Wenkai Du
328 行
14 KiB
C++
328 行
14 KiB
C++
/*************************************************************************
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* Copyright (c) 2016-2021, NVIDIA CORPORATION. All rights reserved.
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* Modifications Copyright (c) 2019-2021 Advanced Micro Devices, Inc. All rights reserved.
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*
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* See LICENSE.txt for license information
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************************************************************************/
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#include "comm.h"
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#include "graph.h"
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#include "trees.h"
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#include "rings.h"
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/******************************************************************/
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/********************* Internode connection ***********************/
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/******************************************************************/
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ncclResult_t ncclTopoPreset(struct ncclComm* comm,
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struct ncclTopoGraph* treeGraph, struct ncclTopoGraph* ringGraph,
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struct ncclTopoRanks* topoRanks) {
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int rank = comm->rank;
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int localRanks = comm->localRanks;
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int nChannels = comm->nChannels;
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for (int c=0; c<nChannels; c++) {
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struct ncclChannel* channel = comm->channels+c;
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channel->ring.prev = channel->ring.next = -1;
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channel->tree.up = -1;
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for (int i=0; i<NCCL_MAX_TREE_ARITY; i++) channel->tree.down[i] = -1;
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channel->collTree.out = -1;
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channel->collTree.headRank = -1;
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channel->collTree.nHeads = 0;
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channel->collTree.shift = 0;
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for (int i=0; i<NCCL_MAX_DIRECT_ARITY; i++) channel->collTree.up[i] = -1;
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for (int i=0; i<NCCL_MAX_DIRECT_ARITY; i++) channel->collTree.down[i] = -1;
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int* ringIntra = ringGraph->intra+c*localRanks;
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int* treeIntra = treeGraph->intra+c*localRanks;
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for (int i=0; i<localRanks; i++) {
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if (ringIntra[i] == rank) {
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topoRanks->ringRecv[c] = ringIntra[0];
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topoRanks->ringSend[c] = ringIntra[localRanks-1];
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channel->ring.prev = (i == 0) ? -1 : ringIntra[i-1];
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channel->ring.next = (i == localRanks-1) ? -1 : ringIntra[i+1];
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}
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if (treeIntra[i] == rank) {
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int parentIndex = 0;
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int child0Index = treeGraph->pattern == NCCL_TOPO_PATTERN_TREE ? 0 : 1;
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int child1Index = treeGraph->pattern == NCCL_TOPO_PATTERN_SPLIT_TREE ? 1 : 0;
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topoRanks->treeToParent[c] = treeIntra[parentIndex];
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topoRanks->treeToChild0[c] = treeIntra[child0Index];
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topoRanks->treeToChild1[c] = treeIntra[child1Index];
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channel->tree.up = i == 0 ? -1 : treeIntra[i-1];
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channel->tree.down[0] = i == localRanks-1 ? -1 : treeIntra[i+1];
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}
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}
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topoRanks->ringPrev[c] = channel->ring.prev;
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topoRanks->ringNext[c] = channel->ring.next;
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}
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// Duplicate channels rings/trees
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struct ncclChannel* channel0 = comm->channels;
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struct ncclChannel* channel1 = (nChannels > MAXCHANNELS/2) ? 0 : channel0+nChannels;
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if (channel1) memcpy(channel1, channel0, nChannels*sizeof(struct ncclChannel));
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return ncclSuccess;
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}
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static ncclResult_t connectRings(struct ncclComm* comm, int* ringRecv, int* ringSend, int* ringPrev, int* ringNext, int* firstRanks) {
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int nChannels = comm->nChannels;
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int nNodes = comm->nNodes;
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for (int c=0; c<nChannels; c++) {
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int* recv = ringRecv+c*comm->nRanks;
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int* send = ringSend+c*comm->nRanks;
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int* prev = ringPrev+c*comm->nRanks;
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int* next = ringNext+c*comm->nRanks;
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struct ncclChannel* channel0 = comm->channels+c;
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struct ncclChannel* channel1 = (nChannels > MAXCHANNELS/2) ? 0 : channel0+nChannels;
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for (int n=0; n<nNodes; n++) {
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int recvRank = recv[firstRanks[n]];
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int prevSendRank = send[firstRanks[(n-1+nNodes)%nNodes]];
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prev[recvRank] = prevSendRank;
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if (comm->rank == recvRank) {
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channel0->ring.prev = prevSendRank;
