Re: [dpdk-stable] [dpdk-dev] [PATCH 1/1] net/qede: fix receive packet drop

[Rasesh Mody <rmody@marvell.com>]

>From: dev <dev-bounces@dpdk.org> On Behalf Of Shahed Shaikh
>Sent: Tuesday, March 12, 2019 9:51 AM
>
>There is a corner case in which driver won't post receive buffers when driver
>has processed all received packets in single loop (i.e. hw_consumer ==
>sw_consumer) and then HW will start dropping packets since it did not see
>new receive buffers posted.
>
>This corner case is seen when size of Rx ring is less than or equals Rx packet
>burst count for dev->rx_pkt_burst().
>
>Fixes: 8f2312474529 ("net/qede: fix performance bottleneck in Rx path")
>Cc: stable@dpdk.org
>
>Signed-off-by: Shahed Shaikh <shshaikh@marvell.com>
>---

Acked-by: Rasesh Mody <rmody@marvell.com>

> drivers/net/qede/qede_rxtx.c | 15 ++++++++-------
> 1 file changed, 8 insertions(+), 7 deletions(-)
>
>diff --git a/drivers/net/qede/qede_rxtx.c b/drivers/net/qede/qede_rxtx.c
>index 70c32e3..27bac09 100644
>--- a/drivers/net/qede/qede_rxtx.c
>+++ b/drivers/net/qede/qede_rxtx.c
>@@ -1420,13 +1420,6 @@ qede_recv_pkts(void *p_rxq, struct rte_mbuf
>**rx_pkts, uint16_t nb_pkts)
> 	uint32_t rss_hash;
> 	int rx_alloc_count = 0;
>
>-	hw_comp_cons = rte_le_to_cpu_16(*rxq->hw_cons_ptr);
>-	sw_comp_cons = ecore_chain_get_cons_idx(&rxq->rx_comp_ring);
>-
>-	rte_rmb();
>-
>-	if (hw_comp_cons == sw_comp_cons)
>-		return 0;
>
> 	/* Allocate buffers that we used in previous loop */
> 	if (rxq->rx_alloc_count) {
>@@ -1447,6 +1440,14 @@ qede_recv_pkts(void *p_rxq, struct rte_mbuf
>**rx_pkts, uint16_t nb_pkts)
> 		rxq->rx_alloc_count = 0;
> 	}
>
>+	hw_comp_cons = rte_le_to_cpu_16(*rxq->hw_cons_ptr);
>+	sw_comp_cons = ecore_chain_get_cons_idx(&rxq->rx_comp_ring);
>+
>+	rte_rmb();
>+
>+	if (hw_comp_cons == sw_comp_cons)
>+		return 0;
>+
> 	while (sw_comp_cons != hw_comp_cons) {
> 		ol_flags = 0;
> 		packet_type = RTE_PTYPE_UNKNOWN;
>--
>2.7.4