[dpdk-dev] [PATCH 1/5] virtio: clean up space checks on xmit
Stephen Hemminger
stephen at networkplumber.org
Mon Oct 19 07:16:08 CEST 2015
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 at networkplumber.org>
---
drivers/net/virtio/virtio_rxtx.c | 66 ++++++++++++++++------------------------
1 file changed, 27 insertions(+), 39 deletions(-)
diff --git a/drivers/net/virtio/virtio_rxtx.c b/drivers/net/virtio/virtio_rxtx.c
index c5b53bb..5b50ed0 100644
--- a/drivers/net/virtio/virtio_rxtx.c
+++ b/drivers/net/virtio/virtio_rxtx.c
@@ -745,7 +745,6 @@ 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;
@@ -759,57 +758,46 @@ 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;
+ for (nb_tx = 0; nb_tx < nb_pkts; nb_tx++) {
+ struct rte_mbuf *txm = tx_pkts[nb_tx];
+ int need = txm->nb_segs - txvq->vq_free_cnt + 1;
- while (nb_tx < nb_pkts) {
- /* Need one more descriptor for virtio header. */
- int need = tx_pkts[nb_tx]->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;
- }
+ need = txm->nb_segs - txvq->vq_free_cnt + 1;
+ if (unlikely(need > 0)) {
+ PMD_TX_LOG(ERR,
+ "No free tx descriptors to transmit");
+ break;
}
+ }
- /* Enqueue Packet buffers */
- error = virtqueue_enqueue_xmit(txvq, txm);
+ /* Do VLAN tag insertion */
+ if (unlikely(txm->ol_flags & PKT_TX_VLAN_PKT)) {
+ error = rte_vlan_insert(&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;
+ rte_pktmbuf_free(txm);
+ continue;
}
- nb_tx++;
- txvq->bytes += txm->pkt_len;
- } else {
- PMD_TX_LOG(ERR, "No free tx descriptors to transmit");
+ }
+
+ /* 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;
}
txvq->packets += nb_tx;
--
2.1.4
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