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From: Alexander Kozyrev <akozyrev@nvidia.com>
To: <dev@dpdk.org>
Cc: <stable@dpdk.org>, <rasland@nvidia.com>, <viacheslavo@nvidia.com>,
	<matan@nvidia.com>, <orika@nvidia.com>
Subject: [dpdk-dev] [PATCH] net/mlx5: fix threshold for mbuf replenishment in MPRQ
Date: Mon, 12 Jul 2021 17:29:10 +0300	[thread overview]
Message-ID: <20210712142910.314572-1-akozyrev@nvidia.com> (raw)

The replenishment scheme for the vectorized MPRQ Rx burst aims
to improve the cache locality by allocating new mbufs only when
there are almost no mbufs left: one burst gap between allocated
and consumed indexes.

This gap is not big enough to accommodate a corner case when we
have a very aggressive CQE compression with up to 4 regular CQEs
and 64 zipped CQEs at the end.

Need to keep in mind this case and extend the replenishment
threshold by MLX5_VPMD_DESCS_PER_LOOP (4) to avoid mbuf overflow.

Fixes: 5fc2e5c27d6 ("net/mlx5: fix mbuf overflow in vectorized MPRQ")
Cc: stable@dpdk.org

Signed-off-by: Alexander Kozyrev <akozyrev@nvidia.com>
Acked-by: Viacheslav Ovsiienko <viacheslavo@nvidia.com>
---
 drivers/net/mlx5/mlx5_rxtx_vec.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/mlx5/mlx5_rxtx_vec.c b/drivers/net/mlx5/mlx5_rxtx_vec.c
index d5af2d91ff..e22ab665df 100644
--- a/drivers/net/mlx5/mlx5_rxtx_vec.c
+++ b/drivers/net/mlx5/mlx5_rxtx_vec.c
@@ -152,7 +152,8 @@ mlx5_rx_mprq_replenish_bulk_mbuf(struct mlx5_rxq_data *rxq)
 	unsigned int i;
 
 	if (n >= rxq->rq_repl_thresh &&
-	    rxq->elts_ci - rxq->rq_pi <= rxq->rq_repl_thresh) {
+	    rxq->elts_ci - rxq->rq_pi <=
+	    (uint32_t)rxq->rq_repl_thresh + MLX5_VPMD_DESCS_PER_LOOP) {
 		MLX5_ASSERT(n >= MLX5_VPMD_RXQ_RPLNSH_THRESH(elts_n));
 		MLX5_ASSERT(MLX5_VPMD_RXQ_RPLNSH_THRESH(elts_n) >
 			     MLX5_VPMD_DESCS_PER_LOOP);
-- 
2.18.2


             reply	other threads:[~2021-07-12 14:29 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-12 14:29 Alexander Kozyrev [this message]
2021-07-13 15:21 ` [dpdk-dev] [PATCH v2] " Alexander Kozyrev
2021-07-14 11:57   ` Raslan Darawsheh

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