NCCL 2.26.2-1

Profiler improvements
 * Add events for CUDA kernel start and end.
 * Allow network plugins to generate profiling events
 * Enable profiling on a per-operation basis, rather than per-communicator.
 * Add support for graph capturing.

Add implicit launch order
 * Allow to prevent deadlocks when using multiple NCCL communicators per
   device by implicitly ordering NCCL operations using the host program
   order. Disabled by default, set NCCL_LAUNCH_ORDER_IMPLICIT=1 to enable.
 * Add a complementary mechanism to detect host threads racing to launch
   to the same device. Enabled by default, set NCCL_LAUNCH_RACE_FATAL=0 to
   disable.

Optimize the PAT algorithm
 * Separate the computation and execution of PAT steps on different warps,
   allowing to run up to 16 PAT steps in parallel to significantly
   accelerate PAT and reduce its linear part.

Add support for setting QoS per communicator
 * Add a new trafficClass field to the communicator configuration, to
   allow the application to select a particular traffic class for a
   given communicator. The meaning of the traffic class is
   network-specific and should be set in accordance with the network
   configuration.
 * For the IB/RoCE plugin, existing config variables such as NCCL_IB_SL
   and NCCL_IB_TC take precedence.

Allow to enable GPU Direct RDMA specifically on C2C platforms
 * Disabled by default, set NCCL_NET_GDR_C2C=1 to enable.

Do not disable user buffer registration unless PXN is really used
 * Only disable UB when a communicator has more than one rank per
   node on any node.

RAS subsystem improvements
 * Report operation counts separately for each collective operation type.
 * Provide details about missing communicator ranks and reliably
   distinguish ranks that are no longer a given communicator's members
   (now reported as NOCOMM) from those that failed to respond.

Add support for timestamps to NCCL diagnostic messages
 * On by default for WARN messages; NCCL_DEBUG_TIMESTAMP_LEVELS can be
   used to enable them for other debug levels as well.
 * The format can be changed using the NCCL_DEBUG_TIMESTAMP_FORMAT config
   variable.

Reduce the memory usage with NVLink SHARP (NVLS)
 * Potentially save hundreds of MBs of device memory, considering the
   multicast buffer size granularity separately from the address alignment.

Update performance tuning for recent Intel CPUs
 * Improve algorithm/protocol selection on recent CPUs such as Emerald
   Rapids and Sapphire Rapids.

Improve channel scheduling when mixing LL and Simple operations.
 * Make LL operations account for 4x more traffic to ensure LL and simple
   operations complete at the same time.

Refactor the plugin code
 * Clean up and harmonize the support code across the network, tuner,
   and profiler plugins.

Add support for comment lines (starting with #) in the nccl.conf file
* Issue #1540.

Make user buffer registration problems print an INFO instead of a WARN.

Drop support for network plugin interface version 5.

Fix a race condition with split-shared communicators
 * NCCL could hang during connection setup if multiple communicators
   were grouped together that share resources.

Fix a performance regression when using NCCL_CROSS_NIC=1
 * NCCL would unnecessarily alternate rings, breaking the GPU-NIC
   associations.

Make GID index detection code more resilient
 * Dynamic GID detection code was giving up too soon if the
   detected index was not available (e.g., wasn't mapped to the
   container's sysfs).
 * Issues #1538, #1573.

Fix a race condition with non-blocking operation
 * Fix issue when creating a non-blocking communicator after a non-
   blocking collective operation on another communicator.

Fix shared memory usage on recent Blackwell GPUs.
 * Issues NVIDIA/nccl-tests#287, NVIDIA/nccl-tests#291, #1637.

Fix an error with NIC fusion and IB SHARP when recreating communicators
 * Disable the unloading of network plugins

Make the auto-merge failures in the NIC fusion non-fatal
 * This could happen when trying to merge IB and RoCE devices.

Fixes to ncclCommAbort
 * Fix hangs due to the progress thread spinning indefinitely on the
   network progress.
 * Reduce the abort time by up to two orders of magnitude.

Fix a crash when libnccl.so was dynamically unloaded
 * The RAS subsystem was missing a clean-up handler.

Fix a hang if the network plugin's test() call returns an error.

Fix a hang on heterogeneous architectures
 * Ensure we harmonize the tuning to avoid different tuning choices,
   causing a hang.

Fix double-free on failed ncclCommInitRank and ncclCommFinalize.

Fix a potential list traversal bug during a group launch of multiple
communicators
 * Issue #1599.

Unify the handling of NCCL configuration variables
 * Under rare circumstances, some variables specified in the config file
   could be ignored.


