[v2] net/mlx5: fix threshold for mbuf replenishment in MPRQ
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Commit Message
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 multiple regular CQEs
at the beginning and 64 zipped CQEs at the end.
Need to keep in mind this case and extend the replenishment
threshold by MLX5_VPMD_RX_MAX_BURST (64) 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>
---
v2: increased the replenishment gap to MLX5_VPMD_RX_MAX_BURST
v1: https://patchwork.dpdk.org/project/dpdk/patch/20210712142910.314572-1-akozyrev@nvidia.com/
drivers/net/mlx5/mlx5_rxtx_vec.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
Comments
Hi,
> -----Original Message-----
> From: Alexander Kozyrev <akozyrev@nvidia.com>
> Sent: Tuesday, July 13, 2021 6:21 PM
> To: dev@dpdk.org
> Cc: Raslan Darawsheh <rasland@nvidia.com>; Matan Azrad
> <matan@nvidia.com>; Slava Ovsiienko <viacheslavo@nvidia.com>;
> stable@dpdk.org
> Subject: [PATCH v2] net/mlx5: fix threshold for mbuf replenishment in MPRQ
>
> 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 multiple regular CQEs
> at the beginning and 64 zipped CQEs at the end.
>
> Need to keep in mind this case and extend the replenishment
> threshold by MLX5_VPMD_RX_MAX_BURST (64) 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>
> ---
>
> v2: increased the replenishment gap to MLX5_VPMD_RX_MAX_BURST
> v1:
> https://patchwork.dpdk.org/project/dpdk/patch/20210712142910.314572-1-
> akozyrev@nvidia.com/
>
> drivers/net/mlx5/mlx5_rxtx_vec.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
Patch applied to next-net-mlx,
Kindest regards,
Raslan Darawsheh
@@ -157,7 +157,8 @@ 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 <=
+ rxq->rq_repl_thresh + MLX5_VPMD_RX_MAX_BURST) {
MLX5_ASSERT(n >= MLX5_VPMD_RXQ_RPLNSH_THRESH(elts_n));
MLX5_ASSERT(MLX5_VPMD_RXQ_RPLNSH_THRESH(elts_n) >
MLX5_VPMD_DESCS_PER_LOOP);