+        print("No valid data found in CSV file")
+        sys.exit(1)
+
+    configs = optimizer.optimize_configurations(data)
+
+    if args.dry_run:
+        print("\nGenerated configurations:")
+        for config in configs:
+            print(config)
+    else:
+        optimizer.append_to_config_file(configs, args.output, not args.no_header)
+
+if __name__ == "__main__":
+    main()

ext-tuner/example/scripts/sample_performance_data.csv

@@ -0,0 +1,24 @@
+collective,size_bytes,algorithm,protocol,channels,nodes,ranks,pipeOps,regBuff,cost_metric,bandwidth_gbps,latency_us
+allreduce,1024,tree,simple,2,1,8,-1,-1,0.15,45.2,12.5
+allreduce,1024,ring,simple,4,1,8,-1,-1,0.12,52.1,10.8
+allreduce,1024,tree,ll,2,1,8,-1,-1,0.18,41.3,15.2
+allreduce,1024,ring,ll,4,1,8,-1,-1,0.14,48.7,12.1
+allreduce,32768,tree,simple,2,1,8,-1,-1,0.25,156.8,25.3
+allreduce,32768,ring,simple,4,1,8,-1,-1,0.18,189.2,18.4
+allreduce,32768,ring,ll128,8,1,8,-1,-1,0.16,201.5,16.2
+allreduce,1048576,ring,simple,4,1,8,-1,-1,0.45,425.6,45.1
+allreduce,1048576,ring,ll128,8,1,8,-1,-1,0.38,482.3,38.7
+allreduce,1048576,nvls,simple,16,1,8,-1,-1,0.32,551.2,32.1
+broadcast,1024,tree,simple,2,1,8,-1,-1,0.08,89.4,8.2
+broadcast,1024,ring,simple,4,1,8,-1,-1,0.12,71.3,12.1
+broadcast,32768,tree,simple,2,1,8,-1,-1,0.18,234.7,18.5
+broadcast,32768,ring,ll128,4,1,8,-1,-1,0.15,267.8,15.2
+broadcast,1048576,ring,simple,4,1,8,-1,-1,0.35,612.4,35.1
+broadcast,1048576,ring,ll128,8,1,8,-1,-1,0.28,702.1,28.3
+allreduce,1024,tree,simple,2,2,16,-1,-1,0.22,38.1,22.4
+allreduce,1024,ring,simple,4,2,16,-1,-1,0.19,42.7,19.6
+allreduce,32768,ring,simple,4,2,16,-1,-1,0.28,145.2,28.1
+allreduce,32768,ring,ll128,8,2,16,-1,-1,0.24,167.8,24.3
+allreduce,1048576,ring,simple,4,2,16,-1,-1,0.58,387.5,58.2
+allreduce,1048576,ring,ll128,8,2,16,-1,-1,0.48,456.9,48.1
+allreduce,1048576,nvls,simple,16,2,16,-1,-1,0.42,512.6,42.3

ext-tuner/example/test/Makefile

@@ -0,0 +1,30 @@
+#
+# Makefile for NCCL Tuner Plugin Unit Tests
+#
+
+CC := gcc
+CFLAGS := -Wall -Wextra -g -std=c99 -fPIC
+INC := -I. -I../nccl
+TARGET := test_plugin
+SOURCES := test_plugin.c
+
+# Default target
+all: $(TARGET)
+
+# Build the test executable
+$(TARGET): $(SOURCES)
+	$(CC) $(CFLAGS) $(INC) -o $(TARGET) $(SOURCES)
+
+# Run the tests
+test: $(TARGET)
+	./$(TARGET) $(TEST_CASE)
+
+# Run tests with verbose output
+test-verbose: $(TARGET)
+	NCCL_DEBUG=INFO ./$(TARGET) $(TEST_CASE)
+
+# Clean build artifacts
+clean:
+	rm -f $(TARGET) *.o *.gcov *.gcda *.gcno test_*.conf
+
+.PHONY: all test test-verbose clean

ext-tuner/example/test/README.md

@@ -0,0 +1,205 @@
+# NCCL Tuner Plugin Unit Tests
+
+This directory contains comprehensive unit tests for the NCCL tuner plugin. The tests verify all major functionality including configuration parsing, matching logic, and cost table updates.
+
+## Test Structure
+
+```
+test/
+├── test_plugin.c     # Main unit test file
+├── Makefile          # Build system for tests
+└── README.md         # This file
+```
+
+## Building and Running Tests
+
+### Quick Start
+
+```bash
+# Build and run all tests
+make test
+
+# Or step by step
+make           # Build test executable
+./test_plugin  # Run tests
+```
+
+### Advanced Testing
+
+```bash
+# Run with memory leak detection (requires valgrind)
+make test-memory
+
+# Run with verbose logging
+make test-verbose
+
+# Generate code coverage report (requires gcov)
+make coverage
+
+# Create sample test configuration files
+make test-configs
+```
+
+## Test Coverage
+
+The unit tests cover the following functionality:
+
+### 1. **Plugin Initialization (`test_plugin_init`)**
+- Tests successful plugin initialization
+- Verifies context allocation
+- Tests cleanup on destroy
+
+### 2. **Configuration Parsing (`test_config_parsing_valid`, `test_config_parsing_invalid`)**
+- Valid CSV format parsing
+- Comment and empty line handling
+- Invalid format graceful handling
+- Environment variable configuration
+
+### 3. **Collective Type Matching (`test_collective_matching`)**
+- Correct matching of allreduce, broadcast, etc.
+- Algorithm/protocol selection
+- Channel configuration
+
+### 4. **Size Range Matching (`test_size_matching`)**
+- Small, medium, large message size handling
+- Proper range boundary checking
+- Multiple size-based configurations
+
+### 5. **Topology Matching (`test_topology_matching`)**
+- Single-node vs multi-node configurations
+- Exact nNodes/nRanks matching
+- Wildcard matching (-1 values)
+
+### 6. **Default Channels (`test_default_channels`)**
+- Proper handling of -1 channel specification
+- Preservation of NCCL default behavior
+
+### 7. **Registered Buffer Matching (`test_regbuff_matching`)**
+- Configurations based on regBuff parameter
+- Registered vs non-registered buffer handling
+- Backward compatibility with configs missing regBuff
+
+### 8. **Pipeline Operations Matching (`test_pipeops_matching`)**
+- Configurations based on numPipeOps parameter
+- Single vs multiple pipeline operation handling
+- Backward compatibility with configs missing numPipeOps
+
+### 9. **Fallback Behavior (`test_no_match_fallback`)**
+- Default behavior when no config matches
+- Ring/Simple algorithm fallback
+
+## Test Output
+
+Successful test run:
+```
+Running NCCL Tuner Plugin Unit Tests
+=====================================
+PASS: test_plugin_init
+PASS: test_config_parsing_valid
+PASS: test_config_parsing_invalid
+PASS: test_collective_matching
+PASS: test_size_matching
+PASS: test_topology_matching
+PASS: test_default_channels
+PASS: test_regbuff_matching
+PASS: test_pipeops_matching
+PASS: test_no_match_fallback
+
+=====================================
+Test Results: 9/9 tests passed
+All tests PASSED!
+```
+
+Failed test example:
+```
+FAIL: test_collective_matching - Tree/Simple should have low cost
+Test Results: 8/9 tests passed
+Some tests FAILED!
+```
+
+## Mock NCCL Implementation
+
+The tests use the actual NCCL header files from the `../nccl/` directory:
+
+- `tuner.h` - Complete NCCL tuner interface and type definitions
+- `common.h` - Common NCCL types and logging functions
+- `err.h` - NCCL error codes
+
+This allows testing with the real NCCL interface definitions while still being able to run tests without the full NCCL library installation.
+
+## Integration with CI/CD
+
+```bash
+# Install tests for CI/CD pipeline
+make install-test
+
+# Run as part of automated testing
+make test && echo "Tests passed" || echo "Tests failed"
+```
+
+## Memory Testing
+
+The tests can be run with valgrind for memory leak detection:
+
+```bash
+make test-memory
+```
+
+This will detect:
+- Memory leaks
+- Invalid memory access
+- Use of uninitialized memory
+
+## Code Coverage
+
+Generate code coverage reports to ensure comprehensive testing:
+
+```bash
+make coverage
+# Creates test_plugin.c.gcov with line-by-line coverage
+```
+
+## Adding New Tests
+
+To add a new test:
+
+1. Create a new test function in `test_plugin.c`:
+```c
+int test_new_feature() {
+  // Test setup
+  TEST_ASSERT(condition, "description");
+  // Test cleanup
+  TEST_PASS();
+}
+```
+
+2. Add the test to the main function:
+```c
+total++; passed += test_new_feature();
+```
+
+3. Rebuild and run:
+```bash
+make test
+```
+
+## Debugging Tests
+
+For debugging failed tests:
+
+```bash
+# Compile with debug symbols
+make CFLAGS="-g -O0 -DDEBUG"
+
+# Run with gdb
+gdb ./test_plugin
+```
+
+## Cleaning Up
+
+```bash
+# Remove all build artifacts and temporary files
+make clean
+```
+
+This comprehensive test suite ensures the NCCL tuner plugin works correctly across all supported configurations and edge cases.

