[dpdk-dev] [PATCH v3 4/5] vhost: batch update used ring
On Fri, Aug 19, 2016 at 01:43:49AM -0400, Zhihong Wang wrote:
> This patch enables batch update of the used ring for better efficiency.
>
> Signed-off-by: Zhihong Wang
...
> 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);
Few notes here:
- I think the typical way to not specific a string type is using NULL,
but not "".
- You should check the return value of rte_malloc: it could fail.
- Note that free_device() is invoked only when the vhost-user connection
is broken (say the guest is halt). However, vhost_set_vring_num() could
be invoked many times for a connection, say when you restart testpmd
many times. This would lead to memory leak.
The right way is to free it on get_vring_base().
--yliu
[dpdk-dev] [PATCH v3 4/5] vhost: batch update used ring
> -Original Message-
> From: Yuanhan Liu [mailto:yuanhan.liu at linux.intel.com]
> Sent: Thursday, August 25, 2016 11:48 AM
> To: Wang, Zhihong
> Cc: dev at dpdk.org; maxime.coquelin at redhat.com
> Subject: Re: [PATCH v3 4/5] vhost: batch update used ring
>
> On Fri, Aug 19, 2016 at 01:43:49AM -0400, Zhihong Wang wrote:
> > This patch enables batch update of the used ring for better efficiency.
> >
> > Signed-off-by: Zhihong Wang
> ...
> > 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);
>
> Few notes here:
>
> - I think the typical way to not specific a string type is using NULL,
> but not "".
>
> - You should check the return value of rte_malloc: it could fail.
>
> - Note that free_device() is invoked only when the vhost-user connection
> is broken (say the guest is halt). However, vhost_set_vring_num() could
> be invoked many times for a connection, say when you restart testpmd
> many times. This would lead to memory leak.
>
> The right way is to free it on get_vring_base().
Good catch! Thanks.
>
> --yliu
[dpdk-dev] [PATCH v3 4/5] vhost: batch update used ring
This patch enables batch update of the used ring for better efficiency.
Signed-off-by: Zhihong Wang
---
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_tlog_guest_addr;
+
+ /* Shadow used ring for performance */
+ struct vring_used_elem *shadow_used_ring;
+ uint32_tshadow_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 7523b2d..c4abaf1 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_avail = 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);
@@ -203,17 +202,11 @@ 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++;
@@ -248,12 +241,9 @@ 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;
@@ -268,6 +258,45 @@ 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(>used->ring[used_idx_start],
+ >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(>used->ring[used_idx_start],
+ >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(>used->ring[0],
+ >shadow_used_ring[part_1],
+ part_2 *
+
