[dpdk-dev] [PATCH 2/2] virtio: get all pending rx packets with vectorized functions

[Thierry Herbelot <thierry.herbelot@6wind.com>]

From: Thibaut Collet <thibaut.collet@6wind.com>

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@dpdk.org
Cc: maxime.coquelin@redhat.com
Cc: tiwei.bie@intel.com
Cc: zhihong.wang@intel.com
Cc: jerinj@marvell.com
Cc: gavin.hu@arm.com

Signed-off-by: Thibaut Collet <thibaut.collet@6wind.com>
---
 drivers/net/virtio/virtio_rxtx_simple_neon.c | 5 +++--
 drivers/net/virtio/virtio_rxtx_simple_sse.c  | 5 +++--
 2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/net/virtio/virtio_rxtx_simple_neon.c b/drivers/net/virtio/virtio_rxtx_simple_neon.c
index 70e89fc428e0..992e71f010eb 100644
--- a/drivers/net/virtio/virtio_rxtx_simple_neon.c
+++ b/drivers/net/virtio/virtio_rxtx_simple_neon.c
@@ -42,7 +42,7 @@ 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;
@@ -106,9 +106,10 @@ 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;) {
 		uint64x2_t desc[RTE_VIRTIO_DESC_PER_LOOP / 2];
 		uint64x2_t mbp[RTE_VIRTIO_DESC_PER_LOOP / 2];
 		uint64x2_t pkt_mb[RTE_VIRTIO_DESC_PER_LOOP];
diff --git a/drivers/net/virtio/virtio_rxtx_simple_sse.c b/drivers/net/virtio/virtio_rxtx_simple_sse.c
index cb1610e71563..f9ec4ae69986 100644
--- a/drivers/net/virtio/virtio_rxtx_simple_sse.c
+++ b/drivers/net/virtio/virtio_rxtx_simple_sse.c
@@ -43,7 +43,7 @@ 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;
@@ -108,9 +108,10 @@ 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;) {
 		__m128i desc[RTE_VIRTIO_DESC_PER_LOOP / 2];
 		__m128i mbp[RTE_VIRTIO_DESC_PER_LOOP / 2];
 		__m128i pkt_mb[RTE_VIRTIO_DESC_PER_LOOP];
-- 
2.20.1