[ROCm/rccl commit: f44ac759fe]

projects/rccl/src/include/plugin/profiler/net_ib.h

@@ -0,0 +1,13 @@
+/*************************************************************************
+ * Copyright (c) 2024, NVIDIA CORPORATION. All rights reserved.
+ *
+ * See LICENSE.txt for license information
+ ************************************************************************/
+
+#ifndef NET_IB_H_
+#define NET_IB_H_
+
+#include "nccl_profiler.h"
+#include "net_ib_v1.h"
+
+#endif

projects/rccl/src/include/plugin/profiler/net_ib_v1.h

@@ -0,0 +1,34 @@
+/*************************************************************************
+ * Copyright (c) 2024, NVIDIA CORPORATION. All rights reserved.
+ *
+ * See LICENSE.txt for license information
+ ************************************************************************/
+
+#ifndef NET_IB_V1_H_
+#define NET_IB_V1_H_
+
+#define NCCL_PROFILER_NET_IB_VER 1
+
+enum {
+  ncclProfileQp = (1 << 0),
+};
+
+// The data structure version is encoded in the plugin identifier bitmask and
+// passed to NCCL core through the profiler callback. NCCL copies the plugin
+// identifier in the event descriptor before calling the profiler startEvent
+// function. The profiler should inspect the plugin id to find out the source
+// plugin as well as the version of the event struct
+typedef struct {
+  uint8_t type;        // event type (plugin defined)
+  union {
+    struct {
+      int device;      // network device id
+      uint64_t wr_id;  // work request id
+      int opcode;      // ibv opcode
+      int qpNum;       // QP number
+      size_t length;   // work request data length
+    } qp;
+  };
+} ncclProfilerNetIbDescr_v1_t;
+
+#endif

projects/rccl/src/include/plugin/profiler/net_socket.h

@@ -0,0 +1,13 @@
+/*************************************************************************
+ * Copyright (c) 2024, NVIDIA CORPORATION. All rights reserved.
+ *
+ * See LICENSE.txt for license information
+ ************************************************************************/
+
+#ifndef NET_SOCKET_H_
+#define NET_SOCKET_H_
+
+#include "nccl_profiler.h"
+#include "net_socket_v1.h"
+
+#endif

projects/rccl/src/include/plugin/profiler/net_socket_v1.h

@@ -0,0 +1,32 @@
+/*************************************************************************
+ * Copyright (c) 2024, NVIDIA CORPORATION. All rights reserved.
+ *
+ * See LICENSE.txt for license information
+ ************************************************************************/
+
+#ifndef NET_SOCKET_V1_H_
+#define NET_SOCKET_V1_H_
+
+#define NCCL_PROFILER_NET_SOCKET_VER 1
+
+enum {
+  ncclProfileSocket = (1 << 0),
+};
+
+// The data structure version is encoded in the plugin identifier bitmask and
+// passed to NCCL core through the profiler callback. NCCL copies the plugin
+// identifier in the event descriptor before calling the profiler startEvent
+// function. The profiler should inspect the plugin id to find out the source
+// plugin as well as the version of the event struct
+typedef struct {
+  uint8_t type;        // event type (plugin defined)
+  union {
+    struct {
+      int fd;
+      int op;
+      size_t length;
+    } sock;
+  };
+} ncclProfilerNetSockDescr_v1_t;
+
+#endif

