vhost: introduce last available index for dequeue

[dpdk.git] / lib / librte_vhost / virtio_net.c

diff --git a/lib/librte_vhost/virtio_net.c b/lib/librte_vhost/virtio_net.c
index a59c39b..70301a5 100644 (file)
--- a/lib/librte_vhost/virtio_net.c
+++ b/lib/librte_vhost/virtio_net.c
@@ -851,16 +851,17 @@ rte_vhost_dequeue_burst(int vid, uint16_t queue_id,
                }
        }
 
-       avail_idx =  *((volatile uint16_t *)&vq->avail->idx);
-       free_entries = avail_idx - vq->last_used_idx;
+       free_entries = *((volatile uint16_t *)&vq->avail->idx) -
+                       vq->last_avail_idx;
        if (free_entries == 0)
                goto out;
 
        LOG_DEBUG(VHOST_DATA, "(%d) %s\n", dev->vid, __func__);
 
-       /* Prefetch available ring to retrieve head indexes. */
-       used_idx = vq->last_used_idx & (vq->size - 1);
-       rte_prefetch0(&vq->avail->ring[used_idx]);
+       /* Prefetch available and used ring */
+       avail_idx = vq->last_avail_idx & (vq->size - 1);
+       used_idx  = vq->last_used_idx  & (vq->size - 1);
+       rte_prefetch0(&vq->avail->ring[avail_idx]);
        rte_prefetch0(&vq->used->ring[used_idx]);
 
        count = RTE_MIN(count, MAX_PKT_BURST);
@@ -870,8 +871,9 @@ rte_vhost_dequeue_burst(int vid, uint16_t queue_id,
 
        /* Retrieve all of the head indexes first to avoid caching issues. */
        for (i = 0; i < count; i++) {
-               used_idx = (vq->last_used_idx + i) & (vq->size - 1);
-               desc_indexes[i] = vq->avail->ring[used_idx];
+               avail_idx = (vq->last_avail_idx + i) & (vq->size - 1);
+               used_idx  = (vq->last_used_idx  + i) & (vq->size - 1);
+               desc_indexes[i] = vq->avail->ring[avail_idx];
 
                vq->used->ring[used_idx].id  = desc_indexes[i];
                vq->used->ring[used_idx].len = 0;
@@ -921,7 +923,8 @@ rte_vhost_dequeue_burst(int vid, uint16_t queue_id,
        rte_smp_wmb();
        rte_smp_rmb();
        vq->used->idx += i;
-       vq->last_used_idx += i;
+       vq->last_avail_idx += i;
+       vq->last_used_idx  += i;
        vhost_log_used_vring(dev, vq, offsetof(struct vring_used, idx),
                        sizeof(vq->used->idx));