On Wed, Jul 19, 2023 at 9:54 AM Hawkins Jiawei <yin31...@gmail.com> wrote:
>
The subject could be more explicit. What about "add count argument to
vhost_svq_poll"?
Apart from that:
Acked-by: Eugenio Pérez <epere...@redhat.com>
> Next patches in this series will no longer perform an
> immediate poll and check of the device's used buffers
> for each CVQ state load command. Instead, they will
> send CVQ state load commands in parallel by polling
> multiple pending buffers at once.
>
> To achieve this, this patch refactoring vhost_svq_poll()
> to accept a new argument `num`, which allows vhost_svq_poll()
> to wait for the device to use multiple elements,
> rather than polling for a single element.
>
> Signed-off-by: Hawkins Jiawei <yin31...@gmail.com>
> ---
> hw/virtio/vhost-shadow-virtqueue.c | 36 ++++++++++++++++++------------
> hw/virtio/vhost-shadow-virtqueue.h | 2 +-
> net/vhost-vdpa.c | 2 +-
> 3 files changed, 24 insertions(+), 16 deletions(-)
>
> diff --git a/hw/virtio/vhost-shadow-virtqueue.c
> b/hw/virtio/vhost-shadow-virtqueue.c
> index 49e5aed931..e731b1d2ea 100644
> --- a/hw/virtio/vhost-shadow-virtqueue.c
> +++ b/hw/virtio/vhost-shadow-virtqueue.c
> @@ -514,29 +514,37 @@ static void vhost_svq_flush(VhostShadowVirtqueue *svq,
> }
>
> /**
> - * Poll the SVQ for one device used buffer.
> + * Poll the SVQ to wait for the device to use the specified number
> + * of elements and return the total length written by the device.
> *
> * This function race with main event loop SVQ polling, so extra
> * synchronization is needed.
> *
> - * Return the length written by the device.
> + * @svq: The svq
> + * @num: The number of elements that need to be used
> */
> -size_t vhost_svq_poll(VhostShadowVirtqueue *svq)
> +size_t vhost_svq_poll(VhostShadowVirtqueue *svq, size_t num)
> {
> - int64_t start_us = g_get_monotonic_time();
> - uint32_t len = 0;
> + size_t len = 0;
> + uint32_t r;
>
> - do {
> - if (vhost_svq_more_used(svq)) {
> - break;
> - }
> + while (num--) {
> + int64_t start_us = g_get_monotonic_time();
>
> - if (unlikely(g_get_monotonic_time() - start_us > 10e6)) {
> - return 0;
> - }
> - } while (true);
> + do {
> + if (vhost_svq_more_used(svq)) {
> + break;
> + }
> +
> + if (unlikely(g_get_monotonic_time() - start_us > 10e6)) {
> + return len;
> + }
> + } while (true);
> +
> + vhost_svq_get_buf(svq, &r);
> + len += r;
> + }
>
> - vhost_svq_get_buf(svq, &len);
> return len;
> }
>
> diff --git a/hw/virtio/vhost-shadow-virtqueue.h
> b/hw/virtio/vhost-shadow-virtqueue.h
> index 6efe051a70..5bce67837b 100644
> --- a/hw/virtio/vhost-shadow-virtqueue.h
> +++ b/hw/virtio/vhost-shadow-virtqueue.h
> @@ -119,7 +119,7 @@ void vhost_svq_push_elem(VhostShadowVirtqueue *svq,
> int vhost_svq_add(VhostShadowVirtqueue *svq, const struct iovec *out_sg,
> size_t out_num, const struct iovec *in_sg, size_t in_num,
> VirtQueueElement *elem);
> -size_t vhost_svq_poll(VhostShadowVirtqueue *svq);
> +size_t vhost_svq_poll(VhostShadowVirtqueue *svq, size_t num);
>
> void vhost_svq_set_svq_kick_fd(VhostShadowVirtqueue *svq, int svq_kick_fd);
> void vhost_svq_set_svq_call_fd(VhostShadowVirtqueue *svq, int call_fd);
> diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c
> index dfd271c456..d1dd140bf6 100644
> --- a/net/vhost-vdpa.c
> +++ b/net/vhost-vdpa.c
> @@ -625,7 +625,7 @@ static ssize_t vhost_vdpa_net_cvq_add(VhostVDPAState *s,
> size_t out_len,
> * descriptor. Also, we need to take the answer before SVQ pulls by
> itself,
> * when BQL is released
> */
> - return vhost_svq_poll(svq);
> + return vhost_svq_poll(svq, 1);
> }
>
> static ssize_t vhost_vdpa_net_load_cmd(VhostVDPAState *s, uint8_t class,
> --
> 2.25.1
>
