rocm-systems/src/graph/topo.h

/*************************************************************************
 * Copyright (c) 2016-2019, NVIDIA CORPORATION. All rights reserved.
 *
 * See LICENSE.txt for license information
 ************************************************************************/

#ifndef NCCL_TOPO_H_
#define NCCL_TOPO_H_

#include "graph.h"
#include "core.h"

#define LOC_WIDTH 5000
#define PASCAL_NVLINK_WIDTH 18
#define VOLTA_NVLINK_WIDTH 21
#define PCI_WIDTH 12           // PCI Gen3 x16
#define QPI_WIDTH 8
#define SKL_QPI_WIDTH 12
#define P9_WIDTH 32
#define NET_WIDTH 12           // 100Gbit

// Intel CPU convert GPU P2P traffic into 64B PCI TLPs, to GPU
// to GPU traffic consumed more PCI bandwidth.
#define INTEL_P2P(speed) (speed*9/12)
#define INTEL_P2P_OVERHEAD(speed) (speed*12/9)

#define NCCL_TOPO_NODE_TYPES 6
#define GPU 0
#define PCI 1
#define NVS 2
#define CPU 3 // Actually NUMA domains
#define NIC 4
#define NET 5
extern const char* topoNodeTypeStr[];

#define LINK_LOC 0
#define LINK_NVL 1
#define LINK_PCI 2
#define LINK_QPI 3
#define LINK_NET 4
extern const char* topoLinkTypeStr[];

struct ncclTopoNode;
struct ncclTopoLink {
  int type;
  int width;
  struct ncclTopoNode* remNode;
};
#define NCCL_TOPO_MAX_LINKS 32
#define NCCL_TOPO_MAX_HOPS (NCCL_TOPO_MAX_NODES*NCCL_TOPO_NODE_TYPES)
#define SELECT_PATH 1
#define SELECT_LAST 2

#define NET_GDR_MASK 0x70000000

struct ncclTopoLinkList {
  struct ncclTopoLink* list[NCCL_TOPO_MAX_HOPS];
  int count;
  int width;
  int type;
};

struct ncclTopoNode {
  int type;
  int64_t id;
  int rank;
  int nlinks;
  struct ncclTopoLink links[NCCL_TOPO_MAX_LINKS];
  // Pre-computed paths to GPUs and NICs
  struct ncclTopoLinkList* paths[NCCL_TOPO_NODE_TYPES];
  // Used during search
  uint64_t used;
};

struct ncclTopoNodeSet {
  int count;
  struct ncclTopoNode nodes[NCCL_TOPO_MAX_NODES];
};

struct ncclTopoSystem {
  struct ncclTopoNodeSet nodes[NCCL_TOPO_NODE_TYPES];
  int maxSpeed;
  int maxWidth;
  int searchInitDone;
};

static ncclResult_t ncclTopoCreateNode(struct ncclTopoSystem* system, struct ncclTopoNode** node, int type, uint64_t id) {
  for (int i=0; i<system->nodes[type].count; i++) {
    if (system->nodes[type].nodes[i].id == id) {
      *node = system->nodes[type].nodes+i;
      return ncclSuccess;
    }
  }
  if (system->nodes[type].count == NCCL_TOPO_MAX_NODES) {
    WARN("Error : tried to create too many nodes of type %d\n", type);
    return ncclInternalError;
  }
  struct ncclTopoNode* n = system->nodes[type].nodes+system->nodes[type].count;
  system->nodes[type].count++;
  n->type = type;
  n->id = id;
  if (type == GPU) {
    // Create link to itself (used in some corner cases)
    n->nlinks=1;
    n->links[0].type = LINK_LOC;
    n->links[0].remNode = n;
    n->links[0].width = LOC_WIDTH;
  }
  *node = n;
  return ncclSuccess;
}

static ncclResult_t ncclTopoConnectNodes(struct ncclTopoNode* node, struct ncclTopoNode* remNode, int type, int width) {
  // Aggregate links into higher width for NVLink
  struct ncclTopoLink* link;
  for (link = node->links; link->remNode; link++) {
    if (link->remNode == remNode && link->type == type) break;
  }
  if (link->remNode == NULL) node->nlinks++;
  link->type = type;
  link->remNode = remNode;
  link->width += width;

  // Sort links in BW descending order
  struct ncclTopoLink linkSave;
  memcpy(&linkSave, link, sizeof(struct ncclTopoLink));
  while (link != node->links) {
    if ((link-1)->width >= linkSave.width) break;
    memcpy(link, link-1, sizeof(struct ncclTopoLink));
    link--;
  }
  memcpy(link, &linkSave, sizeof(struct ncclTopoLink));
  return ncclSuccess;
}

ncclResult_t ncclTopoPrintPaths(struct ncclTopoSystem* system);

#endif