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da3b197d6cd2a8487f5ed778191f790a3c3cc24e
rocm-systems/src/graph/search.cc
T

1009 строки
39 KiB
C++
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/*************************************************************************
* Copyright (c) 2016-2020, NVIDIA CORPORATION. All rights reserved.
* Modifications Copyright (c) 2019-2020 Advanced Micro Devices, Inc. All rights reserved.
*
* See LICENSE.txt for license information
************************************************************************/
#include "core.h"
#include "graph.h"
#include "topo.h"
#include "xml.h"
#include <math.h>
// Initialize system->maxWidth. This is the per-channel (i.e. per-SM)
// max speed.
static float getMaxWidth(struct ncclTopoSystem* system, struct ncclTopoNode* gpu, int type) {
float maxWidth = 0.0;
for (int i=0; i<system->nodes[type].count; i++) {
struct ncclTopoLinkList* path = gpu->paths[type]+i;
float width = path->width;
if (path->count == 0) continue;
maxWidth = std::max(maxWidth, width);
}
return maxWidth;
}
ncclResult_t ncclTopoSearchInit(struct ncclTopoSystem* system) {
system->maxWidth = 0.0;
int inter = system->nodes[NET].count;
if (inter == 0 && system->nodes[GPU].count == 1) {
system->maxWidth = LOC_WIDTH;
return ncclSuccess;
}
for (int g=0; g<system->nodes[GPU].count; g++) {
struct ncclTopoNode* gpu = system->nodes[GPU].nodes+g;
system->maxWidth = std::max(system->maxWidth, getMaxWidth(system, gpu, inter ? NET : GPU));
}
return ncclSuccess;
}
static ncclResult_t findRevLink(struct ncclTopoNode* node1, struct ncclTopoNode* node2, struct ncclTopoLink** revLink) {
for (int l=0; l<node2->nlinks; l++) {
struct ncclTopoLink* link = node2->links+l;
if (link->remNode == node1) {
*revLink = link;
return ncclSuccess;
}
}
WARN("Could not find rev link for %d/%d -> %d/%d\n", node1->type, node1->id, node2->type, node2->id);
return ncclInternalError;
}
// This is unfortunately needed since manipulating floats often results in rounding errors.
#define SUB_ROUND(a, b) (a = roundf((a-b)*1000)/1000)
static ncclResult_t followPath(struct ncclTopoLinkList* path, struct ncclTopoNode* start, int maxSteps, float speed, int* steps) {
float pciSpeed = speed;
for (int step=0; step<path->count; step++) {
struct ncclTopoNode* node = path->list[step]->remNode;
if (node->type == CPU) {
// Account for P2P inefficiency through Intel CPU RC
if (path->type == PATH_PHB && start->type == GPU &&
node->cpu.arch == NCCL_TOPO_CPU_ARCH_X86 &&
node->cpu.vendor == NCCL_TOPO_CPU_VENDOR_INTEL) {
pciSpeed = INTEL_P2P_OVERHEAD(speed);
}
}
}
struct ncclTopoNode* node = start;
for (int step=0; step<maxSteps; step++) {
struct ncclTopoLink* link = path->list[step];
struct ncclTopoLink* revLink = NULL;
float fwSpeed = link->type == LINK_PCI ? pciSpeed : speed;
float revSpeed = 0;
if (link->remNode->type == GPU && link->remNode->gpu.cudaCompCap < 80 && start->type != GPU) {
if (revLink == NULL) NCCLCHECK(findRevLink(node, link->remNode, &revLink));
revSpeed += fwSpeed/8;
}
if (link->remNode->type == CPU && link->type == LINK_NVL) {
if (revLink == NULL) NCCLCHECK(findRevLink(node, link->remNode, &revLink));
revSpeed += fwSpeed;
}
if (link->width < fwSpeed || (revSpeed && revLink->width < revSpeed)) { *steps = step; return ncclSuccess; }
SUB_ROUND(link->width, fwSpeed);
if (revSpeed) SUB_ROUND(revLink->width, revSpeed);
node = link->remNode;
}
*steps = maxSteps;
return ncclSuccess;
}
// Try to go from node type1/index1 to no type2/index2. mult indicates whether we are counting the bandwidth (1) or undoing (-1).
static ncclResult_t ncclTopoFollowPath(struct ncclTopoSystem* system, struct ncclTopoGraph* graph, int type1, int index1, int type2, int index2, int mult, struct ncclTopoNode** node) {
// First handle easy cases
*node = system->nodes[type2].nodes+index2;
if (type1 == -1) return ncclSuccess;
struct ncclTopoNode* node1 = system->nodes[type1].nodes+index1;
struct ncclTopoLinkList* path = node1->paths[type2]+index2;
if (path->count == 0 ) return ncclSuccess;
// Now check link type
*node = NULL;
int intra = type1 == GPU && type2 == GPU;
float speed = intra ? graph->speedIntra : graph->speedInter;
int type = intra ? graph->typeIntra : graph->typeInter;
if (mult == 1 && (path->type > type)) return ncclSuccess;
speed *= mult;
// Check there is enough bandwidth on paths.
int step = 0;
NCCLCHECK(followPath(path, node1, path->count, speed, &step));
if (step < path->count) goto rewind;
// Enough bandwidth : return destination node.
graph->nHops += mult*path->count;
*node = system->nodes[type2].nodes+index2;
return ncclSuccess;
rewind:
// Not enough bandwidth : rewind and exit.
