From: Yuanhan Liu <yuanhan.liu@linux.intel.com>
To: Stephen Hemminger <stephen@networkplumber.org>
Cc: dev@dpdk.org
Subject: Re: [dpdk-dev] [PATCH 2/2] virtio: clean up space checks on xmit
Date: Fri, 4 Dec 2015 11:28:58 +0800 [thread overview]
Message-ID: <20151204032858.GB29571@yliu-dev.sh.intel.com> (raw)
In-Reply-To: <1449191574-14629-3-git-send-email-stephen@networkplumber.org>
On Thu, Dec 03, 2015 at 05:12:54PM -0800, Stephen Hemminger wrote:
> The space check for transmit ring only needs a single conditional.
> I.e only need to recheck for space if there was no space in first check.
>
> This can help performance and simplifies loop.
This is a good cleanup. Besides that, I have few minor comments below.
>
> Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
> ---
> drivers/net/virtio/virtio_rxtx.c | 68 +++++++++++++++++-----------------------
> 1 file changed, 29 insertions(+), 39 deletions(-)
>
> diff --git a/drivers/net/virtio/virtio_rxtx.c b/drivers/net/virtio/virtio_rxtx.c
> index 466fee6..7cb932a 100644
> --- a/drivers/net/virtio/virtio_rxtx.c
> +++ b/drivers/net/virtio/virtio_rxtx.c
> @@ -832,7 +832,6 @@ uint16_t
> virtio_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts, uint16_t nb_pkts)
> {
> struct virtqueue *txvq = tx_queue;
> - struct rte_mbuf *txm;
> uint16_t nb_used, nb_tx;
> int error;
>
> @@ -846,58 +845,49 @@ virtio_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts, uint16_t nb_pkts)
> if (likely(nb_used > txvq->vq_nentries - txvq->vq_free_thresh))
> virtio_xmit_cleanup(txvq, nb_used);
>
> - nb_tx = 0;
> -
> - while (nb_tx < nb_pkts) {
> + for (nb_tx = 0; nb_tx < nb_pkts; nb_tx++) {
> + struct rte_mbuf *txm = tx_pkts[nb_tx];
> /* Need one more descriptor for virtio header. */
> - int need = tx_pkts[nb_tx]->nb_segs - txvq->vq_free_cnt + 1;
> + int need = txm->nb_segs - txvq->vq_free_cnt + 1;
While reviewing the code, I found the var name `need' is not properly
taken. Maybe `need_cleanup' is better, and it's better to be defined
as bool type. What do you think of that?
(And yes, it has nothing to do with your patch, I just found it we
can rename it to a better name to improve the code readability a bit.
If you agree, would you submit a patch, or should I do it?)
>
> - /*Positive value indicates it need free vring descriptors */
> + /* Positive value indicates it need free vring descriptors */
> if (unlikely(need > 0)) {
> nb_used = VIRTQUEUE_NUSED(txvq);
> virtio_rmb();
> need = RTE_MIN(need, (int)nb_used);
>
> virtio_xmit_cleanup(txvq, need);
> - need = (int)tx_pkts[nb_tx]->nb_segs -
> - txvq->vq_free_cnt + 1;
> + need = txm->nb_segs - txvq->vq_free_cnt + 1;
> + if (unlikely(need > 0)) {
> + PMD_TX_LOG(ERR,
> + "No free tx descriptors to transmit");
> + break;
> + }
^
Minor nit: I found a leading white space there.
Otherwise, it looks good:
Acked-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
--yliu
next prev parent reply other threads:[~2015-12-04 3:28 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-04 1:12 [dpdk-dev] [PATCH 0/2] virtio: bugfix and cleanup Stephen Hemminger
2015-12-04 1:12 ` [dpdk-dev] [PATCH 1/2] virtio: make sure rcv mbuf initialized correctly Stephen Hemminger
2015-12-04 3:18 ` Yuanhan Liu
2015-12-04 1:12 ` [dpdk-dev] [PATCH 2/2] virtio: clean up space checks on xmit Stephen Hemminger
2015-12-04 3:28 ` Yuanhan Liu [this message]
2015-12-05 19:50 ` Stephen Hemminger
2015-12-08 1:54 ` Yuanhan Liu
2015-12-06 23:02 ` [dpdk-dev] [PATCH 0/2] virtio: bugfix and cleanup Thomas Monjalon
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