Merge remote-tracking branch 'nccl/master' into develop

src/graph/paths.cc

@@ -11,6 +11,8 @@
 #include "comm.h"
 #include "net.h"
 #include "channel.h"
+#include "transport.h"
+#include "device.h"
 #include "xml.h"
 
 // Pre-compute GPU->NIC, GPU->GPU and NIC->GPU paths
@@ -868,12 +870,7 @@ static ncclResult_t ncclTopoGetNchannels(struct ncclComm* comm, int g /*local gp
 
 NCCL_PARAM(MinP2pNChannels, "MIN_P2P_NCHANNELS", 1);
 NCCL_PARAM(MaxP2pNChannels, "MAX_P2P_NCHANNELS", MAXCHANNELS);
-
-static int nextPow2(int v) {
-  int pow2 = 1;
-  while (pow2 < v) pow2 <<= 1;
-  return pow2;
-}
+extern int64_t ncclParamWorkArgsBytes();
 
 ncclResult_t ncclTopoComputeP2pChannels(struct ncclComm* comm) {
   /* here we already honor comm->max/minCTAs for p2pnChannels. */
@@ -904,24 +901,18 @@ ncclResult_t ncclTopoComputeP2pChannels(struct ncclComm* comm) {
   } else if (comm->topo->nodes[GPU].count == comm->topo->nRanks && (comm->topo->type & RCCL_TOPO_4P2H_ROME) && !(comm->topo->type & RCCL_TOPO_GDR_ALL) && !(comm->topo->type & RCCL_TOPO_XGMI_ALL)) {
     // Adjust P2P channels on Rome
     comm->p2pnChannelsPerPeer = 2;
-    comm->p2pnChannels = 2;
+    comm->p2pnChannels = std::min(pow2Up(comm->p2pnChannels), pow2Down(ncclDevMaxChannelsForArgsBytes(ncclParamWorkArgsBytes())));
   } else {
     // Round to next pow2 nChannelsPerPeer and nChannels
-    comm->p2pnChannelsPerPeer = (ncclParamNChannelsPerPeer() == -2 ? nextPow2(minChannels) : ncclParamNChannelsPerPeer());
+    comm->p2pnChannelsPerPeer = (ncclParamNChannelsPerPeer() == -2 ? pow2Up(minChannels) : ncclParamNChannelsPerPeer());
     // Doubling P2P channels per peer on single node
     if (comm->topo->nodes[GPU].count == comm->topo->nRanks && IsArchMatch(comm->topo->nodes[GPU].nodes[0].gpu.gcn, "gfx94")) comm->p2pnChannelsPerPeer *= 2;
-    comm->p2pnChannels = std::min(nextPow2(comm->p2pnChannels), 4*CHANNEL_LIMIT);
+    comm->p2pnChannels = std::min(pow2Up(comm->p2pnChannels), 4*CHANNEL_LIMIT);
   }
 
   // Init channels that weren't used so far
   for (int c=comm->nChannels; c<std::max(comm->nChannels, comm->p2pnChannels); c++) NCCLCHECK(initChannel(comm, c));
 
-  // We want to spread channels used when there aren't many and progressively
-  // fill the whole space of nChannels. To do so we mirror the bits in the
-  // nChannels space.
-  for (int c=0; c<comm->p2pnChannels; c++) {
-      comm->p2pChannels[c] = mirrorBits(c, comm->p2pnChannels);
-  }
   return ncclSuccess;
 }