NCCLCHECK(followPath(path, node1, step, -speed, &step));
return ncclSuccess;
}
static int gpuPciWidth(struct ncclTopoNode* gpu) {
for (int l=0; l<gpu->nlinks; l++) {
struct ncclTopoLink* gpuLink = gpu->links+l;
if (gpuLink->type != LINK_PCI) continue;
struct ncclTopoNode* pci = gpuLink->remNode;
for (int l=0; l<pci->nlinks; l++) {
struct ncclTopoLink* pciLink = pci->links+l;
if (pciLink->remNode != gpu) continue;
return std::min(gpuLink->width, pciLink->width);
}
}
return -1;
}
/* Choose the order in which we try next GPUs. This is critical for the search
to quickly converge to the best solution even if it eventually times out. */
struct ncclGpuScore {
int g; // Retain the index
int startIndex; // Least important
int intraNhops;
int intraWidth;
int interNhops;
int interPciWidth;
int interWidth; // Most important
};
static int cmpScore(const void * g1, const void * g2) {
struct ncclGpuScore *s1 = (struct ncclGpuScore*)g1;
struct ncclGpuScore *s2 = (struct ncclGpuScore*)g2;
int d;
if ((d = (s2->interWidth - s1->interWidth))) return d;
if ((d = (s2->interPciWidth - s1->interPciWidth))) return d;
if ((d = (s1->interNhops - s2->interNhops))) return d;
if ((d = (s2->intraWidth - s1->intraWidth))) return d;
if ((d = (s1->intraNhops - s2->intraNhops))) return d;
return s1->startIndex - s2->startIndex;
}
static int cmpIntraScores(struct ncclGpuScore* scores, int count) {
int intraWidth = scores[0].intraWidth;
int intraNhops = scores[0].intraNhops;
for (int i=1; i<count; i++) {
if (scores[i].intraWidth != intraWidth || scores[i].intraNhops != intraNhops) return 1;
}
return 0;
}
static ncclResult_t getGpuIndex(struct ncclTopoSystem* system, int rank, int* index) {
for (int g=0; g<system->nodes[GPU].count; g++) {
if (system->nodes[GPU].nodes[g].gpu.rank == rank) {
*index = g;
return ncclSuccess;
}
}
WARN("Could not find gpu rank %d\n", rank);
return ncclInternalError;
}
static ncclResult_t getNetIndex(struct ncclTopoSystem* system, int64_t id, int* index) {
for (int n=0; n<system->nodes[NET].count; n++) {
if (system->nodes[NET].nodes[n].id == id) {
*index = n;
return ncclSuccess;
}
}
WARN("Could not find net id %lx\n", id);
return ncclInternalError;
}
static ncclResult_t getNetPaths(struct ncclTopoSystem* system, struct ncclTopoGraph* graph, struct ncclTopoLinkList** netPaths) {
int netId = graph->inter[graph->nChannels*2];
int n;
NCCLCHECK(getNetIndex(system, netId, &n));
*netPaths=system->nodes[NET].nodes[n].paths[GPU];
return ncclSuccess;
}
ncclResult_t ncclTopoSearchNextGpuSort(struct ncclTopoSystem* system, struct ncclTopoGraph* graph, struct ncclTopoNode* gpu, int* next, int* countPtr, int sortNet) {
const uint64_t flag = 1ULL<<(graph->nChannels);
int ngpus = system->nodes[GPU].count;
struct ncclTopoLinkList* paths = gpu->paths[GPU];
struct ncclTopoLinkList* netPaths = NULL;
if (sortNet) NCCLCHECK(getNetPaths(system, graph, &netPaths));
struct ncclGpuScore scores[NCCL_TOPO_MAX_NODES];
memset(scores, 0, ngpus*sizeof(struct ncclGpuScore));
int start = gpu-system->nodes[GPU].nodes;
int count = 0;
for (int i=1; i<ngpus; i++) {
int g = (start+i)%ngpus;
if (paths[g].count == 0) continue; // There is no path to that GPU
if (system->nodes[GPU].nodes[g].used & flag) continue;
scores[count].g = g;
scores[count].startIndex = i;
scores[count].intraNhops = paths[g].count;
scores[count].intraWidth = paths[g].width;
if (netPaths) {
scores[count].interNhops = netPaths[g].count;
scores[count].interPciWidth = gpuPciWidth(system->nodes[GPU].nodes+g);
scores[count].interWidth = netPaths[g].width;
}
count++;
}
// Sort GPUs
qsort(scores, count, sizeof(struct ncclGpuScore), cmpScore);
// Check if all have the same intra-node score in which case we go reverse for sortNet = -1
if (sortNet == -1 && cmpIntraScores(scores, count) == 0) {
for (int i=0; i<count; i++) next[i] = scores[count-1-i].g;
} else {
for (int i=0; i<count; i++) next[i] = scores[i].g;
}
*countPtr = count;
return ncclSuccess;
}
ncclResult_t ncclTopoSearchRec(struct ncclTopoSystem* system, struct ncclTopoGraph* graph, struct ncclTopoGraph* saveGraph, int* time);
// Try to keep all searchs within one second
#define NCCL_SEARCH_GLOBAL_TIMEOUT (3ULL<<19)
#define NCCL_SEARCH_TIMEOUT (1<<18)
#define NCCL_SEARCH_TIMEOUT_TREE (1<<17)
#define NCCL_SEARCH_TIMEOUT_SAMECHANNELS (1<<10)
#define FORCED_ORDER_PCI 1
#define FORCED_ORDER_REPLAY 2
ncclResult_t ncclTopoReplayGetGpu(struct ncclTopoSystem* system, struct ncclTopoGraph* graph, int step, int* g) {
*g = -1;
if (graph->nChannels == 0) return ncclInternalError;
int ngpus = system->nodes[GPU].count;
int nextRank = graph->intra[(graph->nChannels-1)*ngpus+step+1];
for (int i=0; i<ngpus; i++) if (system->nodes[GPU].nodes[i].gpu.rank == nextRank) {
*g = i;
return ncclSuccess;
}
if (*g == -1) return ncclInternalError;
return ncclSuccess;
}
ncclResult_t ncclTopoSearchRecGpu(struct ncclTopoSystem* system, struct ncclTopoGraph* graph, struct ncclTopoGraph* saveGraph, struct ncclTopoNode* gpu, int step, int backToNet, int backToFirstRank, int forcedOrder, int *time);