ext-tuner/example/test/test_plugin.c

@@ -0,0 +1,856 @@
+/*************************************************************************
+ * Unit tests for NCCL Tuner Plugin
+ ************************************************************************/
+
+#define _GNU_SOURCE  // Enable setenv/unsetenv and other GNU extensions
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+#include <unistd.h>
+#include <sys/stat.h>
+#include <stdarg.h>
+
+
+// Include NCCL tuner header (which includes common.h and err.h)
+#include "tuner.h"
+
+// Include plugin source for testing
+#include "../plugin.c"
+
+// Test framework macros
+#define TEST_ASSERT(condition, message) \
+  do { \
+    if (!(condition)) { \
+      printf("FAIL: %s - %s\n", __func__, message); \
+      return 0; \
+    } \
+  } while(0)
+
+#define TEST_PASS() \
+  do { \
+    printf("PASS: %s\n", __func__); \
+    return 1; \
+  } while(0)
+
+// Global test state
+static int test_log_count = 0;
+
+// Mock logger function
+void mock_logger(ncclDebugLogLevel level, unsigned long flags,
+                 const char* file, int line, const char* fmt, ...) {
+  (void)flags; // Suppress unused parameter warning
+  test_log_count++;
+
+  // Check if we should print based on NCCL_DEBUG level
+  const char* debug_level = getenv("NCCL_DEBUG");
+  int should_print = 0;
+
+  if (debug_level) {
+    if (strcmp(debug_level, "TRACE") == 0) {
+      should_print = 1; // Print everything
+    } else if (strcmp(debug_level, "INFO") == 0 && level <= NCCL_LOG_INFO) {
+      should_print = 1; // Print INFO and below
+    } else if (strcmp(debug_level, "WARN") == 0 && level <= NCCL_LOG_WARN) {
+      should_print = 1; // Print WARN and below
+    }
+  }
+
+  if (!should_print) return;
+
+  // Convert log level to string
+  const char* level_str;
+  switch(level) {
+    case NCCL_LOG_NONE: level_str = "NONE"; break;
+    case NCCL_LOG_VERSION: level_str = "VERSION"; break;
+    case NCCL_LOG_WARN: level_str = "WARN"; break;
+    case NCCL_LOG_INFO: level_str = "INFO"; break;
+    case NCCL_LOG_ABORT: level_str = "ABORT"; break;
+    case NCCL_LOG_TRACE: level_str = "TRACE"; break;
+    default: level_str = "UNKNOWN"; break;
+  }
+
+  // Print log header
+  printf("[TUNER:%s:%s:%d] ", level_str, file, line);
+
+  // Print formatted message
+  va_list args;
+  va_start(args, fmt);
+  vprintf(fmt, args);
+  va_end(args);
+
+  printf("\n");
+}
+
+// Helper function to create test config file
+void create_test_config(const char* filename, const char* content) {
+  FILE* f = fopen(filename, "w");
+  if (f) {
+    fprintf(f, "%s", content);
+    fclose(f);
+  }
+}
+
+// Test 1: Plugin initialization
+int test_plugin_init() {
+  void* context = NULL;
+
+  // Test successful initialization
+  ncclResult_t result = pluginInit(8, 2, mock_logger, &context);
+  TEST_ASSERT(result == ncclSuccess, "Plugin init should succeed");
+  TEST_ASSERT(context != NULL, "Context should be allocated");
+
+  // Clean up
+  pluginDestroy(context);
+  TEST_PASS();
+}
+
+// Test 2: Configuration file parsing - valid CSV
+int test_config_parsing_valid() {
+  const char* test_config =
+    "# Test configuration\n"
+    "allreduce,0,65536,tree,simple,2,1,-1,-1,-1\n"
+    "broadcast,0,32768,ring,ll128,4,2,16,-1,-1\n"
+    "# Comment line\n"
+    "\n"  // Empty line
+    "reduce,1024,2048,tree,simple,-1,-1,-1,-1,-1\n";
+
+  create_test_config("test_valid.conf", test_config);
+
+  // Set environment variable to use our test config
+  setenv("NCCL_TUNER_CONFIG_FILE", "test_valid.conf", 1);
+
+  void* context = NULL;
+  ncclResult_t result = pluginInit(16, 2, mock_logger, &context);
+  TEST_ASSERT(result == ncclSuccess, "Plugin init with valid config should succeed");
+
+  // Clean up
+  pluginDestroy(context);
+  unlink("test_valid.conf");
+  unsetenv("NCCL_TUNER_CONFIG_FILE");
+  TEST_PASS();
+}
+
+// Test 3: Configuration file parsing - invalid CSV
+int test_config_parsing_invalid() {
+  const char* test_config =
+    "allreduce,0,65536,tree,simple,2,1  # Missing nRanks and other fields\n"
+    "invalid_collective,0,1024,ring,simple,1,1,1,-1,-1\n"
+    "broadcast,abc,def,ring,simple,1,1,1,-1,-1\n";  // Invalid numbers
+
+  create_test_config("test_invalid.conf", test_config);
+  setenv("NCCL_TUNER_CONFIG_FILE", "test_invalid.conf", 1);
+
+  void* context = NULL;
+  ncclResult_t result = pluginInit(8, 1, mock_logger, &context);
+  // Should still succeed but with no valid configs loaded
+  TEST_ASSERT(result == ncclSuccess, "Plugin init should succeed even with invalid config");
+
+  // Clean up
+  pluginDestroy(context);
+  unlink("test_invalid.conf");
+  unsetenv("NCCL_TUNER_CONFIG_FILE");
+  TEST_PASS();
+}
+
+// Test 4: Collective type matching
+int test_collective_matching() {
+  const char* test_config =
+    "allreduce,0,65536,tree,simple,8,1,-1,-1,-1\n"
+    "broadcast,0,32768,ring,ll128,4,-1,-1,-1,-1\n";
+
+  create_test_config("test_match.conf", test_config);
+  setenv("NCCL_TUNER_CONFIG_FILE", "test_match.conf", 1);
+
+  void* context = NULL;
+  pluginInit(8, 1, mock_logger, &context);
+
+  // Create mock cost table
+  float cost_table[NCCL_NUM_ALGORITHMS][NCCL_NUM_PROTOCOLS];
+  float* cost_table_ptr[NCCL_NUM_ALGORITHMS];
+  for (int i = 0; i < NCCL_NUM_ALGORITHMS; i++) {
+    cost_table_ptr[i] = cost_table[i];
+    for (int j = 0; j < NCCL_NUM_PROTOCOLS; j++) {
+      cost_table[i][j] = 1.0; // Default high cost
+    }
+  }
+
+  int nChannels;
+
+  // Test allreduce matching (should match first config)
+  ncclResult_t result = pluginGetCollInfo(context, ncclFuncAllReduce, 32768, 1,
+                                          cost_table_ptr, NCCL_NUM_ALGORITHMS, NCCL_NUM_PROTOCOLS,
+                                          0, &nChannels);
+
+  TEST_ASSERT(result == ncclSuccess, "GetCollInfo should succeed");
+  mock_logger(NCCL_LOG_INFO, NCCL_ALL, __FILE__, __LINE__,
+              "DEBUG: Checking cost_table[TREE][SIMPLE] (%p) = %.1f (expecting 0.0)",
+              &cost_table[NCCL_ALGO_TREE][NCCL_PROTO_SIMPLE], cost_table[NCCL_ALGO_TREE][NCCL_PROTO_SIMPLE]);
+  TEST_ASSERT(cost_table[NCCL_ALGO_TREE][NCCL_PROTO_SIMPLE] == 0.0, "Tree/Simple should have low cost");
+  TEST_ASSERT(nChannels == 8, "Should set 8 channels");
+
+  // Test broadcast matching (should match second config)
+  for (int i = 0; i < NCCL_NUM_ALGORITHMS; i++) {
+    for (int j = 0; j < NCCL_NUM_PROTOCOLS; j++) {
+      cost_table[i][j] = 1.0; // Reset costs
+    }
+  }
+
+  result = pluginGetCollInfo(context, ncclFuncBroadcast, 16384, 1,
+                            cost_table_ptr, NCCL_NUM_ALGORITHMS, NCCL_NUM_PROTOCOLS,
+                            0, &nChannels);
+  TEST_ASSERT(result == ncclSuccess, "GetCollInfo should succeed");
+  mock_logger(NCCL_LOG_INFO, NCCL_ALL, __FILE__, __LINE__,
+              "DEBUG: Checking cost_table[RING][LL128] (%p) = %.1f (expecting 0.0)",
+              &cost_table[NCCL_ALGO_RING][NCCL_PROTO_LL128], cost_table[NCCL_ALGO_RING][NCCL_PROTO_LL128]);
+  TEST_ASSERT(cost_table[NCCL_ALGO_RING][NCCL_PROTO_LL128] == 0.0, "Ring/LL128 should have low cost");
+  TEST_ASSERT(nChannels == 4, "Should set 4 channels");
+
+  // Clean up
+  pluginDestroy(context);
+  unlink("test_match.conf");
+  unsetenv("NCCL_TUNER_CONFIG_FILE");
+  TEST_PASS();
+}
+
+// Test 5: Size range matching
+int test_size_matching() {
+  const char* test_config =
+    "allreduce,0,1024,tree,simple,2,-1,-1,-1,-1\n"
+    "allreduce,1025,65536,ring,simple,4,-1,-1,-1,-1\n"
+    "allreduce,65537,4294967295,ring,ll128,8,-1,-1,-1,-1\n";
+
+  create_test_config("test_size.conf", test_config);
+  setenv("NCCL_TUNER_CONFIG_FILE", "test_size.conf", 1);
+
+  void* context = NULL;
+  pluginInit(8, 1, mock_logger, &context);
+
+  float cost_table[NCCL_NUM_ALGORITHMS][NCCL_NUM_PROTOCOLS];
+  float* cost_table_ptr[NCCL_NUM_ALGORITHMS];
+  for (int i = 0; i < NCCL_NUM_ALGORITHMS; i++) {
+    cost_table_ptr[i] = cost_table[i];
+    for (int j = 0; j < NCCL_NUM_PROTOCOLS; j++) {
+      cost_table[i][j] = 1.0;
+    }
+  }
+  int nChannels = 1;
+
+  pluginGetCollInfo(context, ncclFuncAllReduce, 512, 1,
+                    cost_table_ptr, NCCL_NUM_ALGORITHMS, NCCL_NUM_PROTOCOLS,
+                    0, &nChannels);
+  mock_logger(NCCL_LOG_INFO, NCCL_ALL, __FILE__, __LINE__,
+              "DEBUG: Small message - checking cost_table[TREE][SIMPLE] (%p) = %.1f (expecting 0.0)",
+              &cost_table[NCCL_ALGO_TREE][NCCL_PROTO_SIMPLE], cost_table[NCCL_ALGO_TREE][NCCL_PROTO_SIMPLE]);
+  TEST_ASSERT(cost_table[NCCL_ALGO_TREE][NCCL_PROTO_SIMPLE] == 0.0, "Small: Tree/Simple should have low cost");
+  TEST_ASSERT(nChannels == 2, "Small: Should set 2 channels");
+
+  // Test medium message (should match second config)
+  for (int i = 0; i < NCCL_NUM_ALGORITHMS; i++) {
+    for (int j = 0; j < NCCL_NUM_PROTOCOLS; j++) {
+      cost_table[i][j] = 1.0;
+    }
+  }
+
+  pluginGetCollInfo(context, ncclFuncAllReduce, 32768, 1,
+                    cost_table_ptr, NCCL_NUM_ALGORITHMS, NCCL_NUM_PROTOCOLS,
+                    0, &nChannels);
+  mock_logger(NCCL_LOG_INFO, NCCL_ALL, __FILE__, __LINE__,
+              "DEBUG: Medium message - checking cost_table[RING][SIMPLE] (%p) = %.1f (expecting 0.0)",
+              &cost_table[NCCL_ALGO_RING][NCCL_PROTO_SIMPLE], cost_table[NCCL_ALGO_RING][NCCL_PROTO_SIMPLE]);
+  TEST_ASSERT(cost_table[NCCL_ALGO_RING][NCCL_PROTO_SIMPLE] == 0.0, "Medium: Ring/Simple should have low cost");
+  TEST_ASSERT(nChannels == 4, "Medium: Should set 4 channels");
+
+  // Test large message (should match third config)
+  for (int i = 0; i < NCCL_NUM_ALGORITHMS; i++) {
+    for (int j = 0; j < NCCL_NUM_PROTOCOLS; j++) {
+      cost_table[i][j] = 1.0;
+    }
+  }
+
+  pluginGetCollInfo(context, ncclFuncAllReduce, 1048576, 1,
+                    cost_table_ptr, NCCL_NUM_ALGORITHMS, NCCL_NUM_PROTOCOLS,
+                    0, &nChannels);
+  mock_logger(NCCL_LOG_INFO, NCCL_ALL, __FILE__, __LINE__,
+              "DEBUG: Large message - checking cost_table[RING][LL128] (%p) = %.1f (expecting 0.0)",
+              &cost_table[NCCL_ALGO_RING][NCCL_PROTO_LL128], cost_table[NCCL_ALGO_RING][NCCL_PROTO_LL128]);
+  TEST_ASSERT(cost_table[NCCL_ALGO_RING][NCCL_PROTO_LL128] == 0.0, "Large: Ring/LL128 should have low cost");
+  TEST_ASSERT(nChannels == 8, "Large: Should set 8 channels");
+
+  // Clean up
+  pluginDestroy(context);
+  unlink("test_size.conf");
+  unsetenv("NCCL_TUNER_CONFIG_FILE");
+  TEST_PASS();
+}
+
+// Test 6: Topology matching
+int test_topology_matching() {
+  const char* test_config =
+    "allreduce,0,65536,tree,simple,2,1,-1,-1,-1\n"      // Single node only
+    "allreduce,0,65536,ring,simple,4,4,32,-1,-1\n"      // 4 nodes, 32 ranks exactly
+    "allreduce,0,65536,ring,ll128,8,-1,-1,-1,-1\n";     // Any topology
+
+  create_test_config("test_topo.conf", test_config);
+  setenv("NCCL_TUNER_CONFIG_FILE", "test_topo.conf", 1);
+
+  // Test with single node setup
+  void* context1 = NULL;
+  pluginInit(8, 1, mock_logger, &context1);  // 8 ranks, 1 node
