[v2,7/7] vhost: improve prefetching in enqueue path
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Commit Message
This is an optimization to prefetch next buffer while the
current one is being processed.
Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
---
lib/librte_vhost/virtio_net.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)
@@ -387,6 +387,9 @@ copy_mbuf_to_desc(struct virtio_net *dev, struct vhost_virtqueue *vq,
buf_iova = buf_vec[vec_idx].buf_iova;
buf_len = buf_vec[vec_idx].buf_len;
+ if (nr_vec > 1)
+ rte_prefetch0((void *)(uintptr_t)buf_vec[1].buf_addr);
+
if (unlikely(buf_len < dev->vhost_hlen && nr_vec <= 1)) {
error = -1;
goto out;
@@ -398,7 +401,6 @@ copy_mbuf_to_desc(struct virtio_net *dev, struct vhost_virtqueue *vq,
hdr = &tmp_hdr;
else
hdr = (struct virtio_net_hdr_mrg_rxbuf *)(uintptr_t)hdr_addr;
- rte_prefetch0((void *)(uintptr_t)hdr_addr);
VHOST_LOG_DEBUG(VHOST_DATA, "(%d) RX: num merge buffers %d\n",
dev->vid, num_buffers);
@@ -430,8 +432,10 @@ copy_mbuf_to_desc(struct virtio_net *dev, struct vhost_virtqueue *vq,
buf_iova = buf_vec[vec_idx].buf_iova;
buf_len = buf_vec[vec_idx].buf_len;
- /* Prefetch buffer address. */
- rte_prefetch0((void *)(uintptr_t)buf_addr);
+ /* Prefetch next buffer address. */
+ if (vec_idx + 1 < nr_vec)
+ rte_prefetch0((void *)(uintptr_t)
+ buf_vec[vec_idx + 1].buf_addr);
buf_offset = 0;
buf_avail = buf_len;
}
@@ -573,6 +577,8 @@ virtio_dev_rx(struct virtio_net *dev, uint16_t queue_id,
break;
}
+ rte_prefetch0((void *)(uintptr_t)buf_vec[0].buf_addr);
+
VHOST_LOG_DEBUG(VHOST_DATA, "(%d) current index %d | end index %d\n",
dev->vid, vq->last_avail_idx,
vq->last_avail_idx + num_buffers);