This patch enables batch update of the used ring for better efficiency.
Signed-off-by: Zhihong Wang <zhihong.wang at intel.com>
---
lib/librte_vhost/vhost-net.h | 4 +++
lib/librte_vhost/vhost_rxtx.c | 68 +++++++++++++++++++++++++++++++++----------
lib/librte_vhost/virtio-net.c | 15 ++++++++--
3 files changed, 68 insertions(+), 19 deletions(-)
diff --git a/lib/librte_vhost/vhost-net.h b/lib/librte_vhost/vhost-net.h
index 51fdf3d..a15182c 100644
--- a/lib/librte_vhost/vhost-net.h
+++ b/lib/librte_vhost/vhost-net.h
@@ -85,6 +85,10 @@ struct vhost_virtqueue {
/* Physical address of used ring, for logging */
uint64_t log_guest_addr;
+
+ /* Shadow used ring for performance */
+ struct vring_used_elem *shadow_used_ring;
+ uint32_t shadow_used_idx;
} __rte_cache_aligned;
/* Old kernels have no such macro defined */
diff --git a/lib/librte_vhost/vhost_rxtx.c b/lib/librte_vhost/vhost_rxtx.c
index 7db83d0..60d63d3 100644
--- a/lib/librte_vhost/vhost_rxtx.c
+++ b/lib/librte_vhost/vhost_rxtx.c
@@ -155,7 +155,6 @@ enqueue_packet(struct virtio_net *dev, struct
vhost_virtqueue *vq,
uint32_t mbuf_len_left = 0;
uint32_t copy_len = 0;
uint32_t extra_buffers = 0;
- uint32_t used_idx_round = 0;
/* start with the first mbuf of the packet */
mbuf_len = rte_pktmbuf_data_len(mbuf);
@@ -207,17 +206,11 @@ enqueue_packet(struct virtio_net *dev, struct
vhost_virtqueue *vq,
goto rollback;
} else if (is_mrg_rxbuf) {
/* start with the next desc chain */
- used_idx_round = vq->last_used_idx
- & (vq->size - 1);
- vq->used->ring[used_idx_round].id =
+ vq->shadow_used_ring[vq->shadow_used_idx].id =
desc_chain_head;
- vq->used->ring[used_idx_round].len =
+ vq->shadow_used_ring[vq->shadow_used_idx].len =
desc_chain_len;
- vhost_log_used_vring(dev, vq,
- offsetof(struct vring_used,
- ring[used_idx_round]),
- sizeof(vq->used->ring[
- used_idx_round]));
+ vq->shadow_used_idx++;
vq->last_used_idx++;
extra_buffers++;
virtio_hdr->num_buffers++;
@@ -255,12 +248,9 @@ enqueue_packet(struct virtio_net *dev, struct
vhost_virtqueue *vq,
desc_chain_len += copy_len;
}
- used_idx_round = vq->last_used_idx & (vq->size - 1);
- vq->used->ring[used_idx_round].id = desc_chain_head;
- vq->used->ring[used_idx_round].len = desc_chain_len;
- vhost_log_used_vring(dev, vq,
- offsetof(struct vring_used, ring[used_idx_round]),
- sizeof(vq->used->ring[used_idx_round]));
+ vq->shadow_used_ring[vq->shadow_used_idx].id = desc_chain_head;
+ vq->shadow_used_ring[vq->shadow_used_idx].len = desc_chain_len;
+ vq->shadow_used_idx++;
vq->last_used_idx++;
return 0;
@@ -275,6 +265,45 @@ error:
}
static inline void __attribute__((always_inline))
+update_used_ring(struct virtio_net *dev, struct vhost_virtqueue *vq,
+ uint32_t used_idx_start)
+{
+ if (used_idx_start + vq->shadow_used_idx < vq->size) {
+ rte_memcpy(&vq->used->ring[used_idx_start],
+ &vq->shadow_used_ring[0],
+ vq->shadow_used_idx *