+
+  float cost_table[NCCL_NUM_ALGORITHMS][NCCL_NUM_PROTOCOLS];
+  float* cost_table_ptr[NCCL_NUM_ALGORITHMS];
+  for (int i = 0; i < NCCL_NUM_ALGORITHMS; i++) {
+    cost_table_ptr[i] = cost_table[i];
+    for (int j = 0; j < NCCL_NUM_PROTOCOLS; j++) {
+      cost_table[i][j] = 1.0;
+    }
+  }
+
+  int nChannels;
+  pluginGetCollInfo(context1, ncclFuncAllReduce, 32768, 1,
+                    cost_table_ptr, NCCL_NUM_ALGORITHMS, NCCL_NUM_PROTOCOLS,
+                    0, &nChannels);
+  TEST_ASSERT(cost_table[NCCL_ALGO_TREE][NCCL_PROTO_SIMPLE] == 0.0, "Single node: Should match tree config");
+  TEST_ASSERT(nChannels == 2, "Single node: Should set 2 channels");
+
+  pluginDestroy(context1);
+
+  // Test with 4 nodes, 32 ranks setup
+  void* context2 = NULL;
+  pluginInit(32, 4, mock_logger, &context2);  // 32 ranks, 4 nodes
+
+  for (int i = 0; i < NCCL_NUM_ALGORITHMS; i++) {
+    for (int j = 0; j < NCCL_NUM_PROTOCOLS; j++) {
+      cost_table[i][j] = 1.0;
+    }
+  }
+
+  pluginGetCollInfo(context2, ncclFuncAllReduce, 32768, 1,
+                    cost_table_ptr, NCCL_NUM_ALGORITHMS, NCCL_NUM_PROTOCOLS,
+                    0, &nChannels);
+  TEST_ASSERT(cost_table[NCCL_ALGO_RING][NCCL_PROTO_SIMPLE] == 0.0, "4-node: Should match ring/simple config");
+  TEST_ASSERT(nChannels == 4, "4-node: Should set 4 channels");
+
+  // Clean up
+  unlink("test_topo.conf");
+  unsetenv("NCCL_TUNER_CONFIG_FILE");
+  TEST_PASS();
+}
+
+// Test 7: Default channels behavior (-1)
+int test_default_channels() {
+  const char* test_config =
+    "allreduce,0,65536,tree,simple,-1,-1,-1,-1,-1\n";  // Use default channels
+
+  create_test_config("test_default.conf", test_config);
+  setenv("NCCL_TUNER_CONFIG_FILE", "test_default.conf", 1);
+
+  void* context = NULL;
+  pluginInit(8, 1, mock_logger, &context);
+
+  float cost_table[NCCL_NUM_ALGORITHMS][NCCL_NUM_PROTOCOLS];
+  float* cost_table_ptr[NCCL_NUM_ALGORITHMS];
+  for (int i = 0; i < NCCL_NUM_ALGORITHMS; i++) {
+    cost_table_ptr[i] = cost_table[i];
+    for (int j = 0; j < NCCL_NUM_PROTOCOLS; j++) {
+      cost_table[i][j] = 1.0;
+    }
+  }
+
+  int nChannels = 99;  // Set to known value
+  pluginGetCollInfo(context, ncclFuncAllReduce, 32768, 1,
+                    cost_table_ptr, NCCL_NUM_ALGORITHMS, NCCL_NUM_PROTOCOLS,
+                    0, &nChannels);
+
+  TEST_ASSERT(cost_table[NCCL_ALGO_TREE][NCCL_PROTO_SIMPLE] == 0.0, "Should apply algorithm/protocol");
+  TEST_ASSERT(nChannels == 1, "Should keep default channels (1) when config has -1");
+
+  // Clean up
+  pluginDestroy(context);
+  unlink("test_default.conf");
+  unsetenv("NCCL_TUNER_CONFIG_FILE");
+  TEST_PASS();
+}
+
+// Test 8: regBuff matching
+int test_regbuff_matching() {
+  const char* test_config =
+    "allreduce,0,65536,tree,simple,2,-1,-1,-1,1\n"      // Registered buffers only
+    "allreduce,0,65536,ring,simple,4,-1,-1,-1,0\n"      // Non-registered buffers only
+    "allreduce,0,65536,ring,ll128,8,-1,-1,-1,-1\n";     // Any buffer type (backward compatible)
+
+  create_test_config("test_regbuff.conf", test_config);
+  setenv("NCCL_TUNER_CONFIG_FILE", "test_regbuff.conf", 1);
+
+  void* context = NULL;
+  pluginInit(8, 1, mock_logger, &context);
+
+  float cost_table[NCCL_NUM_ALGORITHMS][NCCL_NUM_PROTOCOLS];
+  float* cost_table_ptr[NCCL_NUM_ALGORITHMS];
+  for (int i = 0; i < NCCL_NUM_ALGORITHMS; i++) {
+    cost_table_ptr[i] = cost_table[i];
+  }
+
+  int nChannels;
+
+  // Test registered buffer (should match first config)
+  for (int i = 0; i < NCCL_NUM_ALGORITHMS; i++) {
+    for (int j = 0; j < NCCL_NUM_PROTOCOLS; j++) {
+      cost_table[i][j] = 1.0;
+    }
+  }
+
+  pluginGetCollInfo(context, ncclFuncAllReduce, 32768, 1,
+                    cost_table_ptr, NCCL_NUM_ALGORITHMS, NCCL_NUM_PROTOCOLS,
+                    1, &nChannels);  // regBuff = 1 (registered)
+  TEST_ASSERT(cost_table[NCCL_ALGO_TREE][NCCL_PROTO_SIMPLE] == 0.0, "Registered buffer: Tree/Simple should have low cost");
+  TEST_ASSERT(nChannels == 2, "Registered buffer: Should set 2 channels");
+
+  // Test non-registered buffer (should match second config)
+  for (int i = 0; i < NCCL_NUM_ALGORITHMS; i++) {
+    for (int j = 0; j < NCCL_NUM_PROTOCOLS; j++) {
+      cost_table[i][j] = 1.0;
+    }
+  }
+
+  pluginGetCollInfo(context, ncclFuncAllReduce, 32768, 1,
+                    cost_table_ptr, NCCL_NUM_ALGORITHMS, NCCL_NUM_PROTOCOLS,
+                    0, &nChannels);  // regBuff = 0 (non-registered)
+  TEST_ASSERT(cost_table[NCCL_ALGO_RING][NCCL_PROTO_SIMPLE] == 0.0, "Non-registered buffer: Ring/Simple should have low cost");
+  TEST_ASSERT(nChannels == 4, "Non-registered buffer: Should set 4 channels");
+
+  // Test backward compatibility - config without regBuff should match any regBuff value
+  for (int i = 0; i < NCCL_NUM_ALGORITHMS; i++) {
+    for (int j = 0; j < NCCL_NUM_PROTOCOLS; j++) {
+      cost_table[i][j] = 1.0;
+    }
+  }
+
+  // First try with regBuff=2 (unusual value, should match third config)
+  pluginGetCollInfo(context, ncclFuncAllReduce, 32768, 1,
+                    cost_table_ptr, NCCL_NUM_ALGORITHMS, NCCL_NUM_PROTOCOLS,
+                    2, &nChannels);  // regBuff = 2 (only third config should match)
+  TEST_ASSERT(cost_table[NCCL_ALGO_RING][NCCL_PROTO_LL128] == 0.0, "Any regBuff: Ring/LL128 should have low cost");
+  TEST_ASSERT(nChannels == 8, "Any regBuff: Should set 8 channels");
+
+  // Clean up
+  pluginDestroy(context);
+  unlink("test_regbuff.conf");
+  unsetenv("NCCL_TUNER_CONFIG_FILE");
+  TEST_PASS();
+}
+
+// Test 9: numPipeOps matching
+int test_pipeops_matching() {
+  const char* test_config =
+    "allreduce,0,65536,tree,simple,2,-1,-1,1,-1\n"      // Single pipeline op
+    "allreduce,0,65536,ring,simple,4,-1,-1,4,-1\n"      // Multiple pipeline ops
+    "allreduce,0,65536,ring,ll128,8,-1,-1,-1,-1\n";     // Any pipeline ops (backward compatible)
+
+  create_test_config("test_pipeops.conf", test_config);
+  setenv("NCCL_TUNER_CONFIG_FILE", "test_pipeops.conf", 1);
+
+  void* context = NULL;
+  pluginInit(8, 1, mock_logger, &context);
+
+  float cost_table[NCCL_NUM_ALGORITHMS][NCCL_NUM_PROTOCOLS];
+  float* cost_table_ptr[NCCL_NUM_ALGORITHMS];
+  for (int i = 0; i < NCCL_NUM_ALGORITHMS; i++) {
+    cost_table_ptr[i] = cost_table[i];
+  }
+
+  int nChannels;
+
+  // Test single pipeline op (should match first config)
+  for (int i = 0; i < NCCL_NUM_ALGORITHMS; i++) {
+    for (int j = 0; j < NCCL_NUM_PROTOCOLS; j++) {
+      cost_table[i][j] = 1.0;
+    }
+  }
+
+  pluginGetCollInfo(context, ncclFuncAllReduce, 32768, 1,
+                    cost_table_ptr, NCCL_NUM_ALGORITHMS, NCCL_NUM_PROTOCOLS,
+                    0, &nChannels);
+  TEST_ASSERT(cost_table[NCCL_ALGO_TREE][NCCL_PROTO_SIMPLE] == 0.0, "Single pipeOp: Tree/Simple should have low cost");
+  TEST_ASSERT(nChannels == 2, "Single pipeOp: Should set 2 channels");
+
+  // Test multiple pipeline ops (should match second config)
+  for (int i = 0; i < NCCL_NUM_ALGORITHMS; i++) {
+    for (int j = 0; j < NCCL_NUM_PROTOCOLS; j++) {
+      cost_table[i][j] = 1.0;
+    }
+  }
+
+  pluginGetCollInfo(context, ncclFuncAllReduce, 32768, 4,
+                    cost_table_ptr, NCCL_NUM_ALGORITHMS, NCCL_NUM_PROTOCOLS,
+                    0, &nChannels);
+  TEST_ASSERT(cost_table[NCCL_ALGO_RING][NCCL_PROTO_SIMPLE] == 0.0, "Multiple pipeOps: Ring/Simple should have low cost");
+  TEST_ASSERT(nChannels == 4, "Multiple pipeOps: Should set 4 channels");
+
+  // Test different number of pipeline ops (should match third config - backward compatible)
+  for (int i = 0; i < NCCL_NUM_ALGORITHMS; i++) {
+    for (int j = 0; j < NCCL_NUM_PROTOCOLS; j++) {
+      cost_table[i][j] = 1.0;
+    }
+  }
+
+  pluginGetCollInfo(context, ncclFuncAllReduce, 32768, 2,
+                    cost_table_ptr, NCCL_NUM_ALGORITHMS, NCCL_NUM_PROTOCOLS,
+                    0, &nChannels);
+  TEST_ASSERT(cost_table[NCCL_ALGO_RING][NCCL_PROTO_LL128] == 0.0, "Any pipeOps: Ring/LL128 should have low cost");
+  TEST_ASSERT(nChannels == 8, "Any pipeOps: Should set 8 channels");
+
+  // Clean up
+  pluginDestroy(context);
+  unlink("test_pipeops.conf");
+  unsetenv("NCCL_TUNER_CONFIG_FILE");
+  TEST_PASS();
+}
+
+// Test 10: No matching configuration (fallback behavior)
+int test_no_match_fallback() {
+  const char* test_config =
+    "broadcast,0,1024,tree,simple,2,-1,-1,-1,-1\n";  // Only broadcast config
+
+  create_test_config("test_fallback.conf", test_config);
+  setenv("NCCL_TUNER_CONFIG_FILE", "test_fallback.conf", 1);
+
+  void* context = NULL;
+  pluginInit(8, 1, mock_logger, &context);
+
+  float cost_table[NCCL_NUM_ALGORITHMS][NCCL_NUM_PROTOCOLS];
+  float* cost_table_ptr[NCCL_NUM_ALGORITHMS];
+  for (int i = 0; i < NCCL_NUM_ALGORITHMS; i++) {
+    cost_table_ptr[i] = cost_table[i];
+    for (int j = 0; j < NCCL_NUM_PROTOCOLS; j++) {
+      cost_table[i][j] = 1.0;
+    }
+  }
+
+  int nChannels;
+  // Try allreduce (should not match, use fallback)
+  pluginGetCollInfo(context, ncclFuncAllReduce, 32768, 1,
+                    cost_table_ptr, NCCL_NUM_ALGORITHMS, NCCL_NUM_PROTOCOLS,
+                    0, &nChannels);
+
+  mock_logger(NCCL_LOG_INFO, NCCL_ALL, __FILE__, __LINE__,
+              "DEBUG: Fallback test - checking cost_table[RING][SIMPLE] (%p) = %.1f (expecting 0.0)",
+              &cost_table[NCCL_ALGO_RING][NCCL_PROTO_SIMPLE], cost_table[NCCL_ALGO_RING][NCCL_PROTO_SIMPLE]);
+  TEST_ASSERT(cost_table[NCCL_ALGO_RING][NCCL_PROTO_SIMPLE] == 1.0, "Should use pass through unmodified");
+  TEST_ASSERT(nChannels == 1, "Should use default channels");
+
+  // Clean up
+  pluginDestroy(context);
+  unlink("test_fallback.conf");
+  unsetenv("NCCL_TUNER_CONFIG_FILE");
+  TEST_PASS();
+}
+
+// Test 11: Large configuration files (testing dynamic allocation)
+int test_large_config() {
+  const char* large_config_file = "test_large.conf";
+
+  // Create a large configuration file with many entries
+  // This tests the dynamic allocation functionality
+  FILE* f = fopen(large_config_file, "w");
+  TEST_ASSERT(f != NULL, "Should be able to create large config file");
+
+  // Write header comment
+  fprintf(f, "# Large configuration file for testing dynamic allocation\n");
+  fprintf(f, "# This file contains many configurations to test memory allocation\n");
+
+  // Generate a large number of configurations (much more than the old MAX_CONFIGS=100)
+  const int num_configs = 500; // 5x the old static limit
+  const char* collectives[] = {"allreduce", "broadcast", "reduce", "allgather", "reducescatter"};
+  const char* algorithms[] = {"tree", "ring", "collnet_direct", "nvls"};
+  const char* protocols[] = {"simple", "ll", "ll128"};
+
+  for (int i = 0; i < num_configs; i++) {
+    // Vary the configurations to create realistic test data
+    const char* coll = collectives[i % 5];
+    const char* algo = algorithms[i % 4];
+    const char* proto = protocols[i % 3];
+
+    size_t min_bytes = (i * 1024) % 1048576; // Vary from 0 to 1MB
