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 at 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 at linux.intel.com>
--yliu
