Sylvain Jeaugey
b6475625fb
Add support for alternating rings, allow for cross-nic rings without cross-rail communication. Add support for user buffer registration for network send/recv. Optimize aggregated operations to better utilize all channels. Add flattening for BCM PCI gen5 switches. Add support for inter-node NVLink communication Add support for port fusion in NET/IB. Add support for ReduceScatter and AllGather using Collnet. Update net API to v8. Fix hang during A2A connection.
492 line
20 KiB
C++
492 line
20 KiB
C++
/*************************************************************************
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* Copyright (c) 2016-2022, NVIDIA CORPORATION. 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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#include "topo.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, struct ncclTopoGraph** graphs, struct ncclTopoRanks* topoRanks) {
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int rank = comm->rank;
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int localRanks = comm->topo->nodes[GPU].count;
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int nChannels = comm->nChannels;
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topoRanks->nvlsHeadNum = 0;
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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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channel->collnetChain.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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for (int i=0; i<NCCL_MAX_TREE_ARITY; i++) channel->collnetChain.down[i] = -1;
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channel->collnetDirect.out = -1;
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channel->collnetDirect.headRank = -1;
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channel->collnetDirect.nHeads = 0;
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channel->collnetDirect.shift = 0;
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for (int i=0; i<NCCL_MAX_DIRECT_ARITY+1; i++) channel->collnetDirect.heads[i] = -1;
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for (int i=0; i<NCCL_MAX_DIRECT_ARITY; i++) channel->collnetDirect.up[i] = -1;
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for (int i=0; i<NCCL_MAX_DIRECT_ARITY; i++) channel->collnetDirect.down[i] = -1;
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int* ringIntra = graphs[NCCL_ALGO_RING]->intra+c*localRanks;
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int* treeIntra = graphs[NCCL_ALGO_TREE]->intra+c*localRanks;
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int* collNetIntra = graphs[NCCL_ALGO_COLLNET_CHAIN]->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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topoRanks->ringPrev[c] = (i == 0) ? -1 : ringIntra[i-1];
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topoRanks->ringNext[c] = (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 = graphs[NCCL_ALGO_TREE]->pattern == NCCL_TOPO_PATTERN_TREE ? 0 : 1;
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int child1Index = graphs[NCCL_ALGO_TREE]->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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if (collNetIntra[i] == rank) {
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channel->collnetChain.up = i == 0 ? comm->nRanks : collNetIntra[i-1];
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channel->collnetChain.down[0] = i == localRanks-1 ? -1 : collNetIntra[i+1];
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}
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}
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}
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// Duplicate channels trees
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struct ncclChannel* channel0 = comm->channels;
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struct ncclChannel* channel1 = channel0+nChannels;
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memcpy(channel1, channel0, nChannels*sizeof(struct ncclChannel));
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// Get nvls heads and the number of heads. Duplicate head is not allowed.
