vhost: prefetch first descriptor in dequeue path

Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
Acked-by: Tiwei Bie <tiwei.bie@intel.com>

diff --git a/lib/librte_vhost/virtio_net.c b/lib/librte_vhost/virtio_net.c
index 2cfd858..2662a1d 100644 (file)
--- a/lib/librte_vhost/virtio_net.c
+++ b/lib/librte_vhost/virtio_net.c
@@ -1083,6 +1083,8 @@ rte_vhost_dequeue_burst(int vid, uint16_t queue_id,
                vq->shadow_used_idx = 0;
        }
 
+       rte_prefetch0(&vq->avail->ring[vq->last_avail_idx & (vq->size - 1)]);
+
        /*
         * Construct a RARP broadcast packet, and inject it to the "pkts"
         * array, to looks like that guest actually send such packet.