feat(rccl): Scaleup Allreduce using GIN/LSA by nusislam · Pull Request #10783 · ROCm/rocm-systems

nusislam · 2026-08-26T18:29:07Z

Motivation

This PR develops scaleup allreduce algorithms using LSA/GIN APIs.

Technical Details

For small/medium message sizes, LSA-based one-shot and two-shot algorithms are used. For large sizes, GIN-based Allreduce kernel is used. Since this is an Allreduce for the scaleup domain, the SDMA-backend for GIN is used for large sizes. This feature requires symmetric memory window registration.

This PR is based on #10386 that has build fixes for GIN SDMA backend.

Issue Tracking

AICOMRCCL-1897

Test Plan

rccl-tests allreduce
unit tests (TODO)

Test Result

For large messages, GIN Allreduce achieves peak bandwidth.

Submission Checklist

Look over the contributing guidelines at https://github.com/ROCm/rocm-systems/blob/develop/CONTRIBUTING.md.

therock-pr-bot · 2026-08-26T18:29:46Z

❌ PR Check — Action Required

Check	Status	Details
📝 PR Description	❌ Fail	Error: PR description must reference a JIRA ID, ISSUE ID, or a GitHub closing keyword. Expected: include a `JIRA ID` / `ISSUE ID` line (separator `:` or `-`, or omitted; value may be a JIRA key, a number with/without `#`, or a link), OR a closing keyword + issue reference. Accepted examples: • `JIRA ID : TESTAUTO-6039` • `JIRA ID - #330` • `JIRA ID #330` • `JIRA ID` (on separate line) `ROCM-25757` • `ISSUE ID : TESTUTO-3334` • `ISSUE ID #3334` • `ISSUE ID - TESTAUTO-3433` • `ISSUE ID` (on separate line) `AIRUNTIME-2352` • `ISSUE ID : https://github.com/<org_name>/<repo_name>/issues/1234` • `Closes #10` • `Fixes octo-org/octo-repo#100` • `Resolves: #123` • `#123` • `https://github.com/<org_name>/<repo_name>/issues/123` Current: no valid JIRA/ISSUE/closing-keyword reference found
⛔ Forbidden Files	✅ Pass	—
🧪 Unit Test	✅ Pass	—
🔎 pre-commit	⏳ Pending	⏳ Still running…
🚫 Draft PR	🔜 To Be Enabled	—
🚩 Feature Flag	🔜 To Be Enabled	—
📊 Code Coverage	🔜 To Be Enabled	—

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therock-pr-bot · 2026-08-26T18:29:48Z

🚫 Please fix the failed policies before requesting reviews.

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Copilot

Pull request overview

This PR adds GIN/LSA-based “scaleup-only” (single-node) fast paths to RCCL collectives, introducing new SDMA-backed GIN implementations for AllToAll and AllReduce and wiring them into the collective dispatch.

Changes:

Adds GIN-SDMA AllToAll and AllReduce implementations (new kernels + host entry points) and dispatch hooks in collectives.cc.
Extends communicator state and teardown to manage GIN internal dev comms and associated resources.
Updates build/DeviceLinker integration for new HIP objects and adjusts ROCm linking/CI coverage for GIN-SDMA.

Reviewed changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
projects/rccl/tools/ci/lib/gin-tests.json	Adds a new CI test variant for internal GIN-SDMA runs.
projects/rccl/src/init.cc	Ensures GIN-SDMA resources are finalized during communicator teardown.
projects/rccl/src/include/comm.h	Extends `ncclComm` with GIN-SDMA per-comm state structs and includes new headers.
projects/rccl/src/collectives.cc	Routes eligible AllToAll/AllReduce calls to the new GIN-SDMA paths.
projects/rccl/src/CMakeLists.txt	Adds new headers/sources and adjusts linking (hsakmt discovery, rocSHMEM host object extraction).
projects/rccl/src/algorithms/gin/sdma/gin_alltoall_sdma.cu	New GIN-SDMA AllToAll kernel + eligibility/launch/finalize.
projects/rccl/src/algorithms/gin/sdma/gin_all_reduce_sdma.cu	New GIN-SDMA AllReduce algorithms (LSA one/two-shot and GIN two-shot) + state management.
projects/rccl/src/algorithms/gin/sdma/all_reduce_gin_sdma.h	New device kernels/utilities backing the AllReduce implementations.
projects/rccl/src/algorithms/gin/gin_alltoall.h	Declares AllToAll GIN-SDMA host APIs and per-comm state.
projects/rccl/src/algorithms/gin/gin_all_reduce.h	Declares AllReduce GIN-SDMA host APIs, thresholds, and per-comm state.
projects/rccl/cmake/DeviceLinker.cmake	Adds device-linker compilation rules for new GIN-SDMA HIP fat objects and adjusts rocSHMEM bitcode behavior.

