From: "Xie, Huawei" <huawei.xie@intel.com>
To: Tom Kiely <tkiely@brocade.com>, "dev@dpdk.org" <dev@dpdk.org>
Subject: Re: [dpdk-dev] [PATCH] virtio: fix rx ring descriptor starvation
Date: Wed, 25 Nov 2015 17:32:57 +0000 [thread overview]
Message-ID: <C37D651A908B024F974696C65296B57B4B1B2353@SHSMSX101.ccr.corp.intel.com> (raw)
In-Reply-To: <1447407013-6986-1-git-send-email-tkiely@brocade.com>
On 11/13/2015 5:33 PM, Tom Kiely wrote:
> If all rx descriptors are processed while transient
> mbuf exhaustion is present, the rx ring ends up with
> no available descriptors. Thus no packets are received
> on that ring. Since descriptor refill is performed post
> rx descriptor processing, in this case no refill is
> ever subsequently performed resulting in permanent rx
> traffic drop.
>
> Signed-off-by: Tom Kiely <tkiely@brocade.com>
> ---
> drivers/net/virtio/virtio_rxtx.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/virtio/virtio_rxtx.c b/drivers/net/virtio/virtio_rxtx.c
> index 5770fa2..a95e234 100644
> --- a/drivers/net/virtio/virtio_rxtx.c
> +++ b/drivers/net/virtio/virtio_rxtx.c
> @@ -586,7 +586,8 @@ virtio_recv_pkts(void *rx_queue, struct rte_mbuf **rx_pkts, uint16_t nb_pkts)
> if (likely(num > DESC_PER_CACHELINE))
> num = num - ((rxvq->vq_used_cons_idx + num) % DESC_PER_CACHELINE);
>
> - if (num == 0)
> + /* Refill free descriptors even if no pkts recvd */
> + if (num == 0 && virtqueue_full(rxvq))
Should the return condition be that no used buffers and we have avail
descs in avail ring, i.e,
num == 0 && rxvq->vq_free_cnt != rxvq->vq_nentries
rather than
num == 0 && rxvq->vq_free_cnt == 0
?
> return 0;
>
> num = virtqueue_dequeue_burst_rx(rxvq, rcv_pkts, len, num);
> @@ -683,7 +684,8 @@ virtio_recv_mergeable_pkts(void *rx_queue,
>
> virtio_rmb();
>
> - if (nb_used == 0)
> + /* Refill free descriptors even if no pkts recvd */
> + if (nb_used == 0 && virtqueue_full(rxvq))
> return 0;
>
> PMD_RX_LOG(DEBUG, "used:%d\n", nb_used);
next prev parent reply other threads:[~2015-11-25 17:33 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-11-13 9:30 Tom Kiely
2015-11-24 21:20 ` Thomas Monjalon
2015-11-25 1:50 ` Yuanhan Liu
2015-11-25 2:51 ` Xie, Huawei
2015-11-25 17:32 ` Xie, Huawei [this message]
[not found] ` <C37D651A908B024F974696C65296B57B4C545F75@SHSMSX101.ccr.corp.intel.com>
2015-12-17 9:22 ` Tom Kiely
2015-12-17 11:18 ` Tom Kiely
2016-01-05 7:13 ` Xie, Huawei
2016-02-10 15:07 ` Bruce Richardson
2016-02-18 14:03 ` Kyle Larose
2016-02-22 16:23 ` Tom Kiely
2016-02-23 8:26 ` Xie, Huawei
2016-03-04 6:16 ` Xie, Huawei
2016-03-04 8:11 ` Tom Kiely
2016-03-04 13:25 ` Kyle Larose
2016-03-09 21:37 ` Bruce Richardson
2016-03-10 14:46 ` Kyle Larose
2016-02-26 18:58 Kyle Larose
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