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virtio: clean up Tx space checks

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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.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
Acked-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
This commit is contained in:
Stephen Hemminger 2015-12-03 17:12:54 -08:00 committed by Thomas Monjalon
parent c21835fab8
commit 43ffe8aa86
1 changed files with 31 additions and 41 deletions
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72
drivers/net/virtio/virtio_rxtx.c
View File

@ -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;
/*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;
}
/*
* Zero or negative value indicates it has enough free
* descriptors to use for transmitting.
*/
if (likely(need <= 0)) {
txm = tx_pkts[nb_tx];
/* Do VLAN tag insertion */
if (unlikely(txm->ol_flags & PKT_TX_VLAN_PKT)) {
error = rte_vlan_insert(&txm);
if (unlikely(error)) {
rte_pktmbuf_free(txm);
++nb_tx;
continue;
}
}
/* Enqueue Packet buffers */
error = virtqueue_enqueue_xmit(txvq, txm);
if (unlikely(error)) {
if (error == ENOSPC)
PMD_TX_LOG(ERR, "virtqueue_enqueue Free count = 0");
else if (error == EMSGSIZE)
PMD_TX_LOG(ERR, "virtqueue_enqueue Free count < 1");
else
PMD_TX_LOG(ERR, "virtqueue_enqueue error: %d", error);
need = txm->nb_segs - txvq->vq_free_cnt + 1;
if (unlikely(need > 0)) {
PMD_TX_LOG(ERR,
"No free tx descriptors to transmit");
break;
}
nb_tx++;
txvq->bytes += txm->pkt_len;
virtio_update_packet_stats(txvq, txm);
} else {
PMD_TX_LOG(ERR, "No free tx descriptors to transmit");
}
/* Do VLAN tag insertion */
if (unlikely(txm->ol_flags & PKT_TX_VLAN_PKT)) {
error = rte_vlan_insert(&txm);
if (unlikely(error)) {
rte_pktmbuf_free(txm);
continue;
}
}
/* Enqueue Packet buffers */
error = virtqueue_enqueue_xmit(txvq, txm);
if (unlikely(error)) {
if (error == ENOSPC)
PMD_TX_LOG(ERR, "virtqueue_enqueue Free count = 0");
else if (error == EMSGSIZE)
PMD_TX_LOG(ERR, "virtqueue_enqueue Free count < 1");
else
PMD_TX_LOG(ERR, "virtqueue_enqueue error: %d", error);
break;
}
txvq->bytes += txm->pkt_len;
virtio_update_packet_stats(txvq, txm);
}
txvq->packets += nb_tx;