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if (channel1) channel1->ring.prev = prevSendRank;
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}
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int sendRank = send[firstRanks[n]];
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int nextRecvRank = recv[firstRanks[(n+1)%nNodes]];
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next[sendRank] = nextRecvRank;
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if (comm->rank == sendRank) {
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channel0->ring.next = nextRecvRank;
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if (channel1) channel1->ring.next = nextRecvRank;
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}
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}
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TRACE(NCCL_GRAPH, "Ring %d : %d -> %d -> %d", c, channel0->ring.prev, comm->rank, channel0->ring.next);
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if (channel1) TRACE(NCCL_GRAPH, "Ring %d : %d -> %d -> %d", c+nChannels, channel1->ring.prev, comm->rank, channel1->ring.next);
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}
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return ncclSuccess;
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}
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static ncclResult_t getIndexes(int* ranks, int* indexes, int nNodes, int* firstRanks) {
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for (int n=0; n<nNodes; n++) indexes[n] = ranks[firstRanks[n]];
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return ncclSuccess;
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}
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static ncclResult_t setTreeUp(struct ncclTree* tree, int* indexes, int u) {
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if (u == -1) return ncclSuccess;
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tree->up = indexes[u];
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return ncclSuccess;
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}
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static ncclResult_t setTreeDown(struct ncclTree* tree, int* indexes, int d) {
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if (d == -1) return ncclSuccess;
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int x = 0;
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while (x < NCCL_MAX_TREE_ARITY && tree->down[x] >= 0) x++;
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if (x == NCCL_MAX_TREE_ARITY) {
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WARN("Internal error : tree already has %d children (%d %d %d)", x, tree->down[0], tree->down[1], tree->down[2]);
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return ncclInternalError;
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}
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tree->down[x] = indexes[d];
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return ncclSuccess;
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}
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static ncclResult_t connectTrees(struct ncclComm* comm, int* treeToParent, int* treeToChild0, int* treeToChild1, int* firstRanks, int* treePatterns) {
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const int nChannels = comm->nChannels, nNodes = comm->nNodes, node = comm->node;
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int* ranksToParent, *ranksToChild0, *ranksToChild1;
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NCCLCHECK(ncclCalloc(&ranksToParent, nNodes));
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NCCLCHECK(ncclCalloc(&ranksToChild0, nNodes));
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NCCLCHECK(ncclCalloc(&ranksToChild1, nNodes));
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// Compute tree depth. Not an exact value but a good approximation in most
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// cases
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int depth = comm->nRanks/nNodes - 1 + log2i(nNodes);
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int t0u, t0d0, t0d1, t0ChildType, t1u, t1d0, t1d1, t1ChildType;
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NCCLCHECK(ncclGetDtree(nNodes, node, &t0u, &t0d0, &t0d1, &t0ChildType, &t1u, &t1d0, &t1d1, &t1ChildType));
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for (int c=0; c<nChannels; c++) {
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struct ncclChannel* channel0 = comm->channels+c;
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struct ncclChannel* channel1 = (nChannels > MAXCHANNELS/2) ? 0 : channel0+nChannels;
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NCCLCHECK(getIndexes(treeToParent+c*comm->nRanks, ranksToParent, nNodes, firstRanks));
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NCCLCHECK(getIndexes(treeToChild0+c*comm->nRanks, ranksToChild0, nNodes, firstRanks));
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NCCLCHECK(getIndexes(treeToChild1+c*comm->nRanks, ranksToChild1, nNodes, firstRanks));
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if (comm->rank == ranksToParent[node]) {
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NCCLCHECK(setTreeUp(&channel0->tree, t0ChildType == 0 ? ranksToChild0 : ranksToChild1, t0u));
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if (channel1) NCCLCHECK(setTreeUp(&channel1->tree, t1ChildType == 0 ? ranksToChild0 : ranksToChild1, t1u));
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}
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if (comm->rank == ranksToChild0[node]) {
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NCCLCHECK(setTreeDown(&channel0->tree, ranksToParent, t0d0));
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if (channel1) NCCLCHECK(setTreeDown(&channel1->tree, ranksToParent, t1d0));
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}
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if (comm->rank == ranksToChild1[node]) {
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NCCLCHECK(setTreeDown(&channel0->tree, ranksToParent, t0d1));
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if (channel1) NCCLCHECK(setTreeDown(&channel1->tree, ranksToParent, t1d1));
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}
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if (comm->rank == ranksToParent[node] ||
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comm->rank == ranksToChild0[node] ||
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comm->rank == ranksToChild1[node]) {
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INFO(NCCL_GRAPH, "Tree %d : %d -> %d -> %d/%d/%d", c, channel0->tree.up, comm->rank, channel0->tree.down[0], channel0->tree.down[1], channel0->tree.down[2]);
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if (channel1) INFO(NCCL_GRAPH, "Tree %d : %d -> %d -> %d/%d/%d", c+nChannels, channel1->tree.up, comm->rank, channel1->tree.down[0], channel1->tree.down[1], channel1->tree.down[2]);
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}
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channel0->tree.depth = depth;
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if (channel1) channel1->tree.depth = depth;
