vhost: fix unnecessary dirty page logging

The dirty page logging is only required in vhost enqueue direction for
live migration. This patch removes the unnecessary dirty page logging
in vhost dequeue direction. Otherwise, it will result in a performance
drop. Some if-else judgements are also optimized to improve performance.

Fixes: 6d823bb302c7 ("vhost: prepare sync for descriptor to mbuf refactoring")
Fixes: b6eee3e83402 ("vhost: fix sync dequeue offload")
Signed-off-by: Xuan Ding <xuan.ding@intel.com>
Reviewed-by: Jiayu Hu <jiayu.hu@intel.com>
Reviewed-by: Chenbo Xia <chenbo.xia@intel.com>
Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>
Tested-by: Xingguang He <xingguang.he@intel.com>

diff --git a/lib/vhost/virtio_net.c b/lib/vhost/virtio_net.c
index e842c35fef0febd1af492448b86b928bd067b7ae..12b7fbe7f9d8e3a10b9224853c70708399fd0ec7 100644 (file)
--- a/lib/vhost/virtio_net.c
+++ b/lib/vhost/virtio_net.c
@@ -1113,27 +1113,27 @@ sync_fill_seg(struct virtio_net *dev, struct vhost_virtqueue *vq,
                        rte_memcpy((void *)((uintptr_t)(buf_addr)),
                                rte_pktmbuf_mtod_offset(m, void *, mbuf_offset),
                                cpy_len);
+                       vhost_log_cache_write_iova(dev, vq, buf_iova, cpy_len);
+                       PRINT_PACKET(dev, (uintptr_t)(buf_addr), cpy_len, 0);
                } else {
                        rte_memcpy(rte_pktmbuf_mtod_offset(m, void *, mbuf_offset),
                                (void *)((uintptr_t)(buf_addr)),
                                cpy_len);
                }
-               vhost_log_cache_write_iova(dev, vq, buf_iova, cpy_len);
-               PRINT_PACKET(dev, (uintptr_t)(buf_addr), cpy_len, 0);
        } else {
                if (to_desc) {
                        batch_copy[vq->batch_copy_nb_elems].dst =
                                (void *)((uintptr_t)(buf_addr));
                        batch_copy[vq->batch_copy_nb_elems].src =
                                rte_pktmbuf_mtod_offset(m, void *, mbuf_offset);
+                       batch_copy[vq->batch_copy_nb_elems].log_addr = buf_iova;
+                       batch_copy[vq->batch_copy_nb_elems].len = cpy_len;
                } else {
                        batch_copy[vq->batch_copy_nb_elems].dst =
                                rte_pktmbuf_mtod_offset(m, void *, mbuf_offset);
                        batch_copy[vq->batch_copy_nb_elems].src =
                                (void *)((uintptr_t)(buf_addr));
                }
-               batch_copy[vq->batch_copy_nb_elems].log_addr = buf_iova;
-               batch_copy[vq->batch_copy_nb_elems].len = cpy_len;
                vq->batch_copy_nb_elems++;
        }
 }
@@ -2739,18 +2739,14 @@ desc_to_mbuf(struct virtio_net *dev, struct vhost_virtqueue *vq,
                        if (async_fill_seg(dev, vq, cur, mbuf_offset,
                                           buf_iova + buf_offset, cpy_len, false) < 0)
                                goto error;
+               } else if (likely(hdr && cur == m)) {
+                       rte_memcpy(rte_pktmbuf_mtod_offset(cur, void *, mbuf_offset),
+                               (void *)((uintptr_t)(buf_addr + buf_offset)),
+                               cpy_len);
                } else {
-                       if (hdr && cur == m) {
-                               rte_memcpy(rte_pktmbuf_mtod_offset(cur, void *, mbuf_offset),
-                                       (void *)((uintptr_t)(buf_addr + buf_offset)),
-                                       cpy_len);
-                               vhost_log_cache_write_iova(dev, vq, buf_iova + buf_offset, cpy_len);
-                               PRINT_PACKET(dev, (uintptr_t)(buf_addr + buf_offset), cpy_len, 0);
-                       } else {
-                               sync_fill_seg(dev, vq, cur, mbuf_offset,
-                                       buf_addr + buf_offset,
-                                       buf_iova + buf_offset, cpy_len, false);
-                       }
+                       sync_fill_seg(dev, vq, cur, mbuf_offset,
+                                     buf_addr + buf_offset,
+                                     buf_iova + buf_offset, cpy_len, false);
                }
 
                mbuf_avail  -= cpy_len;
@@ -2804,9 +2800,8 @@ desc_to_mbuf(struct virtio_net *dev, struct vhost_virtqueue *vq,
                async_iter_finalize(async);
                if (hdr)
                        pkts_info[slot_idx].nethdr = *hdr;
-       } else {
-               if (hdr)
-                       vhost_dequeue_offload(dev, hdr, m, legacy_ol_flags);
+       } else if (hdr) {
+               vhost_dequeue_offload(dev, hdr, m, legacy_ol_flags);
        }
 
        return 0;