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UCT/IB/MLX5: Fix put_sgl_zcopy completion #11893

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Merged
evgeny-leksikov merged 2 commits into from
Sep 7, 2026
Merged

UCT/IB/MLX5: Fix put_sgl_zcopy completion #11893

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96a369b
UCT/IB/MLX5/RC: Fix put_sgl_zcopy completion
JeynmannZ Sep 3, 2026
cec4aa2
UCT/IB/MLX5: address comments
JeynmannZ Sep 4, 2026
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10 changes: 5 additions & 5 deletions src/uct/ib/mlx5/rc/rc_mlx5_ep.c
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Original file line number Diff line number Diff line change
Expand Up @@ -248,7 +248,7 @@ uct_rc_mlx5_base_ep_put_sgl_zcopy(uct_ep_h tl_ep, void * const *buffers,
struct mlx5_wqe_data_seg *dptr;
size_t wqe_size, i;
uint8_t fm_ce_se, fence_flag;
uint16_t sn, pi, res_count;
uint16_t pi, res_count;
uint64_t addr;
uct_rkey_t rkey;
void *curr;
Expand Down Expand Up @@ -283,12 +283,11 @@ uct_rc_mlx5_base_ep_put_sgl_zcopy(uct_ep_h tl_ep, void * const *buffers,
UCS_ERR_NO_RESOURCE, count - 1);

wqe_size = sizeof(*ctrl) + sizeof(*raddr) + sizeof(*dptr);
sn = txwq->sw_pi;
pi = txwq->sw_pi;

ucs_assert(!(txwq->flags & UCT_IB_MLX5_TXWQ_FLAG_FAILED));
ucs_assert(ucs_div_round_up(wqe_size, MLX5_SEND_WQE_BB) == 1);

pi = sn;
curr = txwq->curr;

fence = uct_rc_ep_fm(&iface->super, &txwq->fi, 1);
Expand Down Expand Up @@ -335,8 +334,9 @@ uct_rc_mlx5_base_ep_put_sgl_zcopy(uct_ep_h tl_ep, void * const *buffers,
uct_rc_mlx5_txwq_add_psn(txwq, IBV_QPT_RC, num_packets);

uct_rc_txqp_add_send_comp(&iface->super, &ep->super.txqp,
uct_rc_ep_send_op_completion_handler, comp, sn,
UCT_RC_IFACE_SEND_OP_FLAG_ZCOPY, NULL, 0, total);
uct_rc_ep_send_op_completion_handler, comp,
txwq->sig_pi, UCT_RC_IFACE_SEND_OP_FLAG_ZCOPY,

@svc-nvidia-pr-review svc-nvidia-pr-review Sep 3, 2026

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Change 1 — sn → txwq->sig_pi in uct_rc_txqp_add_send_comp: Correct and an improvement. Only the last WQE in the batch carries MLX5_WQE_CTRL_CQ_UPDATE, and its completion reports hw_ci = ntohs(cqe->wqe_counter) equal to that WQE's first BB index (prev_sw_pi after the loop). txwq->sig_pi is set to exactly txwq->prev_sw_pi, so UCS_CIRCULAR_COMPARE16(sig_pi, <=, hw_ci) matches on the right CQE. This aligns the SGL path with the signaled-PI convention used by uct_rc_mlx5_common_post_send, _flush, and _post_check. Removing the now-unused sn local is clean.

NULL, 0, total);

UCT_TL_EP_STAT_OP(&ep->super.super, PUT, ZCOPY, total);
uct_rc_ep_enable_flush_remote(&ep->super);
Expand Down