projects/rccl/src/include/plugin/profiler/profiler_v1.h

@@ -0,0 +1,107 @@
+/*************************************************************************
+ * Copyright (c) 2024, NVIDIA CORPORATION. All rights reserved.
+ *
+ * See LICENSE.txt for license information
+ ************************************************************************/
+
+#ifndef PROFILER_V1_H_
+#define PROFILER_V1_H_
+
+typedef struct {
+  uint8_t type;                 // event type descriptor: ncclProfileColl, ...
+  void* parentObj;              // pointer to the profiler parent object (for coll is the group)
+  int rank;                     // originating rank
+  union {
+    struct {
+      const char* name;
+      uint64_t commHash;
+      uint64_t seqNumber;
+      uint8_t func;
+      void const* sendBuff;
+      void* recvBuff;
+      size_t count;
+      int root;
+      uint8_t datatype;
+      uint32_t op;
+      size_t trafficBytes;
+      uint8_t nMaxChannels;
+      uint8_t nWarps;
+      uint8_t algo;
+      uint8_t proto;
+      int isCollnet;
+      int isNvls;
+    } coll;
+
+    struct {
+      const char* name;
+      uint64_t commHash;
+      uint8_t func;
+      void* buff;
+      uint8_t datatype;
+      size_t count;
+      int peer;
+    } p2p;
+
+    struct {
+      pid_t pid;                // pid of the originating process
+      uint8_t channelId;        // channel id for this proxy operation
+      int peer;                 // remote rank for send/recv
+      int nSteps;               // number of steps for this proxy operation
+      int chunkSize;            // amount of data transferred by this proxy operation
+      int isSend;
+    } proxyOp;
+
+    struct {
+      int step;
+    } proxyStep;
+  };
+} ncclProfilerEventDescr_v1_t;
+
+typedef union {
+  struct {
+    size_t transSize;
+    int steps;
+  } proxyOp;
+
+  struct {
+    int appendedProxyOps;
+  } proxyCtrl;
+} ncclProfilerEventStateArgs_v1_t;
+
+typedef struct {
+  const char* name;
+
+  // init - initialize the profiler plugin
+  // Input
+  //  - context        : opaque profiler context object for separating profiler behavior across comms
+  // Output
+  //  - eActivationMask: bitmask of active events set by the plugin
+  ncclResult_t (*init)(void** context, int* eActivationMask);
+
+  // startEvent - initialize and start a new event for the supplied event descriptor inside the eventset
+  // Input
+  //  - context: opaque profiler context object
+  //  - eDescr : pointer to ncclProfilerEventDescr_t object
+  // Output
+  //  - eHandle: return event handle for supplied event descriptor object
+  ncclResult_t (*startEvent)(void* context, void** eHandle, ncclProfilerEventDescr_v1_t* eDescr);
+
+  // stopEvent - stop/finalize an event inside and event set
+  // Input
+  //  - eHandle: handle to event object
+  ncclResult_t (*stopEvent)(void* eHandle);
+
+  // recordEventState - record event state transitions and event attribute updates
+  // Input
+  //  - eHandle   : handle to event object created through startEvent
+  //  - eStateArgs: optional argument used to capture event attribute updates associated with the state transition
+  //  - eState    : event state transition
+  ncclResult_t (*recordEventState)(void* eHandle, ncclProfilerEventState_v1_t eState, ncclProfilerEventStateArgs_v1_t* eStateArgs);
+
+  // finalize - finalize the profiler plugin
+  // Input
+  //  - context: opaque profiler context object
+  ncclResult_t (*finalize)(void* context);
+} ncclProfiler_v1_t;
+
+#endif

projects/rccl/src/include/plugin/profiler/profiler_v2.h

@@ -0,0 +1,104 @@
+/*************************************************************************
+ * Copyright (c) 2024, NVIDIA CORPORATION. All rights reserved.
+ *
+ * See LICENSE.txt for license information
+ ************************************************************************/
+
+#ifndef PROFILER_V2_H_
+#define PROFILER_V2_H_
+
+typedef struct {
+  uint8_t type;                 // event type descriptor: ncclProfileColl, ...
+  void* parentObj;              // pointer to the profiler parent object (for coll is the group)
+  int rank;                     // originating rank
+  union {
+    struct {
+      const char* name;
+      uint64_t commHash;
+      uint64_t seqNumber;
+      const char* func;
+      void const* sendBuff;
+      void* recvBuff;
+      size_t count;
+      int root;
+      const char* datatype;
+      size_t trafficBytes;
+      uint8_t nMaxChannels;
+      uint8_t nWarps;
+      const char* algo;
+      const char* proto;
+    } coll;
+
+    struct {
+      const char* name;
+      uint64_t commHash;
+      const char* func;
+      void* buff;
+      const char* datatype;
+      size_t count;
+      int peer;
+    } p2p;
+
+    struct {
+      pid_t pid;                // pid of the originating process
+      uint8_t channelId;        // channel id for this proxy operation
+      int peer;                 // remote rank for send/recv
+      int nSteps;               // number of steps for this proxy operation
+      int chunkSize;            // amount of data transferred by this proxy operation
+      int isSend;
+    } proxyOp;
+
+    struct {
+      int step;
+    } proxyStep;
+  };
+} ncclProfilerEventDescr_v2_t;
+
+typedef union {
+  struct {
+    size_t transSize;
+    int steps;
+  } proxyOp;
+
+  struct {
+    int appendedProxyOps;
+  } proxyCtrl;
+} ncclProfilerEventStateArgs_v2_t;
+
+typedef struct {
+  const char* name;
+
+  // init - initialize the profiler plugin
+  // Input
+  //  - context        : opaque profiler context object for separating profiler behavior across comms
+  // Output
+  //  - eActivationMask: bitmask of active events set by the plugin
+  ncclResult_t (*init)(void** context, int* eActivationMask);
+
+  // startEvent - initialize and start a new event for the supplied event descriptor inside the eventset
+  // Input
+  //  - context: opaque profiler context object
+  //  - eDescr : pointer to ncclProfilerEventDescr_t object
+  // Output
+  //  - eHandle: return event handle for supplied event descriptor object
+  ncclResult_t (*startEvent)(void* context, void** eHandle, ncclProfilerEventDescr_v2_t* eDescr);
+
+  // stopEvent - stop/finalize an event inside and event set
+  // Input
+  //  - eHandle: handle to event object
+  ncclResult_t (*stopEvent)(void* eHandle);
+
+  // recordEventState - record event state transitions and event attribute updates
+  // Input
+  //  - eHandle   : handle to event object created through startEvent
+  //  - eStateArgs: optional argument used to capture event attribute updates associated with the state transition
+  //  - eState    : event state transition
+  ncclResult_t (*recordEventState)(void* eHandle, ncclProfilerEventState_v2_t eState, ncclProfilerEventStateArgs_v2_t* eStateArgs);
+
+  // finalize - finalize the profiler plugin
+  // Input
+  //  - context: opaque profiler context object
+  ncclResult_t (*finalize)(void* context);
+} ncclProfiler_v2_t;
+
+#endif