ncclResult_t ncclTopoSearchTryGpu(struct ncclTopoSystem* system, struct ncclTopoGraph* graph, struct ncclTopoGraph* saveGraph, int step, int backToNet, int backToFirstRank, int forcedOrder, int *time, int type, int index, int g) {
const uint64_t flag = 1ULL<<(graph->nChannels);
struct ncclTopoNode* gpu;
NCCLCHECK(ncclTopoFollowPath(system, graph, type, index, GPU, g, 1, &gpu));
if (gpu) {
gpu->used ^= flag;
NCCLCHECK(ncclTopoSearchRecGpu(system, graph, saveGraph, gpu, step, backToNet, backToFirstRank, forcedOrder, time));
gpu->used ^= flag;
NCCLCHECK(ncclTopoFollowPath(system, graph, type, index, GPU, g, -1, &gpu));
}
return ncclSuccess;
}
static int ncclTopoCountXGMI(struct ncclTopoSystem* system, struct ncclTopoGraph* graph) {
int ngpus = system->nodes[GPU].count;
int count = 0;
for (int c=0; c<graph->nChannels; c++) {
for (int i=0; i<ngpus; i++) {
int g = graph->intra[ngpus*c+i];
int n = graph->intra[ngpus*c+((i+1)%ngpus)];
struct ncclTopoNode *node;
int j;
for (j=0; j<ngpus; j++)
if (system->nodes[GPU].nodes[j].gpu.rank == g) break;
if (j<ngpus) {
node = system->nodes[GPU].nodes+j;
for (int k = 0; k<system->nodes[GPU].count; k++) {
if (node->paths[GPU][k].count == 1) {
struct ncclTopoLink* link = node->paths[GPU][k].list[0];
struct ncclTopoNode* remNode = link->remNode;
if (remNode->gpu.rank == n) {
if (link->type == LINK_NVL)
count ++;
}
}
}
}
}
}
return count;
}
ncclResult_t ncclTopoCompareGraphs(struct ncclTopoSystem* system, struct ncclTopoGraph* graph, struct ncclTopoGraph* refGraph, int* copy) {
// 1. Constraint to get the same nChannels between Rings and Trees
if (graph->nChannels < graph->minChannels) return ncclSuccess;
// 2. Try to get better bandwidth
if (graph->nChannels*graph->speedIntra < refGraph->nChannels*refGraph->speedIntra) return ncclSuccess;
if (graph->nChannels*graph->speedIntra > refGraph->nChannels*refGraph->speedIntra) {
*copy = 1;
return ncclSuccess;
}
// 3. Less hops (but not at the price of going cross NICs)
if (graph->crossNic == refGraph->crossNic && graph->nHops < refGraph->nHops) *copy = 1;
// 4. Prefer graph with more XGMI connections
if (graph->nChannels == refGraph->nChannels
&& ncclTopoCountXGMI(system, refGraph) < ncclTopoCountXGMI(system, graph)) *copy = 1;
return ncclSuccess;
}
ncclResult_t ncclTopoSearchRecGpu(struct ncclTopoSystem* system, struct ncclTopoGraph* graph, struct ncclTopoGraph* saveGraph, struct ncclTopoNode* gpu, int step, int backToNet, int backToFirstRank, int forcedOrder, int *time) {
if ((*time) <= 0) return ncclSuccess;
(*time)--;
int ngpus = system->nodes[GPU].count;
if (step == ngpus) {
// Determine whether we found a better solution or not
int copy = 0;
graph->nChannels++;
NCCLCHECK(ncclTopoCompareGraphs(system, graph, saveGraph, &copy));
if (copy) {
memcpy(saveGraph, graph, sizeof(struct ncclTopoGraph));
if (graph->nChannels == graph->maxChannels) *time = -1;
}
if (graph->nChannels < graph->maxChannels) {
NCCLCHECK(ncclTopoSearchRec(system, graph, saveGraph, time));
}
graph->nChannels--;
return ncclSuccess;
}
graph->intra[graph->nChannels*ngpus+step] = gpu->gpu.rank;
int g = gpu - system->nodes[GPU].nodes;
if (step == backToNet) {
// first get back to NIC
if (system->nodes[NET].count) {
int startNetIndex;
NCCLCHECK(getNetIndex(system, graph->inter[graph->nChannels*2], &startNetIndex));
struct ncclTopoNode* startNet = system->nodes[NET].nodes+startNetIndex;
for (int n=0; n<system->nodes[NET].count; n++) {
struct ncclTopoNode* net = system->nodes[NET].nodes+n;
if (graph->pattern == NCCL_TOPO_PATTERN_TREE && net->id != startNet->id) continue; // Trees are symmetric
if (graph->crossNic != 1 && (net->net.asic != startNet->net.asic || net->net.port != startNet->net.port)) continue;
NCCLCHECK(ncclTopoFollowPath(system, graph, GPU, g, NET, n, 1, &net));
if (net) {
graph->inter[graph->nChannels*2+1] = net->id;
NCCLCHECK(ncclTopoSearchRecGpu(system, graph, saveGraph, gpu, step, -1, backToFirstRank, forcedOrder, time));
NCCLCHECK(ncclTopoFollowPath(system, graph, GPU, g, NET, n, -1, &net));
}
}
}
} else if (step < system->nodes[GPU].count-1) {
// Go to next GPU
int next[NCCL_TOPO_MAX_NODES];
int count;
if (forcedOrder == FORCED_ORDER_PCI) { // Try the PCI order
next[0] = step+1;
count = 1;
} else if (forcedOrder == FORCED_ORDER_REPLAY) { // Try last channel order
NCCLCHECK(ncclTopoReplayGetGpu(system, graph, step, next));
count = 1;
} else { // Normal search
NCCLCHECK(ncclTopoSearchNextGpuSort(system, graph, gpu, next, &count, backToNet == -1 ? 0 : backToNet == step+1 ? 1 : -1 ));
}
for (int i=0; i<count; i++) {
NCCLCHECK(ncclTopoSearchTryGpu(system, graph, saveGraph, step+1, backToNet, backToFirstRank, forcedOrder, time, GPU, g, next[i]));
}
} else if (step == backToFirstRank) {
// Find first GPU and loop back to it
int p;
NCCLCHECK(getGpuIndex(system, graph->intra[graph->nChannels*ngpus], &p));
