From c90cfb8b0cc86da991783fed18e77d56355e31b4 Mon Sep 17 00:00:00 2001 From: Alex Duforest Date: Wed, 28 Oct 2026 11:24:13 -0700 Subject: [PATCH 1/3] perf(rccl): gfx950 tuner rows for 1-node Broadcast and Reduce Six rows for 1 node x 8 GPUs, Broadcast and Reduce: Ring/LL with 112 channels for [512K, 2M) and Ring/LL with RCCL's channel choice for [2M, 8M). The previous choice there, Ring/Simple, runs 1.5x to 3x slower. All other rows are unchanged. Co-Authored-By: Claude --- projects/rccl/CHANGELOG.md | 1 + projects/rccl/tuner/rccl_tuner_gfx950.csv | 6 ++++++ 2 files changed, 7 insertions(+) diff --git a/projects/rccl/CHANGELOG.md b/projects/rccl/CHANGELOG.md index 19c171208010..e837a0efd603 100644 --- a/projects/rccl/CHANGELOG.md +++ b/projects/rccl/CHANGELOG.md @@ -7,6 +7,7 @@ Full documentation for RCCL is available at [https://rccl.readthedocs.io](https: ### Added ### Changed +* gfx950 tuner table: Broadcast and Reduce on 1 node x 8 GPUs from 512 KiB to 8 MiB now run Ring/LL (112 channels below 2 MiB), 1.5x to 3x faster than the previous Ring/Simple choice. ### Removed diff --git a/projects/rccl/tuner/rccl_tuner_gfx950.csv b/projects/rccl/tuner/rccl_tuner_gfx950.csv index cb9c8ce54ea4..ceac3e9bd6a9 100644 --- a/projects/rccl/tuner/rccl_tuner_gfx950.csv +++ b/projects/rccl/tuner/rccl_tuner_gfx950.csv @@ -5,3 +5,9 @@ allreduce,1048576,2097000,ring,ll,56,1,8,-1,-1 allreduce,33554432,54525951,ring,ll128,64,2,16,-1,-1 allreduce,54525952,117440511,tree,simple,64,2,16,-1,-1 allreduce,117440512,234881024,ring,simple,48,2,16,-1,-1 +broadcast,524288,1048575,ring,ll,112,1,8,-1,-1 +broadcast,1048576,2097151,ring,ll,112,1,8,-1,-1 +broadcast,2097152,8388607,ring,ll,-1,1,8,-1,-1 +reduce,524288,1048575,ring,ll,112,1,8,-1,-1 +reduce,1048576,2097151,ring,ll,112,1,8,-1,-1 +reduce,2097152,8388607,ring,ll,-1,1,8,-1,-1 From f17e27707f9fee080654f616179c901ab811183c Mon Sep 17 00:00:00 2001 From: Alex Duforest Date: Wed, 28 Oct 2026 13:50:09 -0700 Subject: [PATCH 2/3] perf(rccl): merge the identical 112-channel rows Broadcast and Reduce [512K, 1M) and [1M, 2M) had the same Ring/LL/112 choice; one row each covers [512K, 2M). Lookups are unchanged at every size. Co-Authored-By: Claude --- projects/rccl/tuner/rccl_tuner_gfx950.csv | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/projects/rccl/tuner/rccl_tuner_gfx950.csv b/projects/rccl/tuner/rccl_tuner_gfx950.csv index ceac3e9bd6a9..2b2cf8220e56 100644 --- a/projects/rccl/tuner/rccl_tuner_gfx950.csv +++ b/projects/rccl/tuner/rccl_tuner_gfx950.csv @@ -5,9 +5,7 @@ allreduce,1048576,2097000,ring,ll,56,1,8,-1,-1 allreduce,33554432,54525951,ring,ll128,64,2,16,-1,-1 allreduce,54525952,117440511,tree,simple,64,2,16,-1,-1 allreduce,117440512,234881024,ring,simple,48,2,16,-1,-1 -broadcast,524288,1048575,ring,ll,112,1,8,-1,-1 -broadcast,1048576,2097151,ring,ll,112,1,8,-1,-1 +broadcast,524288,2097151,ring,ll,112,1,8,-1,-1 broadcast,2097152,8388607,ring,ll,-1,1,8,-1,-1 -reduce,524288,1048575,ring,ll,112,1,8,-1,-1 -reduce,1048576,2097151,ring,ll,112,1,8,-1,-1 +reduce,524288,2097151,ring,ll,112,1,8,-1,-1 reduce,2097152,8388607,ring,ll,-1,1,8,-1,-1 From dd1f320ea069a153f6cc0eaecfd138c07a6968dc Mon Sep 17 00:00:00 2001 From: Alex Duforest Date: Wed, 28 Oct 2026 15:41:14 -0700 Subject: [PATCH 3/3] perf(rccl): drop the CHANGELOG line Tuner-table-only changes don't carry a CHANGELOG entry. Co-Authored-By: Claude --- projects/rccl/CHANGELOG.md | 1 - 1 file changed, 1 deletion(-) diff --git a/projects/rccl/CHANGELOG.md b/projects/rccl/CHANGELOG.md index e837a0efd603..19c171208010 100644 --- a/projects/rccl/CHANGELOG.md +++ b/projects/rccl/CHANGELOG.md @@ -7,7 +7,6 @@ Full documentation for RCCL is available at [https://rccl.readthedocs.io](https: ### Added ### Changed -* gfx950 tuner table: Broadcast and Reduce on 1 node x 8 GPUs from 512 KiB to 8 MiB now run Ring/LL (112 channels below 2 MiB), 1.5x to 3x faster than the previous Ring/Simple choice. ### Removed