UCT/GDA: Use wqe_idx for rc_gda progress #10928
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Artemy-Mellanox
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yosefe
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Sep 30, 2025
| if (req != nullptr) { | ||
| comp = &req->comp; | ||
| req->device_ep = device_ep; | ||
| uct_device_completion_init(comp); |
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can also remove the TODO comment
src/uct/api/device/uct_device_impl.h
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| #include <uct/ib/mlx5/gdaki/gdaki.cuh> | ||
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| union uct_device_completion { | ||
| uct_rc_gda_completion_t rc; |
src/uct/ib/mlx5/gdaki/gdaki.cuh
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| 0xffffff); | ||
| uct_rc_mlx5_gda_qedump("WQE", wqe_ptr, 64); | ||
| uct_rc_mlx5_gda_qedump("CQE", cqe64, 64); | ||
| ep->wqe_error = ep->sq_wqe_pi; |
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Do we need some "atomic write" so it will be visible to all threads?
src/uct/ib/mlx5/gdaki/gdaki.cuh
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| if (ep->wqe_error && comp->wqe_idx < ep->wqe_error) { | ||
| return UCS_ERR_IO_ERROR; | ||
| } | ||
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| status = (ucs_status_t)__shfl_sync(0xffffffff, status, 0); | ||
| __syncwarp(); | ||
| return status; | ||
| } else if (level == UCS_DEVICE_LEVEL_THREAD) { | ||
| return uct_rc_mlx5_gda_progress_thread(ep); | ||
| } else { | ||
| return UCS_ERR_UNSUPPORTED; | ||
| if (ep->sq_wqe_pi <= comp->wqe_idx) { |
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- why need to check ep->wqe_error separately?
IMOcomp->wqe_idx < ep->wqe_erroris enough - do we need some kind of atomic read/write for ep->wqe_error?
- maybe rename ep->wqe_error to ep->wqe_error_pi?
- if another thread updated ep->sq_wqe_pi but didn't yet update ep->wqe_error, we might think some tl_comp is success, while in fact it is failure.
src/uct/ib/mlx5/gdaki/gdaki_dev.h
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| uint64_t cqe_ci; | ||
| int sq_lock; | ||
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| uint64_t wqe_error; |
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maybe move it after sq_wqe_pi?
iyastreb
previously approved these changes
Oct 2, 2025
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iyastreb
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I tested with many threads, no hangs and perf is better than before:
-O 32 -T 1 7.7us
-O 32 -T 32 159us
-O 32 -T 64 153us
-O 16 -T 128 372us
-O 8 -T 256 1169us
-O 4 -T 512 1768us
Contributor
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This PR was hanging in cuda kernel perftest. So may be there is a real issue. |
iyastreb
approved these changes
Oct 6, 2025
This was referenced Oct 8, 2025
zzhang37
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Oct 16, 2025
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