+    size_t max_bytes = min_bytes + 65536;    // 64KB range
+    int channels = (i % 8) + 1;              // 1-8 channels
+    int nodes = (i % 4) == 0 ? -1 : (i % 4); // Mix of -1 and 1-3 nodes
+    int ranks = (i % 8) == 0 ? -1 : (i % 32) + 1; // Mix of -1 and 1-32 ranks
+    int pipeOps = (i % 3) == 0 ? -1 : (i % 4) + 1; // Mix of -1 and 1-4 pipeOps
+    int regBuff = (i % 3) == 0 ? -1 : (i % 2); // Mix of -1, 0, 1
+
+    fprintf(f, "%s,%zu,%zu,%s,%s,%d,%d,%d,%d,%d\n",
+            coll, min_bytes, max_bytes, algo, proto, channels, nodes, ranks, pipeOps, regBuff);
+  }
+
+  fclose(f);
+
+  // Set environment to use our large config file
+  setenv("NCCL_TUNER_CONFIG_FILE", large_config_file, 1);
+
+  // Initialize plugin with large config
+  void* context = NULL;
+  ncclResult_t result = pluginInit(16, 4, mock_logger, &context);
+  TEST_ASSERT(result == ncclSuccess, "Plugin init with large config should succeed");
+  TEST_ASSERT(context != NULL, "Context should be allocated");
+
+  // Verify that configurations were loaded
+  TunerContext* ctx = (TunerContext*)context;
+  TEST_ASSERT(ctx->numConfigs == num_configs, "Should load all configurations from large file");
+  TEST_ASSERT(ctx->maxConfigs == num_configs, "maxConfigs should match allocated size");
+  TEST_ASSERT(ctx->configs != NULL, "Configs array should be dynamically allocated");
+
+  // Test that we can access configurations throughout the array
+  // (This would have failed with the old static MAX_CONFIGS=100 limit)
+  for (int i = 0; i < ctx->numConfigs; i++) {
+    TuningConfig* config = &ctx->configs[i];
+    // Basic sanity checks on the loaded configurations
+    TEST_ASSERT(config->collType >= ncclFuncBroadcast && config->collType <= ncclFuncAllReduce,
+                "Collective type should be valid");
+    TEST_ASSERT(config->maxBytes >= config->minBytes, "maxBytes should be >= minBytes");
+    TEST_ASSERT(config->nChannels > 0, "nChannels should be positive");
+  }
+
+  // Test specific configuration access at various indices
+  // Index 0 (first config)
+  TuningConfig* first_config = &ctx->configs[0];
+  TEST_ASSERT(first_config != NULL, "First config should be accessible");
+
+  // Index in middle
+  TuningConfig* mid_config = &ctx->configs[num_configs / 2];
+  TEST_ASSERT(mid_config != NULL, "Middle config should be accessible");
+
+  // Index near end (this would have crashed with static array of 100)
+  TuningConfig* late_config = &ctx->configs[num_configs - 1];
+  TEST_ASSERT(late_config != NULL, "Last config should be accessible");
+
+  // Test memory allocation size - verify we didn't over-allocate
+  mock_logger(NCCL_LOG_INFO, NCCL_ALL, __FILE__, __LINE__,
+              "Successfully loaded %d configurations (dynamic allocation)", ctx->numConfigs);
+  mock_logger(NCCL_LOG_INFO, NCCL_ALL, __FILE__, __LINE__,
+              "Memory allocated for %d configurations (%zu bytes total)",
+              ctx->maxConfigs, ctx->maxConfigs * sizeof(TuningConfig));
+
+  // Test that the plugin can still find matching configurations from the large set
+  float cost_table[NCCL_NUM_ALGORITHMS][NCCL_NUM_PROTOCOLS];
+  float* cost_table_ptr[NCCL_NUM_ALGORITHMS];
+  for (int i = 0; i < NCCL_NUM_ALGORITHMS; i++) {
+    cost_table_ptr[i] = cost_table[i];
+    for (int j = 0; j < NCCL_NUM_PROTOCOLS; j++) {
+      cost_table[i][j] = 1.0; // Default high cost
+    }
+  }
+
+  int nChannels;
+  // Try to find a matching configuration - should work with large config set
+  result = pluginGetCollInfo(context, ncclFuncAllReduce, 32768, 1,
+                            cost_table_ptr, NCCL_NUM_ALGORITHMS, NCCL_NUM_PROTOCOLS,
+                            0, &nChannels);
+  TEST_ASSERT(result == ncclSuccess, "GetCollInfo should work with large config set");
+
+  // Clean up
+  pluginDestroy(context);
+  unlink(large_config_file);
+  unsetenv("NCCL_TUNER_CONFIG_FILE");
+
+  TEST_PASS();
+}
+
+// Test 12: Very large configuration stress test
+int test_very_large_config_stress() {
+  const char* stress_config_file = "test_stress.conf";
+
+  // Create an even larger configuration file to stress test the implementation
+  FILE* f = fopen(stress_config_file, "w");
+  TEST_ASSERT(f != NULL, "Should be able to create stress test config file");
+
+  fprintf(f, "# Stress test configuration with very large number of entries\n");
+
+  // Generate an extremely large number of configurations
+  const int stress_configs = 2000; // 20x the old static limit
+
+  for (int i = 0; i < stress_configs; i++) {
+    // Create varied but valid configurations
+    fprintf(f, "allreduce,%d,%d,ring,simple,4,-1,-1,-1,-1\n",
+            i * 512, (i * 512) + 1024);
+  }
+
+  fclose(f);
+
+  setenv("NCCL_TUNER_CONFIG_FILE", stress_config_file, 1);
+
+  // Test initialization with stress config
+  void* context = NULL;
+  ncclResult_t result = pluginInit(8, 2, mock_logger, &context);
+  TEST_ASSERT(result == ncclSuccess, "Plugin should handle very large config files");
+
+  TunerContext* ctx = (TunerContext*)context;
+  TEST_ASSERT(ctx->numConfigs == stress_configs, "Should load all stress test configurations");
+  TEST_ASSERT(ctx->configs != NULL, "Stress test configs should be allocated");
+
+  mock_logger(NCCL_LOG_INFO, NCCL_ALL, __FILE__, __LINE__,
+              "Stress test - loaded %d configurations successfully", stress_configs);
+  mock_logger(NCCL_LOG_INFO, NCCL_ALL, __FILE__, __LINE__,
+              "Memory usage: %zu bytes for configuration array",
+              stress_configs * sizeof(TuningConfig));
+
+  // Verify we can access configurations throughout the entire range
+  for (int i = 0; i < stress_configs; i += 100) { // Sample every 100th config
+    TuningConfig* config = &ctx->configs[i];
+    TEST_ASSERT(config->collType == ncclFuncAllReduce, "Config should have correct collective type");
+    TEST_ASSERT(config->minBytes == (size_t)(i * 512), "Config should have correct minBytes");
+  }
+
+  // Clean up
+  pluginDestroy(context);
+  unlink(stress_config_file);
+  unsetenv("NCCL_TUNER_CONFIG_FILE");
+
+  TEST_PASS();
+}
+
+// Test 13: Edge case - empty config file
+int test_empty_config() {
+  const char* empty_config_file = "test_empty.conf";
+
+  // Create empty config file (only comments)
+  create_test_config(empty_config_file,
+    "# Empty configuration file\n"
+    "# No actual configurations\n"
+    "\n"
+    "\n");
+
+  setenv("NCCL_TUNER_CONFIG_FILE", empty_config_file, 1);
+
+  void* context = NULL;
+  ncclResult_t result = pluginInit(8, 2, mock_logger, &context);
+  TEST_ASSERT(result == ncclSuccess, "Plugin should handle empty config files");
+
+  TunerContext* ctx = (TunerContext*)context;
+  TEST_ASSERT(ctx->numConfigs == 0, "Should have zero configurations");
+  TEST_ASSERT(ctx->maxConfigs == 0, "Should have zero max configurations");
+  TEST_ASSERT(ctx->configs == NULL, "Should not allocate memory for empty config");
+
+  // Test that plugin still works with no configurations (fallback behavior)
+  float cost_table[NCCL_NUM_ALGORITHMS][NCCL_NUM_PROTOCOLS];
+  float* cost_table_ptr[NCCL_NUM_ALGORITHMS];
+  for (int i = 0; i < NCCL_NUM_ALGORITHMS; i++) {
+    cost_table_ptr[i] = cost_table[i];
+    for (int j = 0; j < NCCL_NUM_PROTOCOLS; j++) {
+      cost_table[i][j] = 1.0;
+    }
+  }
+
+  int nChannels;
+  result = pluginGetCollInfo(context, ncclFuncAllReduce, 32768, 1,
+                            cost_table_ptr, NCCL_NUM_ALGORITHMS, NCCL_NUM_PROTOCOLS,
+                            0, &nChannels);
+  TEST_ASSERT(result == ncclSuccess, "GetCollInfo should work with empty config");
+
+  // Clean up
+  pluginDestroy(context);
+  unlink(empty_config_file);
+  unsetenv("NCCL_TUNER_CONFIG_FILE");
+
+  TEST_PASS();
+}
+
+// Test runner function pointer type
+typedef int (*TestFunction)(void);
+
+// Test registry
+typedef struct {
+  const char* name;
+  TestFunction func;
+  const char* description;
+} TestCase;
+
+// All available tests
+TestCase test_cases[] = {
+  {"init", test_plugin_init, "Plugin initialization"},
+  {"config-valid", test_config_parsing_valid, "Valid configuration parsing"},
+  {"config-invalid", test_config_parsing_invalid, "Invalid configuration parsing"},
+  {"collective", test_collective_matching, "Collective type matching"},
+  {"size", test_size_matching, "Size range matching"},
+  {"topology", test_topology_matching, "Topology matching"},
+  {"channels", test_default_channels, "Default channels behavior"},
+  {"regbuff", test_regbuff_matching, "Registered buffer matching"},
+  {"pipeops", test_pipeops_matching, "Pipeline operations matching"},
+  {"fallback", test_no_match_fallback, "Fallback behavior"},
+  {"large-config", test_large_config, "Large configuration files (dynamic allocation)"},
+  {"stress-config", test_very_large_config_stress, "Very large configuration stress test"},
+  {"empty-config", test_empty_config, "Empty configuration file handling"},
+  {NULL, NULL, NULL} // End marker
+};
+
+// Show help/usage information
+void show_help(const char* program_name) {
+  printf("Usage: %s [test_name ...]\n\n", program_name);
+  printf("Available tests:\n");
+  for (int i = 0; test_cases[i].name != NULL; i++) {
+    printf("  %-15s - %s\n", test_cases[i].name, test_cases[i].description);
+  }
+  printf("\nExamples:\n");
+  printf("  %s                    # Run all tests\n", program_name);
+  printf("  %s init               # Run only initialization test\n", program_name);
+  printf("  %s init collective    # Run initialization and collective tests\n", program_name);
+  printf("  %s --help             # Show this help\n", program_name);
+}
+
+// Find test by name
+TestFunction find_test(const char* name) {
+  for (int i = 0; test_cases[i].name != NULL; i++) {
+    if (strcmp(test_cases[i].name, name) == 0) {
+      return test_cases[i].func;
+    }
+  }
+  return NULL;
+}
+
+// Main test runner
+int main(int argc, char* argv[]) {
+  int passed = 0, total = 0;
+
+  // Check for help
+  if (argc > 1 && (strcmp(argv[1], "--help") == 0 || strcmp(argv[1], "-h") == 0)) {
+    show_help(argv[0]);
+    return 0;
+  }
+
+  printf("Running NCCL Tuner Plugin Unit Tests\n");
+  printf("=====================================\n");
+
+  if (argc == 1) {
+    // No arguments - run all tests
+    for (int i = 0; test_cases[i].name != NULL; i++) {
+      total++;
+      passed += test_cases[i].func();
+    }
+  } else {
+    // Run specific tests
+    for (int arg = 1; arg < argc; arg++) {
+      TestFunction test_func = find_test(argv[arg]);
+      if (test_func) {
+        total++;
+        passed += test_func();
+      } else {
+        printf("ERROR: Unknown test '%s'\n", argv[arg]);
+        printf("Use --help to see available tests\n");
+        return 1;
+      }
+    }
+  }
+
+  printf("\n=====================================\n");
+  printf("Test Results: %d/%d tests passed\n", passed, total);
+
+  if (passed == total) {
+    printf("All tests PASSED!\n");
+    return 0;
+  } else {
+    printf("Some tests FAILED!\n");
+    return 1;
+  }
+}