struct ncclTopoNode* firstGpu;
NCCLCHECK(ncclTopoFollowPath(system, graph, GPU, g, GPU, p, 1, &firstGpu));
if (firstGpu) {
NCCLCHECK(ncclTopoSearchRecGpu(system, graph, saveGraph, firstGpu, step+1, backToNet, -1, forcedOrder, time));
NCCLCHECK(ncclTopoFollowPath(system, graph, GPU, g, GPU, p, -1, &firstGpu));
}
} else {
// Next path
NCCLCHECK(ncclTopoSearchRecGpu(system, graph, saveGraph, gpu, ngpus, -1, -1, forcedOrder, time));
}
return ncclSuccess;
}
ncclResult_t ncclTopoSearchRecNet(struct ncclTopoSystem* system, struct ncclTopoGraph* graph, struct ncclTopoGraph* saveGraph, int backToNet, int backToFirstRank, int* time) {
const int speed = graph->speedInter;
for (int n=0; n<system->nodes[NET].count; n++) {
struct ncclTopoNode* net = system->nodes[NET].nodes+n;
struct ncclTopoNode* gpu;
if (graph->collNet && net->net.collSupport == 0) continue;
if (net->net.width < speed) continue;
if (net->net.maxChannels == 0) continue;
graph->inter[graph->nChannels*2] = net->id;
for (int i=0; i<system->nodes[NET].count; i++) {
if ((system->nodes[NET].nodes[i].net.asic == net->net.asic) &&
(system->nodes[NET].nodes[i].net.port == net->net.port)) {
system->nodes[NET].nodes[i].net.width -= speed;
}
}
net->net.maxChannels--;
// First try to replay the last channel
if (graph->nChannels > 0) {
int g;
NCCLCHECK(ncclTopoReplayGetGpu(system, graph, -1, &g));
NCCLCHECK(ncclTopoSearchTryGpu(system, graph, saveGraph, 0, backToNet, backToFirstRank, FORCED_ORDER_REPLAY, time, NET, n, g));
}
if (graph->nChannels == 0 || graph->sameChannels == 0) {
if (graph->nChannels == 0) {
// Always try the PCI order first to set a reference, but don't count in the timeout nor let it run for long
struct ncclTopoLinkList* paths = net->paths[GPU];
// find the first GPU that is closest to NIC
int f = 0;
for (int i = 0; i<system->nodes[GPU].count; i++)
if (paths[i].count < paths[f].count) f = i;
int t = 1 << 10;
NCCLCHECK(ncclTopoSearchTryGpu(system, graph, saveGraph, 0, backToNet, backToFirstRank, FORCED_ORDER_PCI, &t, NET, n, f));
if (t == -1) *time = -1;
}
// Then try the most local GPUs
float maxWidth = 0;
int minHops = 0xfffffff;
struct ncclTopoLinkList* paths = net->paths[GPU];
for (int g=0; g<system->nodes[GPU].count; g++) {
if (paths[g].width > maxWidth) {
maxWidth = paths[g].width;
minHops = paths[g].count;
} else if (paths[g].width == maxWidth && paths[g].count < minHops) {
minHops = paths[g].count;
}
}
if (maxWidth >= speed) {
// In the first loop, avoid using GPUs in both directions between channels (one channel
// sending from that GPU and one channel receiving to that GPU), since that usually leads
// to lower BW.
for (int tryGpuBidir=0; tryGpuBidir<2; tryGpuBidir++) {
for (int g=0; g<system->nodes[GPU].count; g++) {
if (paths[g].width == maxWidth && paths[g].count == minHops) {
gpu = system->nodes[GPU].nodes+g;
int gpuUsed = gpuPciWidth(gpu) > 0 ? 0 : 1;
if (tryGpuBidir == gpuUsed) {
NCCLCHECK(ncclTopoSearchTryGpu(system, graph, saveGraph, 0, backToNet, backToFirstRank, 0, time, NET, n, g));
}
}
}
}
}
}
net->net.maxChannels++;
for (int i=0; i<system->nodes[NET].count; i++) {
if ((system->nodes[NET].nodes[i].net.asic == net->net.asic) &&
(system->nodes[NET].nodes[i].net.port == net->net.port)) {
system->nodes[NET].nodes[i].net.width += speed;
}
}
}
return ncclSuccess;
}
/* Search Patterns
*
* Intra-node
* Ring : GPU a -> GPU b -> .. -> GPU x -> GPU a
* (=Split Tree Loop)
* Tree : GPU a -> GPU b -> .. -> GPU x
* (=Split Tree)
*
* Inter-node
* Ring : NET n -> GPU a -> GPU b -> .. -> GPU x -> NET n (or m if crossNic)
* Tree : NET n -> GPU a -> GPU b -> .. -> GPU x
* `--> NET n (or m if crossNic)
* Split Tree : NET n -> GPU a -> GPU b -> .. -> GPU x
* `--> NET n (or m if crossNic)
* Split Tree Loop : NET n -> GPU a -> GPU b -> .. -> GPU x -> GPU a
* `--> NET n (or m if crossNic)
*/
ncclResult_t ncclTopoSearchParams(struct ncclTopoSystem* system, int pattern, int* backToNet, int* backToFirstRank) {
if (system->nodes[NET].count) {
if (pattern == NCCL_TOPO_PATTERN_RING) *backToNet = system->nodes[GPU].count-1;
else if (pattern == NCCL_TOPO_PATTERN_TREE) *backToNet = 0;
else *backToNet = 1;
if (pattern == NCCL_TOPO_PATTERN_SPLIT_TREE_LOOP) *backToFirstRank = system->nodes[GPU].count-1;
else *backToFirstRank = -1;
} else {
*backToNet = -1;
if (pattern == NCCL_TOPO_PATTERN_RING || pattern == NCCL_TOPO_PATTERN_SPLIT_TREE_LOOP) *backToFirstRank = system->nodes[GPU].count-1;
else *backToFirstRank = -1;
}
return ncclSuccess;
}
ncclResult_t ncclTopoSearchRec(struct ncclTopoSystem* system, struct ncclTopoGraph* graph, struct ncclTopoGraph* saveGraph, int* time) {
int backToNet, backToFirstRank;
NCCLCHECK(ncclTopoSearchParams(system, graph->pattern, &backToNet, &backToFirstRank));
if (system->nodes[NET].count) {
// Start from NET
ncclTopoSearchRecNet(system, graph, saveGraph, backToNet, backToFirstRank, time);
} else {
// Intra-node only.