projects/rccl/src/include/plugin/profiler/profiler_v3.h

@@ -0,0 +1,112 @@
+/*************************************************************************
+ * Copyright (c) 2024, NVIDIA CORPORATION. All rights reserved.
+ *
+ * See LICENSE.txt for license information
+ ************************************************************************/
+
+#ifndef PROFILER_V3_H_
+#define PROFILER_V3_H_
+
+typedef struct {
+  uint8_t type;                 // event type descriptor: ncclProfileColl, ...
+  void* parentObj;              // pointer to the profiler parent object (for coll is the group)
+  int rank;                     // originating rank
+  union {
+    struct {
+      const char* name;
+      uint64_t commHash;
+      uint64_t seqNumber;
+      const char* func;
+      void const* sendBuff;
+      void* recvBuff;
+      size_t count;
+      int root;
+      const char* datatype;
+      uint8_t nMaxChannels;
+      uint8_t nWarps;
+      const char* algo;
+      const char* proto;
+    } coll;
+
+    struct {
+      const char* name;
+      uint64_t commHash;
+      const char* func;
+      void* buff;
+      const char* datatype;
+      size_t count;
+      int peer;
+    } p2p;
+
+    struct {
+      pid_t pid;                // pid of the originating process
+      uint8_t channelId;        // channel id for this proxy operation
+      int peer;                 // remote rank for send/recv
+      int nSteps;               // number of steps for this proxy operation
+      int chunkSize;            // amount of data transferred by this proxy operation
+      int isSend;
+    } proxyOp;
+
+    struct {
+      int step;
+    } proxyStep;
+
+    struct {
+      uint8_t channelId;
+    } kernelCh;
+
+    struct {
+      int64_t id;
+      void* data;
+    } netPlugin;
+  };
+} ncclProfilerEventDescr_v3_t;
+
+typedef union {
+  struct {
+    size_t transSize;
+    int steps;
+  } proxyOp;
+
+  struct {
+    int appendedProxyOps;
+  } proxyCtrl;
+} ncclProfilerEventStateArgs_v3_t;
+
+typedef struct {
+  const char* name;
+
+  // init - initialize the profiler plugin
+  // Input
+  //  - context        : opaque profiler context object for separating profiler behavior across comms
+  // Output
+  //  - eActivationMask: bitmask of active events set by the plugin
+  ncclResult_t (*init)(void** context, int* eActivationMask);
+
+  // startEvent - initialize and start a new event for the supplied event descriptor inside the eventset
+  // Input
+  //  - context: opaque profiler context object
+  //  - eDescr : pointer to ncclProfilerEventDescr_t object
+  // Output
+  //  - eHandle: return event handle for supplied event descriptor object
+  ncclResult_t (*startEvent)(void* context, void** eHandle, ncclProfilerEventDescr_v3_t* eDescr);
+
+  // stopEvent - stop/finalize an event inside and event set
+  // Input
+  //  - eHandle: handle to event object
+  ncclResult_t (*stopEvent)(void* eHandle);
+
+  // recordEventState - record event state transitions and event attribute updates
+  // Input
+  //  - eHandle   : handle to event object created through startEvent
+  //  - eStateArgs: optional argument used to capture event attribute updates associated with the state transition
+  //  - eState    : event state transition
+  ncclResult_t (*recordEventState)(void* eHandle, ncclProfilerEventState_v3_t eState, ncclProfilerEventStateArgs_v3_t* eStateArgs);
+
+  // finalize - finalize the profiler plugin
+  // Input
+  //  - context: opaque profiler context object
+  ncclResult_t (*finalize)(void* context);
+} ncclProfiler_v3_t;
+
+#endif