Fix FlyDSL split-k barrier synchronization issue#2877
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XiaobingSuper wants to merge 4 commits intomainfrom
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Fix FlyDSL split-k barrier synchronization issue#2877XiaobingSuper wants to merge 4 commits intomainfrom
XiaobingSuper wants to merge 4 commits intomainfrom
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Pull request overview
Updates FlyDSL’s split-k HGEMM synchronization to use a per-dispatch 64-bit token protocol (based on dispatch_id) to remain correct under graph replay while reducing host-side state and polling overhead.
Changes:
- Replace rotating split-k “signal state” + int32 counters with an int64 per-dispatch token (
dispatch_id + 1, reserving0as invalid) and release/acquire publish+poll. - Remove host-managed split-k state rotation and shrink the global semaphore to a single int64 counter array.
- Reduce barrier polling overhead by having only
tid==0poll the semaphore and then synchronizing the block withgpu.barrier().
Reviewed changes
Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.
| File | Description |
|---|---|
| aiter/ops/flydsl/kernels/splitk_hgemm.py | Switch split-k semaphore publish/poll to int64 dispatch tokens; remove stale-counter cleanup and signal_state plumbing. |
| aiter/ops/flydsl/kernels/small_m_hgemm.py | Mirror the int64 dispatch-token protocol for small-M split-k; remove stale-counter cleanup and signal_state. |
| aiter/ops/flydsl/gemm_kernels.py | Allocate a per-stream int64 semaphore (length 128) and remove host-side rotating split-k state management. |
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Replace the rotating split-k signal state with a 64-bit dispatch token barrier so split-k launches stay graph-safe and avoid stale-counter races. Narrow the polling and small_m publish waits to vmcnt-only to recover the lost performance while keeping the new protocol stable. Made-with: Cursor
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This reverts commit 033d8b9.
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Summary
Fix FlyDSL split-k barrier synchronization issue for graph mode