makefiles/common.mk

@@ -40,10 +40,12 @@ ifeq ($(shell test "0$(CUDA_MAJOR)" -lt 12; echo $$?),0)
 CUDA8_GENCODE += -gencode=arch=compute_35,code=sm_35
 endif
 CUDA9_GENCODE = -gencode=arch=compute_70,code=sm_70
+CUDA10_GENCODE = -gencode=arch=compute_75,code=sm_75
 CUDA11_GENCODE = -gencode=arch=compute_80,code=sm_80
 CUDA12_GENCODE = -gencode=arch=compute_90,code=sm_90
-CUDA13_GENCODE = -gencode=arch=compute_100,code=sm_100 \
+CUDA12_8_GENCODE = -gencode=arch=compute_100,code=sm_100 \
                    -gencode=arch=compute_120,code=sm_120
+CUDA13_GENCODE = -gencode=arch=compute_110,code=sm_110
 
 CUDA8_PTX     = -gencode=arch=compute_61,code=compute_61
 CUDA9_PTX     = -gencode=arch=compute_70,code=compute_70
@@ -53,10 +55,10 @@ CUDA13_PTX    = -gencode=arch=compute_120,code=compute_120
 
 ifeq ($(shell test "0$(CUDA_MAJOR)" -ge 13; echo $$?),0)
 # Prior to SM75 is deprecated from CUDA13.0 onwards
-  NVCC_GENCODE ?= $(CUDA11_GENCODE) $(CUDA12_GENCODE) $(CUDA13_GENCODE) $(CUDA13_PTX)
+  NVCC_GENCODE ?= $(CUDA10_GENCODE) $(CUDA11_GENCODE) $(CUDA12_GENCODE) $(CUDA12_8_GENCODE) $(CUDA13_GENCODE) $(CUDA13_PTX)
 else ifeq ($(shell test "0$(CUDA_MAJOR)" -eq 12 -a "0$(CUDA_MINOR)" -ge 8; echo $$?),0)
 # Include Blackwell support if we're using CUDA12.8 or above
-  NVCC_GENCODE ?= $(CUDA8_GENCODE) $(CUDA9_GENCODE) $(CUDA11_GENCODE) $(CUDA12_GENCODE) $(CUDA13_GENCODE) $(CUDA13_PTX)
+  NVCC_GENCODE ?= $(CUDA8_GENCODE) $(CUDA9_GENCODE) $(CUDA11_GENCODE) $(CUDA12_GENCODE) $(CUDA12_8_GENCODE) $(CUDA13_PTX)
 else ifeq ($(shell test "0$(CUDA_MAJOR)" -eq 11 -a "0$(CUDA_MINOR)" -ge 8 -o "0$(CUDA_MAJOR)" -gt 11; echo $$?),0)
 # Include Hopper support if we're using CUDA11.8 or above
   NVCC_GENCODE ?= $(CUDA8_GENCODE) $(CUDA9_GENCODE) $(CUDA11_GENCODE) $(CUDA12_GENCODE) $(CUDA12_PTX)

makefiles/version.mk

@@ -1,6 +1,6 @@
 ##### version
 NCCL_MAJOR   := 2
 NCCL_MINOR   := 27
-NCCL_PATCH   := 3
+NCCL_PATCH   := 5
 NCCL_SUFFIX  :=
 PKG_REVISION := 1

src/device/Makefile

@@ -36,9 +36,8 @@ define COMPILE
  $(call COMPILE$(or $3,$(suffix $2)),$1,$2)
 endef
 
-ifeq ($(shell echo "$$((1000*$(CUDA_MAJOR) + 10*$(CUDA_MINOR) >= 12080))"),1)
+ifeq ($(shell echo "$$((1000*$(CUDA_MAJOR) + 10*$(CUDA_MINOR) >= 12090))"),1)
-	NVCC_GENCODE_LDMC_FP8 = -gencode=arch=compute_100a,code=sm_100a \
+	NVCC_GENCODE_LDMC_FP8 = -gencode=arch=compute_100f,code=sm_100f
-                     -gencode=arch=compute_120a,code=sm_120a
 else ifeq ($(shell echo "$$((1000*$(CUDA_MAJOR) + 10*$(CUDA_MINOR) >= 12070))"),1)
   NVCC_GENCODE_LDMC_FP8 = -gencode=arch=compute_100a,code=sm_100a
 else

src/device/reduce_kernel.h

@@ -1009,7 +1009,7 @@ struct Apply_LoadMultimem {
     DEFINE_Apply_LoadMultimem_minmax_v4_and_xparts(__nv_bfloat16, bf16x2, 4)
   #endif
 