Suppressed comments (1)

projects/rccl/src/algorithms/gin/sdma/gin_all_reduce_sdma.cu:116

msgSize is computed but never used, which can trigger an unused-variable warning (and break builds when warnings are treated as errors).

  size_t msgSize = countPerRank * sizeof(T) * comm->nRanks;

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nusislam · 2026-08-28T19:59:09Z

@copilot resolve the merge conflicts in this pull request

Copilot · 2026-08-28T20:05:42Z

@copilot resolve the merge conflicts in this pull request

Resolved the merge conflict in gin-tests.json, retaining both the internal RCCL SDMA test and the develop fixture test. The fix is in merge commit 6336ba162f.

nusislam · 2026-08-29T17:00:33Z

@dlamd1dai , @Kapil-Shyam-Pawar - please review.

github-actions · 2026-08-29T17:04:36Z

RCCL Perf-Regression Gate: ⚠️ NO VERDICT (not measured)

This run did not produce a usable answer. It is neither a PASS nor a regression — treat the perf gate as not run for this change.

Why:

this report predates the trustworthiness flag, or a group could not be scored

Mode: detect (reference vs candidate)
Thresholds: small 17.2% · mid 12.3% · large 12.9%
Keys compared: 0 · Confirmed regressions: 0 · Inconclusive: 0
Provenance: n/a

Per-collective breakdown

group	keys	regressions	inconclusive
all_gather_perf-d=bfloat16-default	0	0	0
all_gather_perf-d=float-default	0	0	0
all_reduce_perf-d=bfloat16-default	0	0	0
all_reduce_perf-d=float-default	0	0	0
broadcast_perf-d=bfloat16-default	0	0	0
broadcast_perf-d=float-default	0	0	0
reduce_scatter_perf-d=bfloat16-default	0	0	0
reduce_scatter_perf-d=float-default	0	0	0

nusislam · 2026-08-31T20:01:48Z

@dlamd1dai - Please review this PR.

nusislam · 2026-09-01T18:06:48Z

@Kapil-Shyam-Pawar - I have addressed your reviews. Please take a look.

nusislam · 2026-09-02T12:55:29Z

@wenkaidu - Can you please review this PR?

Co-authored-by: nusislam <25847498+nusislam@users.noreply.github.com>

amd-argus

Automated Review Guard for Upfront Scrutiny

Bottom line: No correctness defect found in the kernels. Two things worth settling before merge: the new eligibility suite passes even if ncclAllReduceGinSdmaEligible returns false, and the yield-to-DDA override reroutes symmetric AllReduces GIN never claims.

_{Comment @argus review to re-run, or @argus re-review after pushing.}

dlamd1dai

Re-review of the GIN two-shot default path after the selector and intra-GPU barrier updates. Two follow-ups on ginAllReduceTwoShotKernel.

Co-authored-by: amd-argus[bot] <321830313+amd-argus[bot]@users.noreply.github.com>

nusislam · 2026-09-06T14:56:16Z

The test failures are not related to this PR.

## Motivation This PR develops scaleup allreduce algorithms using LSA/GIN APIs. ## Technical Details For small/medium message sizes, LSA-based one-shot and two-shot algorithms are used. For large sizes, GIN-based Allreduce kernel is used. Since this is an Allreduce for the scaleup domain, the SDMA-backend for GIN is used for large sizes. This feature requires symmetric memory window registration. This PR is based on ROCm#10386 that has build fixes for GIN SDMA backend. ## Issue Tracking AICOMRCCL-1897 ## Test Plan rccl-tests allreduce unit tests (TODO) ## Test Result For large messages, GIN Allreduce achieves peak bandwidth. ## Submission Checklist - [ ] Look over the contributing guidelines at https://github.com/ROCm/rocm-systems/blob/develop/CONTRIBUTING.md. --------- Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com> Co-authored-by: nusislam <25847498+nusislam@users.noreply.github.com> Co-authored-by: amd-argus[bot] <321830313+amd-argus[bot]@users.noreply.github.com> Signed-off-by: Jihyeon Gim <potatogim@potatogim.net>

systems-assistant · 2026-09-08T03:34:21Z

TheRock Submodule Bump Activity

Newest first

2026-09-08 — Included in TheRock via ROCm/TheRock#7974.

## Motivation This PR develops scaleup allreduce algorithms using LSA/GIN APIs. ## Technical Details For small/medium message sizes, LSA-based one-shot and two-shot algorithms are used. For large sizes, GIN-based Allreduce kernel is used. Since this is an Allreduce for the scaleup domain, the SDMA-backend for GIN is used for large sizes. This feature requires symmetric memory window registration. This PR is based on #10386 that has build fixes for GIN SDMA backend. ## Issue Tracking AICOMRCCL-1897 ## Test Plan rccl-tests allreduce unit tests (TODO) ## Test Result For large messages, GIN Allreduce achieves peak bandwidth. ## Submission Checklist - [ ] Look over the contributing guidelines at https://github.com/ROCm/rocm-systems/blob/develop/CONTRIBUTING.md. --------- Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com> Co-authored-by: nusislam <25847498+nusislam@users.noreply.github.com> Co-authored-by: amd-argus[bot] <321830313+amd-argus[bot]@users.noreply.github.com>

nusislam requested review from a team and a lite review from Copilot August 26, 2026 18:29

github-actions Bot added the project: rccl label Aug 26, 2026

therock-pr-bot Bot added the Not ready to Review label Aug 26, 2026

Copilot started reviewing on behalf of nusislam August 26, 2026 18:29

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Copilot AI reviewed Aug 26, 2026