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}
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free(ranksToParent);
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free(ranksToChild0);
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free(ranksToChild1);
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return ncclSuccess;
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}
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static ncclResult_t connectCollNet(struct ncclComm* comm, struct ncclTopoGraph* collNetGraph) {
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int rank = comm->rank;
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int localRanks = comm->localRanks;
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int nHeads = collNetGraph->nChannels;
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int *heads;
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NCCLCHECK(ncclCalloc(&heads, nHeads));
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// Find all head ranks
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// Head index is always 0
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for (int c=0; c<nHeads; c++) {
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int* collNetIntra = collNetGraph->intra+c*localRanks;
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heads[c] = collNetIntra[0];
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}
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// For all channels
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for (int c=0; c<comm->nChannels; c++) {
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struct ncclChannel* channel = comm->channels+c;
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char line[1024];
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sprintf(line, "CollNet channel %d rank %d ", c, rank);
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int nDown = 0;
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for (int i=0; i<nHeads; i++) {
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if (rank == heads[i]) { // is head
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channel->collTree.headRank = i; // Mark the index for deciding offset in the CUDA kernel
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channel->collTree.out = comm->nRanks; // Set root of collTree to id nranks
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int* collNetIntra = collNetGraph->intra+i*localRanks;
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sprintf(line+strlen(line), "down ");
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for (int r=0; r<localRanks; r++) {
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if (collNetIntra[r] == rank) continue;
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channel->collTree.down[nDown++] = collNetIntra[r]; // connect to all peers
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sprintf(line+strlen(line), " %d ", collNetIntra[r]);
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}
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sprintf(line+strlen(line), "nDown %d ", nDown);
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break;
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}
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}
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// Connect to all heads
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int nUp = 0;
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sprintf(line+strlen(line), "up ");
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for (int h=0; h<nHeads; h++) {
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if (rank == heads[h]) continue;
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channel->collTree.up[nUp++] = heads[h];
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sprintf(line+strlen(line), " %d ", heads[h]);
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}
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channel->collTree.nHeads = nHeads;
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channel->collTree.shift = (rank%localRanks)%nHeads; // Shift by intraRank so that leaves don't send to same head simultaneously
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channel->collTree.depth = (nUp == 0 && nDown == 0) ? 1 : 2;
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sprintf(line+strlen(line), "nUp %d nHeads %d ", nUp, nHeads);
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sprintf(line+strlen(line), "headRank %d out %d shift %d", channel->collTree.headRank, channel->collTree.out, channel->collTree.shift);
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INFO(NCCL_GRAPH, "%s", line);
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}
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free(heads);
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return ncclSuccess;
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}
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// Legacy naming
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NCCL_PARAM(MinNrings, "MIN_NRINGS", -2);
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NCCL_PARAM(MaxNrings, "MAX_NRINGS", -2);
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// New naming
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NCCL_PARAM(MinNchannels, "MIN_NCHANNELS", -2);
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NCCL_PARAM(MaxNchannels, "MAX_NCHANNELS", -2);
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int ncclMinNchannels() {
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int minNchannels = 2;
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if (ncclParamMinNrings() != -2) minNchannels = ncclParamMinNrings();
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if (ncclParamMinNchannels() != -2) minNchannels = ncclParamMinNchannels();
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if (minNchannels > MAXCHANNELS) {
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WARN("User asked for a minimum of %d channels, limiting to %d", minNchannels, MAXCHANNELS);
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minNchannels = MAXCHANNELS;
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}
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if (minNchannels < 0) minNchannels = 0;
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return minNchannels;
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}
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int ncclMaxNchannels() {
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int maxNchannels = MAXCHANNELS;
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if (ncclParamMaxNrings() != -2) maxNchannels = ncclParamMaxNrings();
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if (ncclParamMaxNchannels() != -2) maxNchannels = ncclParamMaxNchannels();
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if (maxNchannels > MAXCHANNELS) maxNchannels = MAXCHANNELS;
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if (maxNchannels < 1) {
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WARN("User asked for a maximum of %d channels, setting it to 1", maxNchannels);
