[dpdk-dev] [RFC 22/29] vhost: don't copy descs during Rx

[Tiwei Bie]

Signed-off-by: Tiwei Bie <tiwei....@intel.com>
---
 lib/librte_vhost/virtio_net.c | 35 ++++++++++-------------------------
 1 file changed, 10 insertions(+), 25 deletions(-)

diff --git a/lib/librte_vhost/virtio_net.c b/lib/librte_vhost/virtio_net.c
index 7a978b9..c14582b 100644
--- a/lib/librte_vhost/virtio_net.c
+++ b/lib/librte_vhost/virtio_net.c
@@ -1247,35 +1247,18 @@ vhost_dequeue_burst_1_1(struct virtio_net *dev, struct 
vhost_virtqueue *vq,
                        uint16_t count)
 {
        uint16_t i;
-       uint16_t idx;
        struct vring_desc_1_1 *desc = vq->desc_1_1;
        uint16_t head_idx = vq->last_used_idx;
-       struct vring_desc_1_1 desc_cached[64];
-       uint16_t desc_idx = 0;
+       uint16_t desc_idx;
 
-       idx = vq->last_used_idx & (vq->size - 1);
-       if (!(desc[idx].flags & DESC_HW))
+       desc_idx = vq->last_used_idx;
+       if (!(desc[desc_idx & (vq->size - 1)].flags & DESC_HW))
                return 0;
 
        count = RTE_MIN(MAX_PKT_BURST, count);
 
-       {
-               uint16_t size = vq->size - idx;
-               if (size >= 64)
-                       rte_memcpy(&desc_cached[0],    &desc[idx], 64 * 
sizeof(struct vring_desc_1_1));
-               else {
-                       rte_memcpy(&desc_cached[0],    &desc[idx], size * 
sizeof(struct vring_desc_1_1));
-                       rte_memcpy(&desc_cached[size], &desc[0],   (64 - size) 
* sizeof(struct vring_desc_1_1));
-               }
-       }
-
-       //for (i = 0; i < 64; i++) {
-       //      idx = (vq->last_used_idx + i) & (vq->size - 1);
-       //      desc_cached[i] = desc[idx];
-       //}
-
        for (i = 0; i < count; i++) {
-               if (!(desc_cached[desc_idx].flags & DESC_HW))
+               if (!(desc[desc_idx & (vq->size - 1)].flags & DESC_HW))
                        break;
 
                pkts[i] = rte_pktmbuf_alloc(mbuf_pool);
@@ -1285,13 +1268,15 @@ vhost_dequeue_burst_1_1(struct virtio_net *dev, struct 
vhost_virtqueue *vq,
                        break;
                }
 
-               dequeue_desc(dev, vq, mbuf_pool, pkts[i], desc_cached, 
&desc_idx);
+               dequeue_desc(dev, vq, mbuf_pool, pkts[i], desc, &desc_idx);
        }
 
-       vq->last_used_idx += desc_idx;
+       vq->last_used_idx = desc_idx;
        if (likely(i)) {
-               for (idx = 1; idx < (uint16_t)(vq->last_used_idx - head_idx); 
idx++) {
-                       desc[(idx + head_idx) & (vq->size - 1)].flags = 0;
+               for (desc_idx = 1;
+                    desc_idx < (uint16_t)(vq->last_used_idx - head_idx);
+                    desc_idx++) {
+                       desc[(desc_idx + head_idx) & (vq->size - 1)].flags = 0;
                }
                rte_smp_wmb();
                desc[head_idx & (vq->size - 1)].flags = 0;
-- 
2.7.4