From 6b2d7de200418c2fb01f013e16f64953d4be34af Mon Sep 17 00:00:00 2001
From: Wenkai Du <wenkai.du@amd.com>
Date: Thu, 30 Jan 2020 17:16:43 +0000
Subject: [PATCH] Add ring bandwidth correction factor

[ROCm/rccl commit: d1dae2721d028710c645ee9bdee6eee526234c6e]
---
 projects/rccl/src/enqueue.cc | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/projects/rccl/src/enqueue.cc b/projects/rccl/src/enqueue.cc
index e501300fcc..9ac1832e3d 100644
--- a/projects/rccl/src/enqueue.cc
+++ b/projects/rccl/src/enqueue.cc
@@ -235,6 +235,12 @@ static float treeCorrectionFactor[NCCL_NUM_PROTOCOLS][22] = {
   {  1.0,  1.0,  1.0,  1.0,  1.0,  1.0,  .41,  .27,  .25,  .39,  .46,  .72,  .76,  .87,  .92,  .97,  1.0,  1.0 ,  1.0 ,  1.0 ,  1.0 ,  1.0 }
 };
 
+static float ringCorrectionFactor[NCCL_NUM_PROTOCOLS][22] = {
+  {  1.0,  1.0,  1.0,  1.0,  1.0,  1.0,  .25,  .41,  .55,  .56,  .78,  .94,  1.0,  1.0,  1.0,  1.0,  1.0,  1.0 ,  1.0 ,  1.0 ,  1.0 ,  1.0 },
+  {  1.0,  1.0,  1.0,  1.0,  1.0,  1.0,  .25,  .41,  .55,  .56,  .78,  .94,  1.0,  1.0,  1.0,  1.0,  1.0,  1.0 ,  1.0 ,  1.0 ,  1.0 ,  1.0 },
+  {  1.0,  1.0,  1.0,  1.0,  1.0,  1.0,  .04,  .08,  .09,  .09,  .11,  .13,  .25,  .40,  .59,  .76,  .86,  1.0 ,  1.0 ,  1.0 ,  1.0 ,  1.0 }
+};
+
 static ncclResult_t getAlgoInfo(struct ncclInfo* info) {
   struct ncclComm* comm = info->comm;
   float minTime = 3600000.0; // Hopefully no operation will take an hour to complete.
@@ -247,6 +253,7 @@ static ncclResult_t getAlgoInfo(struct ncclInfo* info) {
       if (bw == 0) continue;
       int logSize = log2i(info->nBytes>>6);
       if (a == NCCL_ALGO_TREE && logSize < 22) bw *= treeCorrectionFactor[p][logSize];
+      else if (a == NCCL_ALGO_RING && logSize < 22) bw *= ringCorrectionFactor[p][logSize];
       float time = comm->latencies[info->coll][a][p] + (info->nBytes) / (1000 * bw);
       if (time < minTime) {
         info->algorithm = a;