if (graph->nChannels == 0) {
// Try PCI order first
NCCLCHECK(ncclTopoSearchTryGpu(system, graph, saveGraph, 0, backToNet, backToFirstRank, FORCED_ORDER_PCI, time, -1, -1, 0));
} else {
// Also try to replay previous channel
int g;
NCCLCHECK(ncclTopoReplayGetGpu(system, graph, -1, &g));
NCCLCHECK(ncclTopoSearchTryGpu(system, graph, saveGraph, 0, backToNet, backToFirstRank, FORCED_ORDER_REPLAY, time, -1, -1, g));
}
if (graph->sameChannels == 0 || graph->nChannels == 0) {
// Finally, try all other possibilities unless we are forced to use the same channels
for (int g=0; g<system->nodes[GPU].count; g++) {
NCCLCHECK(ncclTopoSearchTryGpu(system, graph, saveGraph, 0, backToNet, backToFirstRank, 0, time, -1, -1, g));
}
}
}
return ncclSuccess;
}
/************************************/
/* User defined graph from XML file */
/************************************/
struct kvDict kvDictLinkType[] = { { "SYS", PATH_SYS }, { "PHB", PATH_PHB }, { "PIX", PATH_PIX }, { "PXB", PATH_PXB }, { "NVL", PATH_NVL }, { "LOC", PATH_LOC }, { NULL, 0 } };
ncclResult_t ncclTopoGetChannelFromXml(struct ncclXmlNode *xmlChannel, int c, struct ncclTopoSystem* system, struct ncclTopoGraph* graph) {
int ngpus = system->nodes[GPU].count;
int* inter = graph->inter+2*c;
int* intra = graph->intra+ngpus*c;
int n=0, g=0;
for (int s=0; s<xmlChannel->nSubs; s++) {
struct ncclXmlNode* sub = xmlChannel->subs[s];
int dev;
NCCLCHECK(xmlGetAttrInt(sub, "dev", &dev));
if (strcmp(sub->name, "net") == 0) {
inter[n++] = dev;
} else if (strcmp(sub->name, "gpu") == 0) {
int rank = -1;
for (int g=0; g<ngpus; g++) {
if (system->nodes[GPU].nodes[g].gpu.dev == dev) rank = system->nodes[GPU].nodes[g].gpu.rank;
}
if (rank == -1) {
WARN("XML Import Channel : dev %d not found.", dev);
return ncclSystemError;
}
intra[g++] = rank;
}
}
return ncclSuccess;
}
ncclResult_t ncclTopoGetGraphFromXmlSub(struct ncclXmlNode *xmlGraph, struct ncclTopoSystem* system, struct ncclTopoGraph* graph, int* nChannels) {
int id;
NCCLCHECK(xmlGetAttrInt(xmlGraph, "id", &id));
if (graph->id != id) return ncclSuccess;
int crossNic;
NCCLCHECK(xmlGetAttrInt(xmlGraph, "crossnic", &crossNic));
if (graph->crossNic == 0 && crossNic == 1) return ncclSuccess;
graph->crossNic = crossNic;
NCCLCHECK(xmlGetAttrInt(xmlGraph, "pattern", &graph->pattern));
NCCLCHECK(xmlGetAttrInt(xmlGraph, "nchannels", &graph->nChannels));
NCCLCHECK(xmlGetAttrFloat(xmlGraph, "speedintra", &graph->speedIntra));
NCCLCHECK(xmlGetAttrFloat(xmlGraph, "speedinter", &graph->speedInter));
const char* str;
NCCLCHECK(xmlGetAttr(xmlGraph, "typeintra", &str));
NCCLCHECK(kvConvertToInt(str, &graph->typeIntra, kvDictLinkType));
NCCLCHECK(xmlGetAttr(xmlGraph, "typeinter", &str));
NCCLCHECK(kvConvertToInt(str, &graph->typeInter, kvDictLinkType));
NCCLCHECK(xmlGetAttrInt(xmlGraph, "samechannels", &graph->sameChannels));
for (int s=0; s<xmlGraph->nSubs; s++) {
NCCLCHECK(ncclTopoGetChannelFromXml(xmlGraph->subs[s], s, system, graph));
}
*nChannels = xmlGraph->nSubs;
return ncclSuccess;
}
ncclResult_t ncclTopoGetGraphFromXml(struct ncclXmlNode *xmlGraphs, struct ncclTopoSystem* system, struct ncclTopoGraph* graph, int* nChannels) {
for (int s=0; s<xmlGraphs->nSubs; s++) {
NCCLCHECK(ncclTopoGetGraphFromXmlSub(xmlGraphs->subs[s], system, graph, nChannels));
}
return ncclSuccess;
}
/* And the reverse : graph->xml */
ncclResult_t ncclTopoGetXmlFromChannel(struct ncclTopoGraph* graph, int c, struct ncclTopoSystem* system, struct ncclXml *xml, struct ncclXmlNode* parent) {
struct ncclXmlNode* xmlChannel;
int ngpus = system->nodes[GPU].count;
int* inter = graph->inter+2*c;
int* intra = graph->intra+ngpus*c;
NCCLCHECK(xmlAddNode(xml, parent, "channel", &xmlChannel));
struct ncclXmlNode* node;
if (system->nodes[NET].count) {
NCCLCHECK(xmlAddNode(xml, xmlChannel, "net", &node));
NCCLCHECK(xmlSetAttrInt(node, "dev", inter[0]));
}
for (int g=0; g<ngpus; g++) {
NCCLCHECK(xmlAddNode(xml, xmlChannel, "gpu", &node));
int dev = -1;
for (int i=0; i<ngpus; i++) {
if (system->nodes[GPU].nodes[i].gpu.rank == intra[g]) dev = system->nodes[GPU].nodes[i].gpu.dev;
}
if (dev == -1) {
WARN("XML Export Channel : rank %d not found.", intra[g]);
return ncclInternalError;
}
NCCLCHECK(xmlSetAttrInt(node, "dev", dev));
}
if (system->nodes[NET].count) {
NCCLCHECK(xmlAddNode(xml, xmlChannel, "net", &node));
NCCLCHECK(xmlSetAttrInt(node, "dev", inter[1]));
}
return ncclSuccess;
}
ncclResult_t ncclTopoGetXmlFromGraph(struct ncclTopoGraph* graph, struct ncclTopoSystem* system, struct ncclXml *xml, struct ncclXmlNode* parent) {
struct ncclXmlNode* xmlGraph;
NCCLCHECK(xmlAddNode(xml, parent, "graph", &xmlGraph));
NCCLCHECK(xmlSetAttrInt(xmlGraph, "id", graph->id));