-  #if NCCL_CUDA_ARCH_FAMILY_SPECIFIC == 1000 || NCCL_CUDA_ARCH_FAMILY_SPECIFIC == 1010 || NCCL_CUDA_ARCH_SPECIFIC == 1200 || NCCL_CUDA_ARCH_SPECIFIC == 1210
+  #if NCCL_CUDA_ARCH_SPECIFIC == 1000 || NCCL_CUDA_ARCH_SPECIFIC == 1010 || NCCL_CUDA_ARCH_FAMILY_SPECIFIC == 1000 || NCCL_CUDA_ARCH_FAMILY_SPECIFIC == 1010 || NCCL_CUDA_ARCH_SPECIFIC == 1200 || NCCL_CUDA_ARCH_SPECIFIC == 1210
     DEFINE_Apply_LoadMultimem_sum_v4_and_xparts(__nv_fp8_e4m3, e4m3x4, 4)
     DEFINE_Apply_LoadMultimem_minmax_v4_and_xparts(__nv_fp8_e4m3, e4m3x4, 4)
     DEFINE_Apply_LoadMultimem_sum_v4_and_xparts(__nv_fp8_e5m2, e5m2x4, 4)

src/device/symmetric/generate.py

@@ -108,7 +108,7 @@ def required_cuda(k):
       if k.algo in ldmc_algos:
         cudart = 12070
         arch = None
-        specific_sms = [100, 120]
+        specific_sms = ["100a", "101a", "100f", "101f", "120a", "121a"]
   return (cudart, arch, specific_sms)
 
 ################################################################################
@@ -145,7 +145,7 @@ def kernel_conds(k):
   if not specific_sms:
     arch_cond = "__CUDA_ARCH__ >= %d"%arch
   else:
-    arch_cond = " || ".join(["0"] + ["NCCL_CUDA_ARCH_SPECIFIC==%d"%(10*sm) for sm in specific_sms])
+    arch_cond = " || ".join(["0"] + ["NCCL_CUDA_ARCH_%sSPECIFIC==%d"%("FAMILY_" if sm[-1] == "f" else "", 10*int(sm.replace('a', '').replace('f', ''))) for sm in specific_sms])
   return cudart_cond, arch_cond
 
 def instantiate(k):

src/graph/paths.cc

@@ -175,6 +175,13 @@ ncclResult_t ncclGetLocalCpu(struct ncclTopoSystem* system, int gpu, int* retCpu
   return ncclSuccess;
 }
 
+static int mergePathType(int type0, int type1){
+  int max = std::max(type0,type1);
+  int min = std::min(type0,type1);
+  if(max == PATH_PHB && min == PATH_C2C) return PATH_P2C;
+  else return max;
+}
+
 static ncclResult_t addInterStep(struct ncclTopoSystem* system, int tx, int ix, int t1, int i1, int t2, int i2) {
   struct ncclTopoNode* cpuNode = system->nodes[tx].nodes+ix;
   struct ncclTopoNode* srcNode = system->nodes[t1].nodes+i1;
@@ -187,7 +194,7 @@ static ncclResult_t addInterStep(struct ncclTopoSystem* system, int tx, int ix,
 
   // Update path characteristics
   srcNode->paths[t2][i2].count = l;
-  srcNode->paths[t2][i2].type = std::max(srcNode->paths[tx][ix].type, cpuNode->paths[t2][i2].type);
+  srcNode->paths[t2][i2].type = mergePathType(srcNode->paths[tx][ix].type, cpuNode->paths[t2][i2].type);
   if (tx == GPU) srcNode->paths[t2][i2].type = PATH_PXN;
   srcNode->paths[t2][i2].bw = std::min(srcNode->paths[tx][ix].bw, cpuNode->paths[t2][i2].bw);
   return ncclSuccess;
@@ -674,9 +681,9 @@ ncclResult_t ncclTopoComputePaths(struct ncclTopoSystem* system, struct ncclComm
       int c;
       NCCLCHECK(ncclGetLocalCpu(system, g, &c));
       if (c == -1) continue;
-      if (gpuNode->paths[NET][n].type == PATH_PHB && gpuNode->paths[CPU][c].type == PATH_C2C) {
+      if (mergePathType(gpuNode->paths[CPU][c].type, netNode->paths[CPU][c].type) == PATH_P2C) {
-        gpuNode->paths[NET][n].type = PATH_P2C;
+        gpuNode->paths[NET][n].type = std::min(PATH_P2C, gpuNode->paths[NET][n].type);
-        netNode->paths[GPU][g].type = PATH_P2C;
+        netNode->paths[GPU][g].type = std::min(PATH_P2C, netNode->paths[GPU][g].type);
       }
     }
   }
@@ -695,16 +702,15 @@ ncclResult_t ncclTopoComputePaths(struct ncclTopoSystem* system, struct ncclComm
           // PXN = PCI + NVLink.
           struct ncclTopoNode* peerNode = system->nodes[GPU].nodes+localGpuIndex;
           // Only use PXN for NIC n if remote GPU p ...
-          if (/* (1) is either connected to the NIC with PXB*/
+          int pxnType = ncclParamPxnC2c() ? PATH_P2C : PATH_PXB;
-              (peerNode->paths[NET][n].type <= PATH_PXB ||
+          if (/* (1) is connected to the NIC with PxN type*/
-               /* or with P2C and PxN over C2C is enabled */
+              peerNode->paths[NET][n].type <= pxnType &&
-               (ncclParamPxnC2c() && peerNode->paths[NET][n].type == PATH_P2C)) &&
               /* and (2) is connected to us through NVLink */
               peerNode->paths[GPU][g].type <= PATH_NVL &&
               /* and (3) is on the same node as us */
               NCCL_TOPO_ID_SYSTEM_ID(peerNode->id) == NCCL_TOPO_ID_SYSTEM_ID(gpu->id) &&
               /* and (4) has either higher bw to that NIC or avoid going through the CPU*/
-              (peerNode->paths[NET][n].bw > gpu->paths[NET][n].bw || gpu->paths[NET][n].type > PATH_PXB))
+              (peerNode->paths[NET][n].bw > gpu->paths[NET][n].bw || gpu->paths[NET][n].type > pxnType))
             // We can use that GPU as relay to communicate with that NIC.
             // Only enabling it in the GPU->NIC direction for now to favor
             // receiving locally and sending remotely (consistent with net.cc)
@@ -725,6 +731,12 @@ ncclResult_t ncclTopoComputePaths(struct ncclTopoSystem* system, struct ncclComm
       }
     }
   }
+
+  // Pre-compute NET local gpus to accelerate search
+  for (int n=0; n<system->nodes[NET].count; n++) {
+    struct ncclTopoNode* net = system->nodes[NET].nodes+n;
+    NCCLCHECK(ncclTopoGetLocalGpu(system, net->id, &net->net.localGpu));
+  }
   return ncclSuccess;
 }
 

src/graph/search.cc

@@ -437,25 +437,46 @@ ncclResult_t ncclTopoCompareGraphs(struct ncclTopoSystem* system, struct ncclTop
   return ncclSuccess;
 }
 
-// Build a sorted list of the NETs to try.
+// Add the preferred NICs ordered by GPU first
-//
+static ncclResult_t ncclTopoPrefNetsGpuFirst(struct ncclTopoSystem* system, int gpu, int nets[NCCL_TOPO_MAX_NODES], int* netCount) {
-// "gpu" can be set to -1 to build a list suitable for all GPUs (search start) or to a given gpu
+  const int nGpus = (gpu == -1) ? system->nodes[GPU].count : 1;
-//  index when trying to get back to the NIC.
+  int gpuCount = nGpus;
-//
+  int gpuIds[NCCL_TOPO_MAX_NODES] = {gpu};
-// The list is built the following way:
+  int firstNets[NCCL_TOPO_MAX_NODES];
-// 1. Select NETs starting with those close to GPU(s), based on paths[n].type.
+  if (gpu == -1)
-// 2. add other NETs satisfying typeInter but not already in the list.
+    for (int g = 0; g < nGpus; g++) gpuIds[g] = g;
 
-ncclResult_t ncclTopoSelectNets(struct ncclTopoSystem* system, int typeInter, int gpu, int nets[NCCL_TOPO_MAX_NODES], int* netCountRet) {
+  for (int c = 0; c < MAXCHANNELS; c++) {
-  ncclResult_t ret = ncclSuccess;
+    for (int g = 0; g < nGpus; g++) {
-  int netCount = 0;
+      if (gpuIds[g] == -1) continue;
-  int localNetCount;
+      int localNet;
-  int localNets[MAXCHANNELS];
+      int64_t netId;
+      struct ncclTopoNode* gpu = system->nodes[GPU].nodes + gpuIds[g];
+      NCCLCHECK(ncclTopoGetLocalNet(system, gpu->gpu.rank, c, &netId, NULL));
+      NCCLCHECK(ncclTopoIdToIndex(system, NET, netId, &localNet));
+      // store the first net found for each GPU in case of duplicates
+      if(c == 0) firstNets[g] = localNet;
+      // if the NET has already been returned for channel 0, that GPU is done
+      if (c > 0 && firstNets[g] == localNet) {
+        gpuIds[g] = -1;
+        gpuCount--;
+        continue;
+      }
+      // only add it to the list if it doesn't already exist
+      int found = 0;
+      while (found < (*netCount) && nets[found] != localNet) found++;
+      if (found == (*netCount)) nets[(*netCount)++] = localNet;
+    }
+    if (gpuCount == 0) break;
+  }
+  return ncclSuccess;
+}
 
-  // First add the preferred NICs
+// Add the preferred NICs ordered by channels first
+static ncclResult_t ncclTopoPrefNetsChannelFirst(struct ncclTopoSystem* system, int gpu, int nets[NCCL_TOPO_MAX_NODES], int* netCount) {
   for (int g = 0; g < system->nodes[GPU].count; g++) {
     if (gpu != -1 && gpu != g) continue;
-    localNetCount = 0;
+    int localNetCount = 0, localNets[MAXCHANNELS];
     struct ncclTopoNode* gpu = system->nodes[GPU].nodes + g;
     for (int c = 0; c < MAXCHANNELS; c++) {
       int64_t netId;
@@ -468,16 +489,40 @@ ncclResult_t ncclTopoSelectNets(struct ncclTopoSystem* system, int typeInter, in
     for (int i = 0; i < localNetCount; i++) {
       int n = localNets[i];
       int found = 0;
-      while (found<netCount && nets[found] != n) found++;
+      while (found < (*netCount) && nets[found] != n) found++;
-      if (found == netCount) nets[netCount++] = n;
+      if (found == (*netCount)) nets[(*netCount)++] = n;
     }
   }
+  return ncclSuccess;
+}
+
+// Build a sorted list of the NETs to try.
+//
+// "gpu" can be set to -1 to build a list suitable for all GPUs (search start) or to a given gpu
+//  index when trying to get back to the NIC.
+//
+// The list is built the following way:
+// 1. Select NETs starting with those close to GPU(s), based on paths[n].type.
+// 2. add other NETs satisfying typeInter but not already in the list.
+NCCL_PARAM(ScatterEnable, "MNNVL_SCATTER_NETS_ENABLE", 1);
+ncclResult_t ncclTopoSelectNets(struct ncclTopoSystem* system, int typeInter, int gpu, int nets[NCCL_TOPO_MAX_NODES], int* netCountRet) {
+  ncclResult_t ret = ncclSuccess;
+  int netCount = 0;
+
+  // First add the preferred NETs.
+  if (system->nHosts > 1 && ncclParamScatterEnable()) {
+    // For MNNVL systems, we sort the devices by GPU first, then by channel
+    NCCLCHECK(ncclTopoPrefNetsGpuFirst(system, gpu, nets, &netCount));
+  } else {
+    // For other systems, we sort the devices by channel first, then by GPU
+    NCCLCHECK(ncclTopoPrefNetsChannelFirst(system, gpu, nets, &netCount));
+  }
 
