[dpdk-dev] [RFC PATCH] avail idx update optimizations

[Huawei Xie]

eliminate unnecessary cache to cache transfer between virtio and vhost
core

---
 drivers/net/virtio/virtqueue.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/virtio/virtqueue.h b/drivers/net/virtio/virtqueue.h
index 4e9239e..8c46a83 100644
--- a/drivers/net/virtio/virtqueue.h
+++ b/drivers/net/virtio/virtqueue.h
@@ -302,7 +302,8 @@ vq_update_avail_ring(struct virtqueue *vq, uint16_t desc_idx)
 	 * descriptor.
 	 */
 	avail_idx = (uint16_t)(vq->vq_avail_idx & (vq->vq_nentries - 1));
-	vq->vq_ring.avail->ring[avail_idx] = desc_idx;
+	if (unlikely(vq->vq_ring.avail->ring[avail_idx] != desc_idx))
+		vq->vq_ring.avail->ring[avail_idx] = desc_idx;
 	vq->vq_avail_idx++;
 }
 
-- 
2.4.3