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for (int c = 0; c < graphs[NCCL_ALGO_NVLS]->nChannels; ++c) {
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bool addHead = true;
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int* nvlsIntra = graphs[NCCL_ALGO_NVLS]->intra + c * localRanks;
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for (int dup = 0; dup < topoRanks->nvlsHeadNum; dup++) {
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if (topoRanks->nvlsHeads[dup] == nvlsIntra[0]) {
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addHead = false;
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break;
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}
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}
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if (addHead) {
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topoRanks->nvlsHeads[topoRanks->nvlsHeadNum++] = nvlsIntra[0];
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}
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}
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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) {
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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->nNodes;
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int* send = ringSend+c*comm->nNodes;
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int* prev = ringPrev+c*comm->nRanks;
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int* next = ringNext+c*comm->nRanks;
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for (int n=0; n<nNodes; n++) {
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int recvRank = recv[n];
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int prevSendRank = send[(n-1+nNodes)%nNodes];
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prev[recvRank] = prevSendRank;
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int sendRank = send[n];
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int nextRecvRank = recv[(n+1)%nNodes];
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next[sendRank] = nextRecvRank;
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}
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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) {
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for (int n=0; n<nNodes; n++) indexes[n] = ranks[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* treePatterns) {
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const int nChannels = comm->nChannels, nNodes = comm->nNodes, node = comm->node;
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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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int* ttp, *ttc0, *ttc1;
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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 = channel0+nChannels;
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ttp = treeToParent+c*comm->nNodes;
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ttc0 = treeToChild0+c*comm->nNodes;
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ttc1 = treeToChild1+c*comm->nNodes;
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if (comm->rank == ttp[node]) {
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NCCLCHECK(setTreeUp(&channel0->tree, t0ChildType == 0 ? ttc0 : ttc1, t0u));
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NCCLCHECK(setTreeUp(&channel1->tree, t1ChildType == 0 ? ttc0 : ttc1, t1u));
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}
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if (comm->rank == ttc0[node]) {
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NCCLCHECK(setTreeDown(&channel0->tree, ttp, t0d0));
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NCCLCHECK(setTreeDown(&channel1->tree, ttp, t1d0));
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}
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if (comm->rank == ttc1[node]) {
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NCCLCHECK(setTreeDown(&channel0->tree, ttp, t0d1));
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NCCLCHECK(setTreeDown(&channel1->tree, ttp, t1d1));
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}
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if (comm->rank == ttp[node] ||
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comm->rank == ttc0[node] ||
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comm->rank == ttc1[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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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 = channel1->tree.depth = depth;
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}
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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 = 0;
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int *heads;
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NCCLCHECK(ncclCalloc(&heads, localRanks));
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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<collNetGraph->nChannels; c++) {
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int* collNetIntra = collNetGraph->intra+c*localRanks;
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int head = collNetIntra[0];
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for (int h=0; h<nHeads; h++) if (heads[h] == head) head = -1;
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if (head != -1) heads[nHeads++] = 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->collnetDirect.headRank = i; // Mark the index for deciding offset in the CUDA kernel
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channel->collnetDirect.out = comm->nRanks; // Set root of collnetDirect 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->collnetDirect.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->collnetDirect.up[nUp++] = heads[h];
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sprintf(line+strlen(line), " %d ", heads[h]);
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}
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sprintf(line+strlen(line), "heads ");
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{ // heads[] is the list of heads ordered in head order startubg with self
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int h0 = (channel->collnetDirect.headRank == -1) ? 0 : channel->collnetDirect.headRank;
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for (int h1=0; h1 < nHeads; h1++) {
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int h = (h0+h1)%nHeads;
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channel->collnetDirect.heads[h1] = heads[h];
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sprintf(line+strlen(line), " %d ", heads[h]);
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}
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}
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channel->collnetDirect.nHeads = nHeads;
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channel->collnetDirect.shift = (rank%localRanks)%nHeads; // Shift by intraRank so that leaves don't send to same head simultaneously
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channel->collnetDirect.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->collnetDirect.headRank, channel->collnetDirect.out, channel->collnetDirect.shift);
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INFO(NCCL_GRAPH, "%s", line);
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channel->collnetChain.depth = comm->nRanks/comm->nNodes;
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}
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free(heads);
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return ncclSuccess;
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}
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static ncclResult_t connectNvls(struct ncclComm* comm, int* nvlsHeads, int nHeads) {
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int headRank = -1;
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if (nHeads == 0) {
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comm->nvlsChannels = 0;
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return ncclSuccess;
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}
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for (int h = 0; h < nHeads; h++) {
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if (nvlsHeads[h * comm->nNodes + comm->node] == comm->rank) headRank = h;
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}
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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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channel->nvls.nHeads = nHeads;
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for (int h=0; h<nHeads; h++) channel->nvls.up[h] = comm->nRanks+1+h;
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for (int h=nHeads; h<NCCL_MAX_NVLS_ARITY; h++) channel->nvls.up[h] = -1;
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channel->nvls.down = comm->nRanks+1+headRank;
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channel->nvls.out = -1; // NVLS+SHARP not yet implemented.
