? 2022/9/1 13:54, Guo Zhi ??:> Vsock uses buffers in order, and for tx driver doesn't have to
> know the length of the buffer. So we can do a batch for vsock if
> in order negotiated, only write one used ring for a batch of buffers
>
> Signed-off-by: Guo Zhi <qtxuning1999 at sjtu.edu.cn>
> ---
> drivers/vhost/vsock.c | 12 ++++++++++--
> 1 file changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
> index 368330417bde..e08fbbb5439e 100644
> --- a/drivers/vhost/vsock.c
> +++ b/drivers/vhost/vsock.c
> @@ -497,7 +497,7 @@ static void vhost_vsock_handle_tx_kick(struct
vhost_work *work)
> struct vhost_vsock *vsock = container_of(vq->dev, struct vhost_vsock,
> dev);
> struct virtio_vsock_pkt *pkt;
> - int head, pkts = 0, total_len = 0;
> + int head, pkts = 0, total_len = 0, add = 0;
> unsigned int out, in;
> bool added = false;
>
> @@ -551,10 +551,18 @@ static void vhost_vsock_handle_tx_kick(struct
vhost_work *work)
> else
> virtio_transport_free_pkt(pkt);
>
> - vhost_add_used(vq, head, 0);
> + if (!vhost_has_feature(vq, VIRTIO_F_IN_ORDER)) {
> + vhost_add_used(vq, head, 0);
I'd do this step by step.
1) switch to use vhost_add_used_n() for vsock, less copy_to_user()
better performance
2) do in-order on top
> + } else {
> + vq->heads[add].id = head;
> + vq->heads[add++].len = 0;
How can we guarantee that we are in the boundary of the heads array?
Btw in the case of in-order we don't need to record the heads, instead
we just need to know the head of the last buffer, it reduces the stress
on the cache.
Thanks
> + }
> added = true;
> } while(likely(!vhost_exceeds_weight(vq, ++pkts, total_len)));
>
> + /* If in order feature negotiaged, we can do a batch to increase
performance */
> + if (vhost_has_feature(vq, VIRTIO_F_IN_ORDER) && added)
> + vhost_add_used_n(vq, vq->heads, add);
> no_more_replies:
> if (added)
> vhost_signal(&vsock->dev, vq);