+ sizeof(struct vring_used_elem));
+ vhost_log_used_vring(dev, vq,
+ offsetof(struct vring_used,
+ ring[used_idx_start]),
+ vq->shadow_used_idx *
+ sizeof(struct vring_used_elem));
+ } else {
+ uint32_t part_1 = vq->size - used_idx_start;
+ uint32_t part_2 = vq->shadow_used_idx - part_1;
+
+ rte_memcpy(&vq->used->ring[used_idx_start],
+ &vq->shadow_used_ring[0],
+ part_1 *
+ sizeof(struct vring_used_elem));
+ vhost_log_used_vring(dev, vq,
+ offsetof(struct vring_used,
+ ring[used_idx_start]),
+ part_1 *
+ sizeof(struct vring_used_elem));
+ rte_memcpy(&vq->used->ring[0],
+ &vq->shadow_used_ring[part_1],
+ part_2 *
+ sizeof(struct vring_used_elem));
+ vhost_log_used_vring(dev, vq,
+ offsetof(struct vring_used,
+ ring[0]),
+ part_2 *
+ sizeof(struct vring_used_elem));
+ }
+}
+
+static inline void __attribute__((always_inline))
notify_guest(struct virtio_net *dev, struct vhost_virtqueue *vq)
{
rte_smp_wmb();
@@ -293,6 +322,7 @@ rte_vhost_enqueue_burst(int vid, uint16_t queue_id,
{
struct vhost_virtqueue *vq;
struct virtio_net *dev;
+ uint32_t used_idx_start = 0;
uint32_t pkt_idx = 0;
uint32_t pkt_left = 0;
uint32_t pkt_sent = 0;
@@ -322,6 +352,8 @@ rte_vhost_enqueue_burst(int vid, uint16_t queue_id,
/* start enqueuing packets 1 by 1 */
pkt_idx = 0;
pkt_left = count;
+ vq->shadow_used_idx = 0;
+ used_idx_start = vq->last_used_idx & (vq->size - 1);
avail_idx = *((volatile uint16_t *)&vq->avail->idx);
while (1) {
if (loop_check(vq, avail_idx, pkt_left))
@@ -336,6 +368,10 @@ rte_vhost_enqueue_burst(int vid, uint16_t queue_id,
pkt_left--;
}
+ /* batch update used ring for better performance */
+ if (likely(vq->shadow_used_idx > 0))
+ update_used_ring(dev, vq, used_idx_start);
+
/* update used idx and kick the guest if necessary */
if (pkt_sent)
notify_guest(dev, vq);
diff --git a/lib/librte_vhost/virtio-net.c b/lib/librte_vhost/virtio-net.c
index 1785695..87d09fa 100644
--- a/lib/librte_vhost/virtio-net.c
+++ b/lib/librte_vhost/virtio-net.c
@@ -152,10 +152,14 @@ cleanup_device(struct virtio_net *dev, int destroy)
static void
free_device(struct virtio_net *dev)
{
+ struct vhost_virtqueue *vq;
uint32_t i;
- for (i = 0; i < dev->virt_qp_nb; i++)
- rte_free(dev->virtqueue[i * VIRTIO_QNUM]);
+ for (i = 0; i < dev->virt_qp_nb; i++) {
+ vq = dev->virtqueue[i * VIRTIO_QNUM];
+ rte_free(vq->shadow_used_ring);
+ rte_free(vq);
+ }
rte_free(dev);
}
@@ -418,13 +422,18 @@ int
vhost_set_vring_num(int vid, struct vhost_vring_state *state)
{
struct virtio_net *dev;
+ struct vhost_virtqueue *vq;
dev = get_device(vid);
if (dev == NULL)
return -1;
/* State->index refers to the queue index. The txq is 1, rxq is 0. */
- dev->virtqueue[state->index]->size = state->num;
+ vq = dev->virtqueue[state->index];
+ vq->size = state->num;
+ vq->shadow_used_ring = rte_malloc("",
+ vq->size * sizeof(struct vring_used_elem),
+ RTE_CACHE_LINE_SIZE);
return 0;
}
--
2.7.4