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maxNchannels = 1;
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}
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return maxNchannels;
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}
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static int copyChannels(struct ncclComm* comm, int start, int end, int* ringPrev, int* ringNext) {
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int nranks = comm->nRanks;
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int c;
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for (c=start; c<end; c++) {
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memcpy(ringPrev+c*nranks, ringPrev+(c-start)*nranks, nranks*sizeof(int));
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memcpy(ringNext+c*nranks, ringNext+(c-start)*nranks, nranks*sizeof(int));
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memcpy(comm->channels+c, comm->channels+c-start, sizeof(struct ncclChannel));
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}
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return c;
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}
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ncclResult_t ncclTopoPostset(struct ncclComm* comm, int* firstRanks, int* treePatterns, struct ncclTopoRanks** allTopoRanks, int* rings, struct ncclTopoGraph* collNetGraph, int nc) {
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// Gather data from all ranks
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int *ringRecv, *ringSend, *ringPrev, *ringNext, *treeToParent, *treeToChild0, *treeToChild1;
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int nranks = comm->nRanks;
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int nChannels = comm->nChannels;
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NCCLCHECK(ncclCalloc(&ringRecv, nranks*MAXCHANNELS));
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NCCLCHECK(ncclCalloc(&ringSend, nranks*MAXCHANNELS));
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NCCLCHECK(ncclCalloc(&ringPrev, nranks*MAXCHANNELS));
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NCCLCHECK(ncclCalloc(&ringNext, nranks*MAXCHANNELS));
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NCCLCHECK(ncclCalloc(&treeToParent, nranks*MAXCHANNELS));
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NCCLCHECK(ncclCalloc(&treeToChild0, nranks*MAXCHANNELS));
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NCCLCHECK(ncclCalloc(&treeToChild1, nranks*MAXCHANNELS));
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for (int i=0; i<nranks; i++) {
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for (int c=0; c<nChannels;c++) {
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ringRecv[c*nranks+i] = allTopoRanks[i]->ringRecv[c];
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ringSend[c*nranks+i] = allTopoRanks[i]->ringSend[c];
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ringPrev[c*nranks+i] = allTopoRanks[i]->ringPrev[c];
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ringNext[c*nranks+i] = allTopoRanks[i]->ringNext[c];
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treeToParent[c*nranks+i] = allTopoRanks[i]->treeToParent[c];
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treeToChild0[c*nranks+i] = allTopoRanks[i]->treeToChild0[c];
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treeToChild1[c*nranks+i] = allTopoRanks[i]->treeToChild1[c];
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}
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}
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// Connect rings and trees. This should also duplicate the channels.
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NCCLCHECK(connectRings(comm, ringRecv, ringSend, ringPrev, ringNext, firstRanks));
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NCCLCHECK(connectTrees(comm, treeToParent, treeToChild0, treeToChild1, firstRanks, treePatterns));
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// Duplicate ringPrev/ringNext for ncclBuildRing
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if (nChannels <= MAXCHANNELS/2) memcpy(ringPrev+nChannels*nranks, ringPrev, nChannels*nranks*sizeof(int));
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if (nChannels <= MAXCHANNELS/2) memcpy(ringNext+nChannels*nranks, ringNext, nChannels*nranks*sizeof(int));
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// Get number of channels after duplication
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nc *= comm->nChannels;
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nc = std::min((int)ncclMaxNchannels(), nc);
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// Duplication should be complete now
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nChannels = comm->nChannels = std::min(MAXCHANNELS, (nChannels <= MAXCHANNELS/2) ? nChannels*2 : nChannels);
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// Setup CollNet
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if (comm->collNetSupport == 1) {
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// Add more channels to saturate intra-node bandwidth, except the 1 PPN case
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if (collNetGraph->speedIntra > collNetGraph->speedInter && comm->nRanks > comm->nNodes) {
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int collNetNchannels = std::min(MAXCHANNELS, nChannels+nChannels/2);
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nChannels = comm->nChannels = copyChannels(comm, nChannels, collNetNchannels, ringPrev, ringNext);
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}
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NCCLCHECK(connectCollNet(comm, collNetGraph));
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}
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// Honor NCCL_MIN_NRINGS/NCCL_MAX_NRINGS.
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// We permit combining max, then min, to only use the first channels, then duplicate them.
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nChannels = comm->nChannels = std::min((int)ncclMaxNchannels(), nChannels);
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nChannels = comm->nChannels = copyChannels(comm, nChannels, std::max(nc, ncclMinNchannels()), ringPrev, ringNext);
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// Create rings array and check all is fine
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NCCLCHECK(ncclBuildRings(nChannels, rings, comm->rank, comm->nRanks, ringPrev, ringNext));
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free(ringRecv);
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free(ringSend);
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free(ringPrev);
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free(ringNext);
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free(treeToParent);
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free(treeToChild0);
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free(treeToChild1);
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return ncclSuccess;
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}
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