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channel->nvls.headRank = headRank;
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channel->nvls.treeUp = channel->nvls.treeDown[0] = channel->nvls.treeDown[1] = channel->nvls.treeDown[2] = -1;
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channel->nvls.node = comm->node;
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channel->nvls.nNodes = comm->nNodes;
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if (comm->collNetSupport && channel->nvls.headRank != -1) channel->nvls.out = comm->nRanks;
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}
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// MNNVL: NVLS not yet supported
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if (comm->nNodes == 1 || comm->MNNVL) return ncclSuccess;
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// Connect Trees
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int tree0Parent, tree0Child0, tree0Child1, tree1Parent, tree1Child0, tree1Child1;
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int pc0, pc1; // ignored
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NCCLCHECK(ncclGetDtree(comm->nNodes, comm->node,
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&tree0Parent, &tree0Child0, &tree0Child1, &pc0,
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&tree1Parent, &tree1Child0, &tree1Child1, &pc1));
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int* heads = NULL;
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int treeUp[2] = { -1, -1 };
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int treeDown0[2] = { -1, -1 };
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int treeDown1[2] = { -1, -1 };
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if (comm->node == 0) {
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for (int h=0; h<nHeads; h++) {
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char line[1024];
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sprintf(line, "NVLS Head %2d:", h);
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heads = nvlsHeads+h*comm->nNodes;
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for (int n=0; n<comm->nNodes && n<20; n++) {
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sprintf(line+strlen(line), " %2d", heads[n]);
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}
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INFO(NCCL_INIT, "%s", line);
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}
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}
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// Find the heads where I'm the head rank and retain tree up/down
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for (int h=0; h<nHeads; h++) {
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heads = nvlsHeads+h*comm->nNodes;
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if (heads[comm->node] == comm->rank) {
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treeUp[0] = tree0Parent == -1 ? -1: heads[tree0Parent];
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treeDown0[0] = tree0Child0 == -1 ? -1 : heads[tree0Child0];
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treeDown1[0] = tree0Child1 == -1 ? -1 : heads[tree0Child1];
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treeUp[1] = tree1Parent == -1 ? -1 : heads[tree1Parent];
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treeDown0[1] = tree1Child0 == -1 ? -1 : heads[tree1Child0];
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treeDown1[1] = tree1Child1 == -1 ? -1 : heads[tree1Child1];
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break;
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}
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}
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// Set prev/next in all channels (NVLS compute channels work
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// orthogonally to NVLS search 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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channel->nvls.treeUp = treeUp[c%2];
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channel->nvls.treeDown[0] = channel->nvls.down;
