[dpdk-dev] [PATCH] net/virtio: get all pending Rx packets in altivec vectorized paths

[David Christensen]

The loop to read packets does not take all packets as the number of
available packets (nb_used) is decremented in the loop.
Take all available packets provides a performance improvement of 3%.

Fixes: fc3d66212fed ("virtio: add vector Rx")
Cc: stable at dpdk.org
Cc: thibaut.collet at 6wind.com
Cc: maxime.coquelin at redhat.com
Cc: tiwei.bie at intel.com
Cc: zhihong.wang at intel.com
Cc: jerinj at marvell.com
Cc: gavin.hu at arm.com

Signed-off-by: David Christensen <drc at linux.vnet.ibm.com>
---
 drivers/net/virtio/virtio_rxtx_simple_altivec.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/net/virtio/virtio_rxtx_simple_altivec.c b/drivers/net/virtio/virtio_rxtx_simple_altivec.c
index f856396ab..47225f412 100644
--- a/drivers/net/virtio/virtio_rxtx_simple_altivec.c
+++ b/drivers/net/virtio/virtio_rxtx_simple_altivec.c
@@ -44,7 +44,7 @@ virtio_recv_pkts_vec(void *rx_queue, struct rte_mbuf **rx_pkts,
 	struct virtnet_rx *rxvq = rx_queue;
 	struct virtqueue *vq = rxvq->vq;
 	struct virtio_hw *hw = vq->hw;
-	uint16_t nb_used;
+	uint16_t nb_used, nb_total;
 	uint16_t desc_idx;
 	struct vring_used_elem *rused;
 	struct rte_mbuf **sw_ring;
@@ -109,9 +109,10 @@ virtio_recv_pkts_vec(void *rx_queue, struct rte_mbuf **rx_pkts,
 			virtqueue_notify(vq);
 	}
 
+	nb_total = nb_used;
 	ref_rx_pkts = rx_pkts;
 	for (nb_pkts_received = 0;
-		nb_pkts_received < nb_used;) {
+		nb_pkts_received < nb_total;) {
 		vector unsigned char desc[RTE_VIRTIO_DESC_PER_LOOP / 2];
 		vector unsigned char mbp[RTE_VIRTIO_DESC_PER_LOOP / 2];
 		vector unsigned char pkt_mb[RTE_VIRTIO_DESC_PER_LOOP];
-- 
2.18.1