NCCLCHECK(xmlSetAttrInt(xmlGraph, "pattern", graph->pattern));
NCCLCHECK(xmlSetAttrInt(xmlGraph, "crossnic", graph->crossNic));
NCCLCHECK(xmlSetAttrInt(xmlGraph, "nchannels", graph->nChannels));
NCCLCHECK(xmlSetAttrFloat(xmlGraph, "speedintra", graph->speedIntra));
NCCLCHECK(xmlSetAttrFloat(xmlGraph, "speedinter", graph->speedInter));
const char* str;
NCCLCHECK(kvConvertToStr(graph->typeIntra, &str, kvDictLinkType));
NCCLCHECK(xmlSetAttr(xmlGraph, "typeintra", str));
NCCLCHECK(kvConvertToStr(graph->typeInter, &str, kvDictLinkType));
NCCLCHECK(xmlSetAttr(xmlGraph, "typeinter", str));
NCCLCHECK(xmlSetAttrInt(xmlGraph, "samechannels", graph->sameChannels));
for (int c=0; c<graph->nChannels; c++) {
NCCLCHECK(ncclTopoGetXmlFromChannel(graph, c, system, xml, xmlGraph));
}
return ncclSuccess;
}
ncclResult_t ncclTopoGetXmlFromGraphs(int ngraphs, struct ncclTopoGraph** graphs, struct ncclTopoSystem* system, struct ncclXml *xml) {
xml->maxIndex = 0;
struct ncclXmlNode* xmlGraphs;
NCCLCHECK(xmlAddNode(xml, NULL, "graphs", &xmlGraphs));
NCCLCHECK(xmlSetAttrInt(xmlGraphs, "version", NCCL_GRAPH_XML_VERSION));
for (int g=0; g<ngraphs; g++) {
NCCLCHECK(ncclTopoGetXmlFromGraph(graphs[g], system, xml, xmlGraphs));
}
return ncclSuccess;
}
/* Parse user defined rings. Format is like :
* "0 1|1 0|0 1 2 3|3 2 1 0|0 2 3 1|1 3 2 0|0 1 2 3 4 5 6 7|7 6 5 4 3 2 1 0"
* Rings with a non-matching number of ranks are ignored so we can provide
* rings for multiple cases.
*/
#define MAX_ENV_RANKS 512
static ncclResult_t parseGraph(const char* str, int* nChannelsRet, int ngpus, int* channels) {
int ranks[MAX_ENV_RANKS];
int nChannels = 0;
int rank = 0;
int offset = 0;
int status = 0; // 0 : between numbers, 1 : inside number
do {
int digit = str[offset] - '0';
if (digit >= 0 && digit <= 9) {
if (status == 0) {
ranks[rank] = digit;
status = 1;
} else {
ranks[rank] = ranks[rank]*10+digit;
}
} else {
if (status == 1) {
rank++;
if (rank == MAX_ENV_RANKS) goto end;
}
status = 0;
if (str[offset] == '|' || str[offset] == '\0') {
// Ignore if ngpus doesn't match
if (rank != ngpus) goto newchannel;
for (int r=0; r<ngpus; r++) {
int rank = ranks[r];
// Ignore if ranks are out of bounds
if (rank < 0 || rank >= ngpus) goto newchannel;
// Ignore if ranks are duplicate
for (int i=0; i<r; i++)
if (ranks[i] == rank) goto newchannel;
channels[nChannels*ngpus+r] = rank;
}
nChannels++;
newchannel:
rank = 0;
}
}
} while (str[offset++] != 0);
end:
*nChannelsRet = nChannels;
return ncclSuccess;
}
static void parseChordalRing(struct ncclTopoSystem* system, char **str) {
static const char *ringBase = "0 6 7 4 5 3 2 1|0 5 6 3 7 1 4 2|0 4 6 2 7 5 1 3|0 1 2 3 5 4 7 6|0 2 4 1 7 3 6 5|0 3 1 5 7 2 6 4";
static char ringRemap[256];
int id[8], dist[8];
int i;
int ngpus = system->nodes[GPU].count;
// single node CR8G only
if (ngpus != 8 || system->nodes[NET].count != 0)
return;
// validate chordal ring and calculate distance
for (i=0; i<ngpus; i++) {
struct ncclTopoNode* node = system->nodes[GPU].nodes+i;
if (node->paths[GPU] == NULL) continue;
int sum = ngpus*(ngpus-1)/2 - node->gpu.rank;
int count = 0;
for (int n = 0; n<ngpus; n++) {
struct ncclTopoLink* link;
for (link = node->links; link->remNode; link++) {
if (link->remNode->gpu.rank == n) break;
}
if (!link->remNode) continue;
if (link->type != LINK_NVL) continue;
sum -= system->nodes[GPU].nodes[n].gpu.rank;
count ++;
}
if(count != ngpus-2 || sum < 0 || sum > ngpus-1) {
return;
}
dist[i] = sum;
}
// remap GPU ids
for (i = 0; i<ngpus; i++) id[i] = i;
for (i = 0; i<ngpus; i++) {
if (dist[i] == ngpus-1-i) continue;
int j, m, n, temp;
for (j=i+1; j < ngpus; j++)
if(dist[j] == ngpus-1-i) break;
m = dist[i]; n = dist[j]; dist[i] = n; dist[j] = m;
temp = id[m]; id[m] = id[n]; id[n] = temp; temp =dist[m];
dist[m] = dist[n]; dist[n] = temp;
}
// create chordal ring based on reference and remapped ids
for (i = 0; i <strlen(ringBase); i++) {
if (ringBase[i] >= '0' && ringBase[i] <= '9')
ringRemap[i] = id[ringBase[i]-'0']+'0';
else
ringRemap[i] = ringBase[i];
}
ringRemap[i] = 0;
*str = ringRemap;
INFO(NCCL_GRAPH, "Use chordal ring: %s", ringRemap);
return;
}
#if defined(__HIP_PLATFORM_HCC__) || defined(__HCC__) || defined(__HIPCC__)
float speedArray[] = { 24.0, 20.0, 18.0, 15.0, 12.0, 10.0, 9.0, 7.0, 6.0, 5.0, 4.0, 3.0, 2.4, 1.2, 0.24, 0.12 };
#else
float speedArray[] = { 42.0, 24.0, 21.0, 18.0, 15.0, 12.0, 10.0, 9.0, 7.0, 6.0, 5.0, 4.0, 3.0, 2.4, 1.2, 0.24, 0.12 };
#endif
#define NSPEEDS (sizeof(speedArray)/sizeof(float))
ncclResult_t ncclTopoCompute(ncclTopoSystem* system, struct ncclTopoGraph* graph) {
int ngpus = system->nodes[GPU].count;
int crossNic = (system->nodes[NET].count > 1) && graph->crossNic ? 1 : 0;
graph->speedIntra = graph->speedInter = 0;