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int ix = 1;
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if (treeDown0[c%2] != -1) channel->nvls.treeDown[ix++] = treeDown0[c%2];
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if (treeDown1[c%2] != -1) channel->nvls.treeDown[ix] = treeDown1[c%2];
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}
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struct ncclNvls* nvls0 = &comm->channels[0].nvls;
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struct ncclNvls* nvls1 = &comm->channels[1].nvls;
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INFO(NCCL_GRAPH, "NVLS Trees : %d/%d->%d->%d %d/%d->%d->%d",
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nvls0->treeDown[0], nvls0->treeDown[1], comm->rank, nvls0->treeUp,
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nvls1->treeDown[0], nvls1->treeDown[1], comm->rank, nvls1->treeUp);
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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 = 0;
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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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void exchangeValues(int* v0, int* v1) {
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int tmp = *v1;
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*v1 = *v0;
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*v0 = tmp;
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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** graphs) {
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// Gather data from all ranks
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int *ringRecv, *ringSend, *ringPrev, *ringNext, *treeToParent, *treeToChild0, *treeToChild1, *nvlsHeads;
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int nranks = comm->nRanks;
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int nNodes = comm->nNodes;
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int nChannels = comm->nChannels;
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int minHeadNum = INT_MAX;
|
|
NCCLCHECK(ncclCalloc(&ringRecv, nNodes*MAXCHANNELS));
|
|
NCCLCHECK(ncclCalloc(&ringSend, nNodes*MAXCHANNELS));
|
|
NCCLCHECK(ncclCalloc(&ringPrev, nranks*MAXCHANNELS));
|
|
NCCLCHECK(ncclCalloc(&ringNext, nranks*MAXCHANNELS));
|
|
NCCLCHECK(ncclCalloc(&treeToParent, nNodes*MAXCHANNELS));
|
|
NCCLCHECK(ncclCalloc(&treeToChild0, nNodes*MAXCHANNELS));
|
|
NCCLCHECK(ncclCalloc(&treeToChild1, nNodes*MAXCHANNELS));
|
|
NCCLCHECK(ncclCalloc(&nvlsHeads, nNodes*MAXCHANNELS));
|
|
|
|
// Alternate rings to avoid crossing rails
|
|
if (graphs[NCCL_ALGO_RING]->crossNic && (comm->nNodes % 2) == 0 && (nChannels % 2) == 0) {
|
|
for (int r=0; r<comm->nRanks; r++) {
|
|
if (comm->rankToNode[r] % 2 == 1) {
|
|
// Exchange rings
|
|
for (int c=0; c<nChannels; c+=2) {
|
|
exchangeValues(allTopoRanks[r]->ringRecv+c, allTopoRanks[r]->ringRecv+(c^1));
|
|
exchangeValues(allTopoRanks[r]->ringSend+c, allTopoRanks[r]->ringSend+(c^1));
|
|
exchangeValues(allTopoRanks[r]->ringPrev+c, allTopoRanks[r]->ringPrev+(c^1));
|
|
exchangeValues(allTopoRanks[r]->ringNext+c, allTopoRanks[r]->ringNext+(c^1));
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
for (int c=0; c<nChannels;c++) {
|
|
for (int n=0; n<nNodes; n++) {
|
|
int r = firstRanks[n];
|
|
ringRecv[c*nNodes+n] = allTopoRanks[r]->ringRecv[c];
|
|
ringSend[c*nNodes+n] = allTopoRanks[r]->ringSend[c];
|
|
treeToParent[c*nNodes+n] = allTopoRanks[r]->treeToParent[c];
|
|
treeToChild0[c*nNodes+n] = allTopoRanks[r]->treeToChild0[c];
|
|
treeToChild1[c*nNodes+n] = allTopoRanks[r]->treeToChild1[c];
|
|
}
|
|
for (int r=0; r<nranks; r++) {
|
|
ringPrev[c*nranks+r] = allTopoRanks[r]->ringPrev[c];
|
|
ringNext[c*nranks+r] = allTopoRanks[r]->ringNext[c];
|
|
}
|
|
}
|
|
|
|
for (int n = 0; n < nNodes; n++) {
|
|
int r = firstRanks[n];
|
|
if (minHeadNum > allTopoRanks[r]->nvlsHeadNum)
|
|
minHeadNum = allTopoRanks[r]->nvlsHeadNum;
|
|
}
|
|
|
|
for (int c = 0; c < minHeadNum; c++) {
|
|
for (int n = 0; n < nNodes; n++) {
|
|
int r = firstRanks[n];
|
|
nvlsHeads[c * nNodes + n] = allTopoRanks[r]->nvlsHeads[c];
|
|
}
|
|
}
|
|
|
|
// Connect rings and trees. This should also duplicate the channels.