   // Then add others satisfying typeInter
   for (int t=0; t <= typeInter; t++) {
     for (int g = 0; g < system->nodes[GPU].count; g++) {
       if (gpu != -1 && gpu != g) continue;
-      localNetCount = 0;
+      int localNetCount = 0, localNets[MAXCHANNELS];
       struct ncclTopoNode* gpu = system->nodes[GPU].nodes+g;
       struct ncclTopoLinkList* paths = gpu->paths[NET];
       for (int n=0; n<system->nodes[NET].count && n<MAXCHANNELS; n++) {
@@ -625,8 +670,7 @@ ncclResult_t ncclTopoSearchRecNet(struct ncclTopoSystem* system, struct ncclTopo
     if (graph->pattern == NCCL_TOPO_PATTERN_NVLS || graph->pattern == NCCL_TOPO_PATTERN_COLLNET_DIRECT) {
       // NVLS search only tries to find NIC:GPU combinations to compute the heads.
       if (graph->nChannels < netCount) {
-        int gpu;
+        int gpu = net->net.localGpu;
-        NCCLCHECK(ncclTopoGetLocalGpu(system, net->id, &gpu));
         if (gpu != -1) {
           int duplicate = 0;
           // check whether there is duplicate head when one GPU connects with multiple NICs
@@ -643,13 +687,12 @@ ncclResult_t ncclTopoSearchRecNet(struct ncclTopoSystem* system, struct ncclTopo
         }
       }
     } else {
-      if (graph->nChannels > 0) {
+      if (graph->nChannels > 0 && graph->sameChannels == 1) {
         // Try to replay the last channel
         int g;
         NCCLCHECK(ncclTopoReplayGetGpu(system, graph, -1, &g));
         NCCLCHECK(ncclTopoSearchTryGpu(system, graph, saveGraph, 0, backToNet, backToFirstRank, FORCED_ORDER_REPLAY, time, NET, n, g));
-      }
+      } else {
-      if (graph->nChannels == 0 || graph->sameChannels == 0) {
         if (graph->nChannels == 0 && system->nodes[NVS].count == 0) {
           // Always try the PCI order first to set a reference, but don't count in the timeout nor let it run for long
           int t = 1 << 10;
@@ -658,11 +701,16 @@ ncclResult_t ncclTopoSearchRecNet(struct ncclTopoSystem* system, struct ncclTopo
         }
 
         // Then try the most local GPUs
+        int localGpu = net->net.localGpu;
+        if (localGpu != -1) {
+          NCCLCHECK(ncclTopoSearchTryGpu(system, graph, saveGraph, 0, backToNet, backToFirstRank, 0, time, NET, n, localGpu));
+        }
         int localGpus[NCCL_TOPO_MAX_NODES], localGpuCount, pathType;
         NCCLCHECK(ncclTopoGetLocal(system, NET, n, GPU, localGpus, &localGpuCount, &pathType));
         // if no GPUs are connected, skip this net
         if (pathType == PATH_DIS) continue;
         for (int g = 0; g < localGpuCount; ++g) {
+          if (localGpus[g] == localGpu) continue; // We already tried this one
           NCCLCHECK(ncclTopoSearchTryGpu(system, graph, saveGraph, 0, backToNet, backToFirstRank, 0, time, NET, n, localGpus[g]));
         }
       }
@@ -749,8 +797,8 @@ struct kvDict kvDictLinkType[] = {
   { "NVB", PATH_NVB },
   { "PIX", PATH_PIX },
   { "PXB", PATH_PXB },
-  { "PXN", PATH_PXN },
   { "P2C", PATH_P2C },
+  { "PXN", PATH_PXN },
   { "PHB", PATH_PHB },
   { "SYS", PATH_SYS },
   { NULL, 0 }
@@ -798,8 +846,10 @@ ncclResult_t ncclTopoGetGraphFromXmlSub(struct ncclXmlNode *xmlGraph, struct ncc
   NCCLCHECK(xmlGetAttrInt(xmlGraph, "nchannels", &graph->nChannels));
   NCCLCHECK(xmlGetAttrFloat(xmlGraph, "speedintra", &graph->bwIntra));
   NCCLCHECK(xmlGetAttrFloat(xmlGraph, "speedinter", &graph->bwInter));
-  if (xmlGetAttrFloat(xmlGraph, "latencyinter", &graph->latencyInter) != ncclSuccess) graph->latencyInter = 0.0;
   const char* str;
+  NCCLCHECK(xmlGetAttr(xmlGraph, "latencyinter", &str));
+  if (!str) INFO(NCCL_GRAPH, "latencyinter not found in graph, using 0.0");
+  graph->latencyInter = str ? strtof(str, NULL) : 0.0;
   NCCLCHECK(xmlGetAttr(xmlGraph, "typeintra", &str));
   NCCLCHECK(kvConvertToInt(str, &graph->typeIntra, kvDictLinkType));
   NCCLCHECK(xmlGetAttr(xmlGraph, "typeinter", &str));
@@ -910,7 +960,7 @@ float sm90SpeedArrayInter[] = { 48.0, 45.0, 42.0, 40.0, 30.0, 24.0, 22.0, 20.0,
 #define NSPEEDSINTER_SM90 (sizeof(sm90SpeedArrayInter)/sizeof(float))
 
 float sm100SpeedArrayIntra[] = { 90.0, 80.0, 70.0, 60.0, 50.0, 40.0, 30.0, 24.0, 20.0, 19.0, 18.0 };
-float sm100SpeedArrayInter[] = { 47.9, 45.0, 42.0, 40.0, 30.0, 24.0, 22.0, 20.0, 17.5, 15.0, 12.0, 6.0, 3.0, 2.4, 1.2, 0.24, 0.12 };
+float sm100SpeedArrayInter[] = { 48.0, 45.1, 42.0, 40.0, 30.0, 24.0, 22.0, 20.0, 17.5, 15.0, 12.0, 6.0, 3.0, 2.4, 1.2, 0.24, 0.12 };
 #define NSPEEDSINTRA_SM100 (sizeof(sm100SpeedArrayIntra)/sizeof(float))
 #define NSPEEDSINTER_SM100 (sizeof(sm100SpeedArrayInter)/sizeof(float))
 
@@ -1136,8 +1186,12 @@ ncclResult_t ncclTopoPrintGraph(struct ncclTopoSystem* system, struct ncclTopoGr
       offset = strlen(line);
     }
     for (int i=0; i<ngpus; i++) {
-      sprintf(line+offset, " %s/%d", topoNodeTypeStr[GPU], graph->intra[ngpus*c+i]);
+      int g;
+      ncclTopoRankToIndex(system, graph->intra[ngpus * c + i], &g, true);
+      int64_t topoId = system->nodes[GPU].nodes[g].id;
+      sprintf(line + offset, " %s/%lx-%lx", topoNodeTypeStr[GPU], NCCL_TOPO_ID_SYSTEM_ID(topoId), NCCL_TOPO_ID_LOCAL_ID(topoId));
       offset = strlen(line);
+      if (graph->id == 3) break; // NVLS graphs only use the first GPU
     }
     if (system->nodes[NET].count > 0) {
       sprintf(line+offset, " %s/%lx-%lx", topoNodeTypeStr[NET], NCCL_TOPO_ID_SYSTEM_ID(graph->inter[2*c+1]), NCCL_TOPO_ID_LOCAL_ID(graph->inter[2*c+1]));

src/graph/topo.cc

@@ -21,7 +21,7 @@
 
 const char* topoNodeTypeStr[] = { "GPU", "PCI", "NVS", "CPU", "NIC", "NET" };
 const char* topoLinkTypeStr[] = { "LOC", "NVL", "",    "C2C", "PCI",    "",    "",    "",    "", "SYS", "NET" };
-const char* topoPathTypeStr[] = { "LOC", "NVL", "NVB", "C2C", "PIX", "PXB", "PXN", "P2C", "PHB", "SYS", "NET", "DIS" };
+const char* topoPathTypeStr[] = { "LOC", "NVL", "NVB", "C2C", "PIX", "PXB", "P2C", "PXN", "PHB", "SYS", "NET", "DIS" };
 
 /******************************************************************/
 /******************* Graph Creation Functions *********************/
@@ -677,7 +677,14 @@ ncclResult_t ncclTopoGetSystemFromXml(struct ncclXml* xml, struct ncclTopoSystem
     struct ncclXmlNode* node = topNode->subs[s];
     if (strcmp(node->name, "cpu") == 0) NCCLCHECK(ncclTopoAddCpu(node, *topoSystem));
   }
-  for (int systemId=0; systemId<system->nHosts; systemId++) if (system->hostHashes[systemId] == localHostHash) system->systemId = systemId;
+
+  int systemId = 0;
+  while (systemId < system->nHosts && system->hostHashes[systemId] != localHostHash) systemId++;
+  system->systemId = systemId;
+  if(systemId == system->nHosts){
+    WARN("localHostHash = 0x%lx not found in the list of system hostHashes",localHostHash);
+    return ncclInvalidArgument;
+  }
 
   NCCLCHECK(ncclTopoAddNvLinks(topNode, *topoSystem, NULL, 0));
   NCCLCHECK(ncclTopoAddC2c(topNode, *topoSystem, NULL, 0));
@@ -1143,8 +1150,8 @@ struct kvDict nicPathKvList[] = {
   { "PORT", PATH_PORT },
   { "PIX",  PATH_PIX },
   { "PXB",  PATH_PXB },
-  { "PXN",  PATH_PXN },
   { "P2C",  PATH_P2C },
+  { "PXN",  PATH_PXN },
   { "PHB",  PATH_PHB },
   { "SYS",  PATH_SYS },
   { NULL, 0 }
@@ -1421,7 +1428,7 @@ ncclResult_t ncclTopoGetSystem(struct ncclComm* comm, struct ncclTopoSystem** sy
   }
 
