Kamil Iskra
5b471d77b2
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.
[ROCm/rccl commit: 3ea7eedf3b]
98 lines
3.3 KiB
C
98 lines
3.3 KiB
C
/*************************************************************************
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* Copyright (c) 2023, NVIDIA CORPORATION. All rights reserved.
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* Copyright (c) 2023, Meta Platforms, Inc. and affiliates.
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*
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* See LICENSE.txt for license information
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************************************************************************/
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#ifndef NCCL_TUNER_H_
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#define NCCL_TUNER_H_
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#include <stdint.h>
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#include <stdlib.h>
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#include "common.h"
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#include "err.h"
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#define NCCL_NUM_FUNCTIONS 5 // Send/Recv not included for now
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typedef enum {
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ncclFuncBroadcast = 0,
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ncclFuncReduce = 1,
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ncclFuncAllGather = 2,
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ncclFuncReduceScatter = 3,
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ncclFuncAllReduce = 4,
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ncclFuncSendRecv = 5,
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ncclFuncSend = 6,
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ncclFuncRecv = 7,
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ncclNumFuncs = 8
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} ncclFunc_t;
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#define NCCL_NUM_ALGORITHMS 7 // Tree/Ring/CollNet*
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#define NCCL_ALGO_UNDEF -1
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#define NCCL_ALGO_TREE 0
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#define NCCL_ALGO_RING 1
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#define NCCL_ALGO_COLLNET_DIRECT 2
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#define NCCL_ALGO_COLLNET_CHAIN 3
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#define NCCL_ALGO_NVLS 4
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#define NCCL_ALGO_NVLS_TREE 5
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#define NCCL_ALGO_PAT 6
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#define NCCL_NUM_PROTOCOLS 3 // Simple/LL/LL128
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#define NCCL_PROTO_UNDEF -1
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#define NCCL_PROTO_LL 0
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#define NCCL_PROTO_LL128 1
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#define NCCL_PROTO_SIMPLE 2
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#define NCCL_ALGO_PROTO_IGNORE -1.0
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// API to be implemented by external tuner
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typedef struct {
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// Name of the tuner
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const char* name;
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// Initializes tuner states.
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// Inputs:
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// - nRanks: number of ranks in current communicator. Each communicator initialize its own tuner.
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// - nNodes: number of nodes in current communicator.
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// - logFunction: a logFunction can be useful to integrate logging together with NCCL core.
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// Outputs:
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// - context: tuner context object
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ncclResult_t (*init)(size_t nRanks, size_t nNodes, ncclDebugLogger_t logFunction, void **context);
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// Gets info (algo, protocol, number of ctas and threads) for a given collective.
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// Inputs:
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// - context: tuner context object
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// - collType: collective type , e.g., allreduce, allgather…
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// - nBytes: collective size in bytes
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// - numPipeOps: number of operations in the group
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// - numAlgo: number of algorithms in collCostTable
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// - numProto: number of protocols in collCostTable
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// - regBuff: can register user buffer
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//
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// Outputs:
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// - nChannels: number of channels (hence SMs) to be used.
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//
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// InOut:
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// - collCostTable: collective cost table, generated by NCCL core, containing algo|proto|time entries for collType.
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// NCCL core sets ignored algo/proto cost table entries to -1.0 (NCCL_ALGO_PROTO_IGNORE).
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//
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// If getCollInfo() does not return ncclSuccess, NCCL will fall back to the
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// default tuning for the given collective.
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// Also, the plugin is allowed to not set any output, or set only the
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// algorithm and protocol, but not only the algorithm or only the protocol.
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// Unset fields will be set automatically by NCCL.
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ncclResult_t (*getCollInfo)(void* context, ncclFunc_t collType, size_t nBytes,
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int numPipeOps, float** collCostTable, int numAlgo, int numProto,
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int regBuff, int* nChannels);
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// Terminates the plugin and cleans up any resources that the plugin allocated.
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// context: tuner context object
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ncclResult_t (*destroy)(void* context);
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} ncclTuner_v4_t;
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typedef ncclTuner_v4_t ncclTuner_t;
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#define NCCL_TUNER_PLUGIN_SYMBOL "ncclTunerPlugin_v4"
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#endif
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