|
|
NCCLCHECK(connectRings(comm, ringRecv, ringSend, ringPrev, ringNext));
|
|
NCCLCHECK(connectTrees(comm, treeToParent, treeToChild0, treeToChild1, treePatterns));
|
|
|
|
// Duplicate ringPrev/ringNext for ncclBuildRing
|
|
memcpy(ringPrev+nChannels*nranks, ringPrev, nChannels*nranks*sizeof(int));
|
|
memcpy(ringNext+nChannels*nranks, ringNext, nChannels*nranks*sizeof(int));
|
|
|
|
// Set ring prev/next for my rank
|
|
for (int c=0; c<nChannels; c++) {
|
|
struct ncclChannel* channel0 = comm->channels+c;
|
|
struct ncclChannel* channel1 = channel0+nChannels;
|
|
channel0->ring.prev = channel1->ring.prev = ringPrev[c*nranks+comm->rank];
|
|
channel0->ring.next = channel1->ring.next = ringNext[c*nranks+comm->rank];
|
|
}
|
|
|
|
// Duplication should be complete now
|
|
nChannels = comm->nChannels = std::min(MAXCHANNELS,nChannels*2);
|
|
|
|
// Setup CollNet
|
|
if (comm->collNetSupport == 1) {
|
|
struct ncclTopoGraph* collNetGraph = graphs[NCCL_ALGO_COLLNET_DIRECT];
|
|
// Add more channels to saturate intra-node bandwidth, except the 1 PPN case
|
|
if (collNetGraph->bwIntra > collNetGraph->bwInter && comm->nRanks > comm->nNodes) {
|
|
int collNetNchannels = std::min(MAXCHANNELS, nChannels+nChannels/2);
|
|
nChannels = comm->nChannels = copyChannels(comm, nChannels, collNetNchannels, ringPrev, ringNext);
|
|
}
|
|
NCCLCHECK(connectCollNet(comm, collNetGraph));
|
|
}
|
|
|
|
// Use 4 compute channels per search channel to reach peak BW on <8 PPN
|
|
if (comm->minCompCap == 90 && comm->nNodes > 1 && graphs[NCCL_ALGO_RING]->bwIntra > 45.0 && nChannels < 16) {
|
|
nChannels = comm->nChannels = copyChannels(comm, nChannels, 2*nChannels, ringPrev, ringNext);
|
|
}
|
|
|
|
// Honor NCCL_MIN_NRINGS/NCCL_MAX_NRINGS.
|
|
// We permit combining max, then min, to only use the first channels, then duplicate them.
|
|
if (comm->sharedRes->owner != comm) {
|
|
/* child comm #channels cannot exceed top parent #channels. */
|
|
nChannels = comm->nChannels = std::min(std::min(std::min(ncclMaxNchannels(), nChannels), comm->config.maxCTAs), comm->sharedRes->tpNChannels);
|
|
nChannels = comm->nChannels = copyChannels(comm, nChannels, std::min(std::max(ncclMinNchannels(), comm->config.minCTAs), comm->sharedRes->tpNChannels), ringPrev, ringNext);
|
|
} else {
|
|
nChannels = comm->nChannels = std::min(std::min(ncclMaxNchannels(), nChannels), comm->config.maxCTAs);
|
|
nChannels = comm->nChannels = copyChannels(comm, nChannels, std::max(ncclMinNchannels(), comm->config.minCTAs), ringPrev, ringNext);
|
|
}
|
|
|
|
comm->collChannels = comm->nChannels;
|
|
// Support maximal channel usage for aggregation
|
|
if (comm->nChannels < comm->nvlsChannels) {
|
|
nChannels = comm->nChannels = copyChannels(comm, comm->nChannels, comm->nvlsChannels, ringPrev, ringNext);
|
|
}
|
|
NCCLCHECK(connectNvls(comm, nvlsHeads, minHeadNum));
|
|
|
|
// Create rings array and check all is fine
|
|
NCCLCHECK(ncclBuildRings(nChannels, rings, comm->rank, comm->nRanks, ringPrev, ringNext));
|
|
|
|
free(ringRecv);
|
|
free(ringSend);
|
|
free(ringPrev);
|
|
free(ringNext);
|
|
free(treeToParent);
|
|
free(treeToChild0);
|
|
free(treeToChild1);
|
|
free(nvlsHeads);
|
|
|
|
return ncclSuccess;
|
|
}
|