if (graph->crossNic == 2) graph->crossNic = 0;
graph->typeIntra = ngpus == 1 ? PATH_LOC : PATH_NVL;
graph->typeInter = PATH_PIX;
graph->nChannels = 0;
graph->sameChannels = 1;
char* str = getenv("NCCL_GRAPH_FILE");
if (str) {
INFO(NCCL_ENV, "NCCL_GRAPH_FILE set by environment to %s", str);
struct ncclXml* xml;
NCCLCHECK(ncclCalloc(&xml, 1));
NCCLCHECK(ncclTopoGetXmlGraphFromFile(str, xml));
int nChannels;
NCCLCHECK(ncclTopoGetGraphFromXml(xml->nodes, system, graph, &nChannels));
INFO(NCCL_GRAPH, "Search %d : %d channels loaded from XML graph", graph->id, nChannels);
free(xml);
if (graph->nChannels > 0) return ncclSuccess;
}
if (!str) parseChordalRing(system, &str);
if (str) {
NCCLCHECK(parseGraph(str, &graph->nChannels, ngpus, graph->intra));
for (int i=0; i<graph->nChannels*ngpus; i++) {
// Translate gpu numbers into ranks
graph->intra[i] = system->nodes[GPU].nodes[graph->intra[i]].gpu.rank;
}
// TODO : let user specify NICs
graph->inter[0] = graph->inter[1] = 0;
graph->speedIntra = graph->speedInter = system->maxWidth;
if (graph->pattern == NCCL_TOPO_PATTERN_RING) {
// Reverse the loop
for (int c=0; c<graph->nChannels; c++) {
for (int i=0; i<=ngpus/2; i++) {
int tmp = graph->intra[ngpus*c+i];
graph->intra[ngpus*c+i] = graph->intra[ngpus*c+(ngpus-i)%ngpus];
graph->intra[ngpus*c+ngpus-i] = tmp;
}
}
}
if (graph->nChannels) return ncclSuccess;
}
if (ngpus == 1) if (graph->pattern != NCCL_TOPO_PATTERN_RING) graph->pattern = NCCL_TOPO_PATTERN_TREE;
struct ncclTopoGraph tmpGraph;
memcpy(&tmpGraph, graph, sizeof(struct ncclTopoGraph));
// First try crossnic, then decrease speed and finally increase speedIntra.
tmpGraph.pattern = graph->pattern;
int pass = 1;
int speedIndex = 0;
while (speedArray[speedIndex] > system->maxWidth && speedIndex < NSPEEDS-1) speedIndex++;
tmpGraph.speedIntra = tmpGraph.speedInter = speedArray[speedIndex];
int64_t globalTimeout = NCCL_SEARCH_GLOBAL_TIMEOUT;
search:
int time = tmpGraph.sameChannels ? NCCL_SEARCH_TIMEOUT_SAMECHANNELS :
tmpGraph.pattern == NCCL_TOPO_PATTERN_TREE ? NCCL_SEARCH_TIMEOUT_TREE : NCCL_SEARCH_TIMEOUT;
tmpGraph.nChannels = 0;
globalTimeout -= time;
NCCLCHECK(ncclTopoSearchRec(system, &tmpGraph, graph, &time));
#if 0
printf("Pattern %d, crossNic %d, Speed %g/%g, type %d/%d, channels %d-%d sameChannels %d -> nChannels %dx%g/%g %s\n", tmpGraph.pattern, tmpGraph.crossNic, tmpGraph.speedInter, tmpGraph.speedIntra, tmpGraph.typeInter, tmpGraph.typeIntra, tmpGraph.minChannels, tmpGraph.maxChannels, tmpGraph.sameChannels, graph->nChannels, graph->speedInter, graph->speedIntra, time == 0 ? "TIMEOUT" : "");
for (int c=0; c<graph->nChannels; c++) {
printf("%2d : ", c);
for (int g=0; g<ngpus; g++) {
printf("%d ", graph->intra[c*ngpus+g]);
}
printf("\n");
}
#endif
// Optimal solution, stop here
if (graph->nChannels == graph->maxChannels && graph->speedInter == system->maxWidth) goto done;
if (pass == 1) {
// First pass, we don't have a solution yet ; try other options
// Try having different channels
if (tmpGraph.sameChannels == 1) {
tmpGraph.sameChannels = 0;
goto search;
}
tmpGraph.sameChannels = 1;
if (time != -1) globalTimeout += time;
else globalTimeout = NCCL_SEARCH_GLOBAL_TIMEOUT;
if (globalTimeout < 0) goto done;
int maxTypeIntra = system->nodes[NET].count > 0 ? tmpGraph.typeInter : PATH_SYS;
if (tmpGraph.typeIntra < maxTypeIntra && (graph->nChannels == 0 || tmpGraph.typeIntra < graph->typeIntra)) {
tmpGraph.typeIntra += 1;
goto search;
}
tmpGraph.typeIntra = ngpus == 1 ? PATH_LOC : PATH_NVL;
if (system->nodes[NET].count > 0 && tmpGraph.typeInter < PATH_SYS && (graph->nChannels == 0 || tmpGraph.typeInter < graph->typeInter || tmpGraph.typeInter < PATH_PXB)) {
tmpGraph.typeInter += 1;
goto search;
}
tmpGraph.typeInter = PATH_PIX;
// Try a simpler tree
if (tmpGraph.pattern == NCCL_TOPO_PATTERN_SPLIT_TREE_LOOP) {
tmpGraph.pattern = NCCL_TOPO_PATTERN_SPLIT_TREE;
goto search;
}
if (tmpGraph.pattern == NCCL_TOPO_PATTERN_SPLIT_TREE) {
tmpGraph.pattern = NCCL_TOPO_PATTERN_TREE;
goto search;
}
tmpGraph.pattern = graph->pattern;
if (crossNic && tmpGraph.crossNic == 0) {
// Try again with crossNic if permitted
tmpGraph.crossNic = crossNic;
goto search;
}
tmpGraph.crossNic = 0;
// Decrease speed until we find a solution
if ((speedIndex < NSPEEDS-1) && (graph->nChannels == 0 || (speedArray[speedIndex+1]/graph->speedInter > .49))) {
tmpGraph.speedInter = tmpGraph.speedIntra = speedArray[++speedIndex];
goto search;
}
speedIndex = 0;
while (speedArray[speedIndex] > system->maxWidth && speedIndex < NSPEEDS-1) speedIndex++;
tmpGraph.speedIntra = tmpGraph.speedInter = speedArray[speedIndex];
}
done:
// We have a solution. Start from that solution and move to pass 2.
