disabling msccl for fp8 datatype (#1888)

* disabling msccl for fp8 datatype --------- Co-authored-by: Marzieh Berenjkoub <mberenjk@amd.com>
2025-09-11 13:09:34 -05:00
parent de9ebd8a8b
commit ada4e12360
1 changed files with 8 additions and 4 deletions
@@ -158,10 +158,14 @@ ncclResult_t ncclAllReduce_impl(const void* sendbuff, void* recvbuff, size_t cou
  }

  if (mscclAvailable(comm) && !mscclIsCaller()) {
-    if (datatype != ncclBfloat16 || (count * ncclTypeSize(datatype) <= 8388608)) {
-	return mscclEnqueueCheck(
-                sendbuff, nullptr, nullptr, recvbuff, nullptr, nullptr,
-                count, datatype, 0, 0, op, mscclFuncAllReduce, comm, stream);	
+    //MSCCL not supported for FP8 datatype
+    if (datatype != ncclFloat8e4m3 && datatype != ncclFloat8e5m2) {
+      // MSCCL threshold for Bfloat16 = 8MB
+      if (datatype != ncclBfloat16 || (count * ncclTypeSize(datatype) <= 8388608)) {
+        return mscclEnqueueCheck(
+                      sendbuff, nullptr, nullptr, recvbuff, nullptr, nullptr,
+                      count, datatype, 0, 0, op, mscclFuncAllReduce, comm, stream);
+      }
    }
  }