net/mlx5: fix Rx buffer replenishment threshold

The threshold of buffer replenishment for vectorized Rx burst is a constant
value (64). If the size of Rx queue is comparatively small, device could
run out of buffers. For example, if the size of Rx queue is 128, buffers
are replenished only twice per a wraparound. This can cause jitter in
receiving packets and the jitter can cause unnecessary retransmission for
TCP connections.

Fixes: 6cb559d67b83 ("net/mlx5: add vectorized Rx/Tx burst for x86")
Fixes: 570acdb1da8a ("net/mlx5: add vectorized Rx/Tx burst for ARM")
Cc: stable@dpdk.org
Signed-off-by: Yongseok Koh <yskoh@mellanox.com>
Acked-by: Shahaf Shuler <shahafs@mellanox.com>

diff --git a/drivers/net/mlx5/mlx5_defs.h b/drivers/net/mlx5/mlx5_defs.h
index 51124cdcc5cd2349e7e88862ebe87cc1a91edd83..b52f7dcbe67a010f652344131c98b32be58dbf71 100644 (file)
--- a/drivers/net/mlx5/mlx5_defs.h
+++ b/drivers/net/mlx5/mlx5_defs.h
@@ -64,10 +64,11 @@
 #define MLX5_VPMD_MIN_TXQS 4
 
 /* Threshold of buffer replenishment for vectorized Rx. */
-#define MLX5_VPMD_RXQ_RPLNSH_THRESH   64U
+#define MLX5_VPMD_RXQ_RPLNSH_THRESH(n) \
+       (RTE_MIN(MLX5_VPMD_RX_MAX_BURST, (unsigned int)(n) >> 2))
 
 /* Maximum size of burst for vectorized Rx. */
-#define MLX5_VPMD_RX_MAX_BURST        MLX5_VPMD_RXQ_RPLNSH_THRESH
+#define MLX5_VPMD_RX_MAX_BURST 64U
 
 /*
  * Maximum size of burst for vectorized Tx. This is related to the maximum size

diff --git a/drivers/net/mlx5/mlx5_rxtx_vec.h b/drivers/net/mlx5/mlx5_rxtx_vec.h
index 598dc7519bb49f53292f6e19c9250f073b116a95..fb884f92fd0c5fa4ea4ff8cb832e7c3ac776ee07 100644 (file)
--- a/drivers/net/mlx5/mlx5_rxtx_vec.h
+++ b/drivers/net/mlx5/mlx5_rxtx_vec.h
@@ -91,9 +91,9 @@ mlx5_rx_replenish_bulk_mbuf(struct mlx5_rxq_data *rxq, uint16_t n)
                &((volatile struct mlx5_wqe_data_seg *)rxq->wqes)[elts_idx];
        unsigned int i;
 
-       assert(n >= MLX5_VPMD_RXQ_RPLNSH_THRESH);
+       assert(n >= MLX5_VPMD_RXQ_RPLNSH_THRESH(q_n));
        assert(n <= (uint16_t)(q_n - (rxq->rq_ci - rxq->rq_pi)));
-       assert(MLX5_VPMD_RXQ_RPLNSH_THRESH > MLX5_VPMD_DESCS_PER_LOOP);
+       assert(MLX5_VPMD_RXQ_RPLNSH_THRESH(q_n) > MLX5_VPMD_DESCS_PER_LOOP);
        /* Not to cross queue end. */
        n = RTE_MIN(n - MLX5_VPMD_DESCS_PER_LOOP, q_n - elts_idx);
        if (rte_mempool_get_bulk(rxq->mp, (void *)elts, n) < 0) {

diff --git a/drivers/net/mlx5/mlx5_rxtx_vec_neon.h b/drivers/net/mlx5/mlx5_rxtx_vec_neon.h
index 71a5eaf23eab84ebbba4b143ea808f637063cc5f..3ebf34823ed846bef168578fa9c618c8576d7fa6 100644 (file)
--- a/drivers/net/mlx5/mlx5_rxtx_vec_neon.h
+++ b/drivers/net/mlx5/mlx5_rxtx_vec_neon.h
@@ -739,7 +739,7 @@ rxq_burst_v(struct mlx5_rxq_data *rxq, struct rte_mbuf **pkts, uint16_t pkts_n,
         *   N - (rq_ci - rq_pi) := # of buffers consumed (to be replenished).
         */
        repl_n = q_n - (rxq->rq_ci - rxq->rq_pi);
-       if (repl_n >= MLX5_VPMD_RXQ_RPLNSH_THRESH)
+       if (repl_n >= MLX5_VPMD_RXQ_RPLNSH_THRESH(q_n))
                mlx5_rx_replenish_bulk_mbuf(rxq, repl_n);
        /* See if there're unreturned mbufs from compressed CQE. */
        rcvd_pkt = rxq->cq_ci - rxq->rq_pi;

diff --git a/drivers/net/mlx5/mlx5_rxtx_vec_sse.h b/drivers/net/mlx5/mlx5_rxtx_vec_sse.h
index 3e985d61d553b54b430b49f0872b17fb68a1d2f2..f0d88883104a8c5accbb5c901d6f4f5455b71503 100644 (file)
--- a/drivers/net/mlx5/mlx5_rxtx_vec_sse.h
+++ b/drivers/net/mlx5/mlx5_rxtx_vec_sse.h
@@ -724,7 +724,7 @@ rxq_burst_v(struct mlx5_rxq_data *rxq, struct rte_mbuf **pkts, uint16_t pkts_n,
         *   N - (rq_ci - rq_pi) := # of buffers consumed (to be replenished).
         */
        repl_n = q_n - (rxq->rq_ci - rxq->rq_pi);
-       if (repl_n >= MLX5_VPMD_RXQ_RPLNSH_THRESH)
+       if (repl_n >= MLX5_VPMD_RXQ_RPLNSH_THRESH(q_n))
                mlx5_rx_replenish_bulk_mbuf(rxq, repl_n);
        /* See if there're unreturned mbufs from compressed CQE. */
        rcvd_pkt = rxq->cq_ci - rxq->rq_pi;