move to a2a api (#9)

src/alltoall.cu

@@ -60,23 +60,8 @@ void AlltoAllGetBw(size_t count, int typesize, double sec, double* algBw, double
 }
 
 testResult_t AlltoAllRunColl(void* sendbuff, void* recvbuff, size_t count, ncclDataType_t type, ncclRedOp_t op, int root, ncclComm_t comm, hipStream_t stream) {
-  int nRanks;
+  NCCLCHECK(ncclAllToAll(sendbuff, recvbuff, count, type, comm, stream));
-  NCCLCHECK(ncclCommCount(comm, &nRanks));
-  size_t rankOffset = count * wordSize(type);
-  if (count == 0) return testSuccess;
-
-#if NCCL_MAJOR < 2 || NCCL_MINOR < 7
-  printf("NCCL 2.7 or later is needed for alltoall. This test was compiled with %d.%d.\n", NCCL_MAJOR, NCCL_MINOR);
-  return testNcclError;
-#else
-  NCCLCHECK(ncclGroupStart());
-  for (int r=0; r<nRanks; r++) {
-    NCCLCHECK(ncclSend(((char*)sendbuff)+r*rankOffset, count, type, r, comm, stream));
-    NCCLCHECK(ncclRecv(((char*)recvbuff)+r*rankOffset, count, type, r, comm, stream));
-  }
-  NCCLCHECK(ncclGroupEnd());
   return testSuccess;
-#endif
 }
 
 struct testColl alltoAllTest = {