   // Only update our topo tracking structure if we aren't dumping (separate steps)
-  if (dumpXmlFile == NULL) NCCLCHECKGOTO(ncclTopoGetSystemFromXml(xml, system, comm->peerInfo[comm->rank].hostHash), ret, fail);
+  if (dumpXmlFile == NULL) NCCLCHECKGOTO(ncclTopoGetSystemFromXml(xml, system, getHostHash()), ret, fail);
 
 exit:
   if (!comm->MNNVL && localRanks) free(localRanks);

src/graph/topo.h

@@ -18,7 +18,7 @@
 #define SM80_NVLINK_BW 20.0
 #define SM90_NVLINK_BW 20.6
 #define SM86_NVLINK_BW 12.0
-#define SM100_NVLINK_BW 40.0
+#define SM100_NVLINK_BW 40.1
 #define PCI_BW 12.0           // PCI Gen3 x16
 #define AMD_BW 16.0
 #define BDW_QPI_BW 6.0
@@ -76,11 +76,11 @@ extern const char* topoLinkTypeStr[];
 // Connection traversing multiple PCIe bridges (without traversing the PCIe Host Bridge)
 #define PATH_PXB 5
 
-// Connection between a GPU and a NIC using an intermediate GPU. Used to enable rail-local, aggregated network send/recv operations.
-#define PATH_PXN 6
-
 // Connection between a GPU and a NIC using the C2C connection to the CPU and the PCIe connection to the NIC
-#define PATH_P2C 7
+#define PATH_P2C 6
+
+// Connection between a GPU and a NIC using an intermediate GPU. Used to enable rail-local, aggregated network send/recv operations.
+#define PATH_PXN 7
 
 // Connection traversing PCIe as well as a PCIe Host Bridge (typically the CPU)
 #define PATH_PHB 8
@@ -143,6 +143,7 @@ struct ncclTopoNode {
       int gdrSupport;
       int collSupport;
       int maxChannels;
+      int localGpu;
     }net;
     struct {
       int arch;

src/graph/tuning.cc

@@ -455,9 +455,16 @@ ncclResult_t ncclTopoTuneModel(struct ncclComm* comm, int minCompCap, int maxCom
   for (int c=0; c<NCCL_NUM_FUNCTIONS; c++) for (int a=0; a<NCCL_NUM_ALGORITHMS; a++) for (int p=0; p<NCCL_NUM_PROTOCOLS; p++) {
     int pEnable = protoEnable[c*NCCL_NUM_PROTOCOLS+p];
     if (pEnable == 2 && p == NCCL_PROTO_LL128) {
-      // Enable LL128 by default only on Volta/Ampere/Hopper/Blackwell+NVLink. Other cases are not tested and may cause silent data corruption.
       pEnable = 1;
-      pEnable &= (graphs[a]->typeInter <= PATH_PXB || (minCompCap >= 90 && graphs[a]->typeInter <= (ncclParamLl128C2c() ? PATH_P2C : PATH_PXN)));
+      if (ncclParamLl128C2c() && minCompCap >= 90) {
+        // Enable LL128 by default only on Hopper/Blackwell for all connections up to P2C and PXN.
+        pEnable &= (graphs[a]->typeInter <= PATH_PXN);
+      } else {
+        // Enable LL128 only up to PXB. Don't enable LL128 over PxN because PxN can encapsulate PxB or P2C links.
+        pEnable &= (graphs[a]->typeInter <= PATH_PXB);
+        if (!ncclParamLl128C2c() && minCompCap >= 90)
+          INFO(NCCL_GRAPH, "Disabling LL128 over all PxN connections (PXB and C2C). This ensures that no C2C link will be used by LL128.");
+      }
       pEnable &= (graphs[a]->typeIntra <= PATH_NVB);
       pEnable &= (minCompCap == maxCompCap);
       pEnable &= !(minCompCap < 70 || (minCompCap == 90 && CUDART_VERSION == 11080 && c == ncclFuncAllReduce && a == NCCL_ALGO_RING && comm->nRanks == 2));

src/init.cc

@@ -1507,7 +1507,7 @@ static ncclResult_t envConfigOverride(ncclComm_t comm) {
   int minCTAsEnv;
   int maxCTAsEnv;
   int splitShareEnv;
-  int collnetEnableEnv;
+  const char* collnetEnableEnv;
   int ctaPolicyEnv;
   int shrinkShareEnv;
   int nvlsCTAsEnv;
@@ -1561,9 +1561,15 @@ static ncclResult_t envConfigOverride(ncclComm_t comm) {
     comm->config.shrinkShare = shrinkShareEnv;
   }
 
-  collnetEnableEnv = ncclParamCollnetEnable();
+  // NCCL_COLLNET_ENABLE needs to be reloaded each time for comm init
-  if (collnetEnableEnv != NCCL_CONFIG_UNDEF_INT) {
+  // since users might change the env on the fly to enable/disable collnet
-    comm->config.collnetEnable = collnetEnableEnv;
+  collnetEnableEnv = ncclGetEnv("NCCL_COLLNET_ENABLE");
+  if (collnetEnableEnv != NULL) {
+    int collnetEnableInt = (int)strtol(collnetEnableEnv, NULL, 0);
+    if (collnetEnableInt != NCCL_CONFIG_UNDEF_INT) {
+      comm->config.collnetEnable = collnetEnableInt;
+      INFO(NCCL_ENV, "NCCL_COLLNET_ENABLE set by environment to %d.", collnetEnableInt);
+    }
   }
 
   ctaPolicyEnv = ncclParamCtaPolicy();

src/misc/mlx5dvsymbols.cc

@@ -52,6 +52,9 @@ ncclResult_t buildMlx5dvSymbols(struct ncclMlx5dvSymbols* mlx5dvSymbols) {
 #define LOAD_SYM_VERSION(handle, symbol, funcptr, version) do {  \
     cast = (void**)&funcptr;                                     \
     *cast = dlvsym(handle, symbol, version);                     \
+    if (*cast == NULL) {                                         \
+      INFO(NCCL_NET, "dlvsym failed on %s - %s version %s", symbol, dlerror(), version);  \
+    }                                                            \
   } while (0)
 
   LOAD_SYM(mlx5dvhandle, "mlx5dv_is_supported", mlx5dvSymbols->mlx5dv_internal_is_supported);

src/misc/strongstream.cc

@@ -21,7 +21,6 @@ struct ncclStrongStreamCapture {
   cudaGraph_t graph;
   unsigned long long graphId;
   cudaStream_t captureStream;
-  cudaGraphNode_t lastRecord;
   void* acquiredBy;
 };
 
@@ -216,7 +215,6 @@ ncclResult_t ncclStrongStreamAcquire(
         CUDACHECKGOTO(cudaStreamCreateWithFlags(&cap->captureStream, cudaStreamNonBlocking), ret, do_unlock);
       }
       cap->graphId = graph.graphId;
-      cap->lastRecord = nullptr;
       cap->acquiredBy = localThreadId();
       // Push to capturing list.
       cap->next = ss->captureHead;
@@ -296,16 +294,6 @@ ncclResult_t ncclStrongStreamRelease(
         cudaGraphNode_t recordNode;
         CUDACHECK(cudaGraphAddEventRecordNode(&recordNode, graph.graph, nullptr, 0, ss->serialEvent));
 
-        // Make this record order after previous record on this stream.
-        if (cap->lastRecord != nullptr) {
-        #if CUDART_VERSION >= 13000
-          CUDACHECK(cudaGraphAddDependencies_v2(graph.graph, &cap->lastRecord, &recordNode, nullptr, 1));
-        #else
-          CUDACHECK(cudaGraphAddDependencies(graph.graph, &cap->lastRecord, &recordNode, 1));
-        #endif
-        }
-        cap->lastRecord = recordNode;
-
         // Get current nodes from work stream so we can add them as dependencies.
         cudaStreamCaptureStatus status;
         cudaGraphNode_t const* nodes;
@@ -338,6 +326,22 @@ ncclResult_t ncclStrongStreamRelease(
           }
         }
 
+	// Make every future operation captured on cap->captureStream depend on 'recordNode'.
+        #if CUDART_VERSION >= 13000
+        CUDACHECK(cudaStreamUpdateCaptureDependencies_v2(
+                    cap->captureStream,
+                    &recordNode,          /* dependencies                */
+                    /*edges =*/ nullptr,  /* no edge annotations         */
+                    1,                    /* count                       */
+                    cudaStreamSetCaptureDependencies));
+        #else
+        CUDACHECK(cudaStreamUpdateCaptureDependencies(
+                    cap->captureStream,
+                    &recordNode,
+                    1,
+                    cudaStreamSetCaptureDependencies));
+        #endif
+
         if (cap->acquiredBy != localThreadId() && ncclParamLaunchRaceFatal()) {
           WARN("%s", launchRaceFatalMsg);
           return ncclInvalidUsage;

src/plugin/plugin_open.cc

@@ -61,8 +61,6 @@ static void* openPluginLib(enum ncclPluginType type, const char* libName) {
   char eNoEntNameList[PATH_MAX] = { 0 };
 
   if (libName && strlen(libName)) {
-    // match names that start with 'lib' and end with '.so'
-    if (strlen(libName) >= strlen("libX.so") && strncmp(libName, "lib", strlen("lib")) == 0 && strncmp(libName + strlen(libName) - strlen(".so"), ".so", strlen(".so")) == 0) {
     snprintf(libName_, MAX_STR_LEN, "%s", libName);
     libHandles[type] = tryOpenLib(libName_, &openErr, openErrStr);
     if (libHandles[type]) {
@@ -74,7 +72,9 @@ static void* openPluginLib(enum ncclPluginType type, const char* libName) {
     } else {
       INFO(subsys[type], "%s/Plugin: %s", pluginNames[type], openErrStr);
     }
-    } else {
+
+    // libName can't be a relative or absolute path (start with '.' or contain any '/'). It can't be a library name either (start with 'lib' or end with '.so')
+    if (strchr(libName, '/') == nullptr && (strncmp(libName, "lib", strlen("lib")) || strlen(libName) < strlen(".so") || strncmp(libName + strlen(libName) - strlen(".so"), ".so", strlen(".so")))) {
       snprintf(libName_, MAX_STR_LEN, "%s-%s.so", pluginPrefix[type], libName);
       libHandles[type] = tryOpenLib(libName_, &openErr, openErrStr);
       if (libHandles[type]) {

src/transport/net_ib.cc

@@ -494,7 +494,9 @@ static int ibvSpeeds[] = {
   14000, /* FDR */
   25000, /* EDR */
   50000, /* HDR */
-  100000 /* NDR */ };
+  100000, /* NDR */
+  200000  /* XDR */
+};
 
 static int firstBitSet(int val, int max) {
   int i = 0;
@@ -654,7 +656,7 @@ ncclResult_t ncclIbInit(ncclDebugLogger_t logFunction, ncclProfilerCallback_t pr
           ibProvider = IB_PROVIDER_MLX5;
           snprintf(dataDirectDevicePath, PATH_MAX, "/sys");
           if((ncclMlx5dvDmaBufCapable(context)) && (wrap_mlx5dv_get_data_direct_sysfs_path(context, dataDirectDevicePath + 4, PATH_MAX - 4) == ncclSuccess)) {
-            INFO(NCCL_NET, "Data Direct DMA Interface is detected for device:%s", devices[d]->name);
+            INFO(NCCL_INIT|NCCL_NET, "Data Direct DMA Interface is detected for device:%s", devices[d]->name);
             if(ncclParamIbDataDirect()) dataDirectSupported = 1;
           }
         }