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Comment thread projects/rccl/src/collectives.cc Resolved

Comment thread projects/rccl/src/algorithms/gin/sdma/gin_all_reduce_sdma.cu Resolved

Comment thread projects/rccl/src/algorithms/gin/sdma/all_reduce_gin_sdma.h Resolved

systems-assistant Bot added the organization: ROCm label Aug 26, 2026

Copilot started work on behalf of nusislam August 28, 2026 19:59

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Copilot finished work on behalf of nusislam August 28, 2026 20:06

Kapil-Shyam-Pawar reviewed Aug 30, 2026

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Copilot started work on behalf of nusislam August 30, 2026 15:21

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Copilot finished work on behalf of nusislam August 30, 2026 15:27

Kapil-Shyam-Pawar reviewed Aug 30, 2026

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Comment thread projects/rccl/src/algorithms/gin/sdma/gin_all_reduce_sdma.cu Resolved

Comment thread projects/rccl/src/algorithms/gin/sdma/gin_all_reduce_sdma.cu Resolved

Comment thread projects/rccl/src/algorithms/gin/sdma/all_reduce_gin_sdma.h Resolved

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Comment thread projects/rccl/src/algorithms/gin/sdma/all_reduce_gin_sdma.h Resolved

nusislam removed the Not ready to Review label Sep 1, 2026

Kapil-Shyam-Pawar reviewed Sep 1, 2026

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Comment thread projects/rccl/test/gin/gin_all_reduce_policy_test.cpp Resolved

Comment thread projects/rccl/src/algorithms/gin/sdma/gin_all_reduce_sdma.cu Resolved

Kapil-Shyam-Pawar approved these changes Sep 1, 2026

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Comment thread projects/rccl/src/algorithms/gin/sdma/all_reduce_gin_sdma.h Resolved

Comment thread projects/rccl/src/collectives.cc Resolved

therock-pr-bot Bot added the Not ready to Review label Sep 2, 2026

nusislam removed the Not ready to Review label Sep 2, 2026

nusislam and others added 14 commits September 2, 2026 13:49

add GIN LSA-SDMA Allreduce

52419aa

build fix

2cdfde2

graph capture fix

69dffcf

fix for bf16

2db6721

add an environment variable for GIN AR

51fc9ec

Complete merge conflict resolution

7e18e37

Co-authored-by: nusislam <25847498+nusislam@users.noreply.github.com>

add tests for gin allreduce

910b78e

update CMakeList for tests

bd1a273

Remove accidental module cache lock

685a01f

Co-authored-by: nusislam <25847498+nusislam@users.noreply.github.com>

address review comments

4288a2e

build fix

5a5b4f7

add intra-gpu CTA barrier for gin AR kernel

b4858c9

address reviews

186ecad

remove unused env variable

506b3e4

nusislam force-pushed the users/nusislam/gin-ar-pr branch from cdaf1fe to 506b3e4 Compare September 2, 2026 19:54

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Comment thread projects/rccl/src/algorithms/gin/sdma/all_reduce_gin_sdma.h Resolved

Comment thread projects/rccl/src/algorithms/gin/sdma/all_reduce_gin_sdma.h Resolved

nusislam and others added 5 commits September 3, 2026 09:08

Merge branch 'develop' into users/nusislam/gin-ar-pr

ef0f3d9

Update projects/rccl/src/algorithms/gin/sdma/all_reduce_gin_sdma.h

3e1d90a

Co-authored-by: amd-argus[bot] <321830313+amd-argus[bot]@users.noreply.github.com>

Update projects/rccl/src/algorithms/gin/sdma/gin_all_reduce_sdma.cu

c342284

Co-authored-by: amd-argus[bot] <321830313+amd-argus[bot]@users.noreply.github.com>

address reviews

21fec7e

cleanup

42ea7b1

nusislam merged commit 72ee0a5 into develop Sep 6, 2026
46 of 49 checks passed

nusislam deleted the users/nusislam/gin-ar-pr branch September 6, 2026 14:56

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Motivation

Technical Details

Issue Tracking

Test Plan

Test Result

Submission Checklist

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Pull request overview

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nusislam commented Aug 28, 2026

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github-actions Bot commented Aug 29, 2026

RCCL Perf-Regression Gate: ⚠️ NO VERDICT (not measured)

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nusislam commented Aug 31, 2026

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nusislam commented Sep 6, 2026

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TheRock Submodule Bump Activity

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