if (pass == 1) {
time = -1;
memcpy(&tmpGraph, graph, sizeof(tmpGraph));
speedIndex = 0;
while (speedArray[speedIndex] > graph->speedInter && speedIndex < NSPEEDS-1) speedIndex++;
tmpGraph.speedIntra = tmpGraph.speedInter = speedArray[speedIndex];
tmpGraph.minChannels = graph->nChannels;
pass = 2;
}
// 3. See if we can increase speedIntra for trees (2 nodes or collnet)
if (pass == 2) {
if (time != 0 && graph->pattern != NCCL_TOPO_PATTERN_RING &&
tmpGraph.speedIntra == graph->speedIntra && tmpGraph.speedIntra < tmpGraph.speedInter*2 &&
speedIndex > 0) {
tmpGraph.speedIntra = speedArray[--speedIndex];
goto search;
}
time = -1;
memcpy(&tmpGraph, graph, sizeof(tmpGraph));
}
if (graph->nChannels == 0 && graph->collNet == 0) {
WARN("Could not find a path for pattern %d, falling back to simple order\n", graph->pattern);
for (int i=0; i<ngpus; i++) graph->intra[i] = system->nodes[GPU].nodes[i].gpu.rank;
graph->inter[0] = graph->inter[1] = 0;
graph->speedIntra = graph->speedInter = 0.1;
graph->typeIntra = graph->typeInter = PATH_SYS;
graph->nChannels = 1;
}
if (graph->speedIntra >= 25.0) {
int dupChannels = std::min(graph->nChannels*2, graph->maxChannels);
memcpy(graph->intra+graph->nChannels*ngpus, graph->intra, (dupChannels-graph->nChannels)*ngpus*sizeof(int));
memcpy(graph->inter+graph->nChannels*2,graph->inter, (dupChannels-graph->nChannels)*2*sizeof(int));
graph->speedIntra /= DIVUP(dupChannels, graph->nChannels);
graph->speedInter /= DIVUP(dupChannels, graph->nChannels);
graph->nChannels = dupChannels;
}
return ncclSuccess;
}
ncclResult_t ncclTopoPrintGraph(struct ncclTopoSystem* system, struct ncclTopoGraph* graph) {
INFO(NCCL_GRAPH, "Pattern %d, crossNic %d, nChannels %d, speed %f/%f, type %s/%s, sameChannels %d", graph->pattern, graph->crossNic, graph->nChannels, graph->speedIntra, graph->speedInter, topoPathTypeStr[graph->typeIntra], topoPathTypeStr[graph->typeInter], graph->sameChannels);
int ngpus = system->nodes[GPU].count;
char line[1024];
for (int c=0; c<graph->nChannels; c++) {
sprintf(line, "%2d :", c);
int offset = strlen(line);
if (system->nodes[NET].count > 0) {
sprintf(line+offset, " %s/%d", topoNodeTypeStr[NET], graph->inter[2*c]);
offset = strlen(line);
}
for (int i=0; i<ngpus; i++) {
sprintf(line+offset, " %s/%d", topoNodeTypeStr[GPU], graph->intra[ngpus*c+i]);
offset = strlen(line);
}
if (system->nodes[NET].count > 0) {
sprintf(line+offset, " %s/%d", topoNodeTypeStr[NET], graph->inter[2*c+1]);
offset = strlen(line);
}
INFO(NCCL_GRAPH, "%s", line);
}
return ncclSuccess;
}
ncclResult_t ncclTopoDumpGraphs(struct ncclTopoSystem* system, int ngraphs, struct ncclTopoGraph** graphs) {
char* str = getenv("NCCL_GRAPH_DUMP_FILE");
if (str) {
INFO(NCCL_ENV, "NCCL_GRAPH_DUMP_FILE set by environment to %s", str);
struct ncclXml* xml;
NCCLCHECK(ncclCalloc(&xml, 1));
NCCLCHECK(ncclTopoGetXmlFromGraphs(ngraphs, graphs, system, xml));
NCCLCHECK(ncclTopoDumpXmlToFile(str, xml));
free(xml);
}
return ncclSuccess;
}
ncclResult_t ncclTopoGetNetDev(struct ncclTopoSystem* system, int rank, struct ncclTopoGraph* graph, int channelId, int* dev) {
if (graph) {
// Honor the net device in the graph
int channel = channelId%graph->nChannels;
int ngpus = system->nodes[GPU].count;
int index = graph->intra[channel*ngpus] == rank ? 0 : 1;
*dev = graph->inter[channel*2+index];
} else {
int64_t id;
NCCLCHECK(ncclTopoGetLocalNet(system, rank, &id, channelId));
*dev = id;
}
return ncclSuccess;
}
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