On Thu, Jun 30, 2022 at 11:32 PM Stefano Garzarella <sgarzare@xxxxxxxxxx> wrote:
>
> Limit the number of requests (4 per queue as for vdpa_sim_net) handled
> in a batch to prevent the worker from using the CPU for too long.
>
> Suggested-by: Eugenio Pérez <eperezma@xxxxxxxxxx>
> Signed-off-by: Stefano Garzarella <sgarzare@xxxxxxxxxx>
Acked-by: Jason Wang <jasowang@xxxxxxxxxx>
> ---
> v2:
> - restored previous behaviour, exiting the loop immediately if the
> request is malformed [Jason]
> ---
> drivers/vdpa/vdpa_sim/vdpa_sim_blk.c | 10 ++++++++++
> 1 file changed, 10 insertions(+)
>
> diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim_blk.c b/drivers/vdpa/vdpa_sim/vdpa_sim_blk.c
> index a83a5c76f620..b2d75efec63a 100644
> --- a/drivers/vdpa/vdpa_sim/vdpa_sim_blk.c
> +++ b/drivers/vdpa/vdpa_sim/vdpa_sim_blk.c
> @@ -197,6 +197,7 @@ static bool vdpasim_blk_handle_req(struct vdpasim *vdpasim,
> static void vdpasim_blk_work(struct work_struct *work)
> {
> struct vdpasim *vdpasim = container_of(work, struct vdpasim, work);
> + bool reschedule = false;
> int i;
>
> spin_lock(&vdpasim->lock);
> @@ -206,6 +207,7 @@ static void vdpasim_blk_work(struct work_struct *work)
>
> for (i = 0; i < VDPASIM_BLK_VQ_NUM; i++) {
> struct vdpasim_virtqueue *vq = &vdpasim->vqs[i];
> + int reqs = 0;
>
> if (!vq->ready)
> continue;
> @@ -218,10 +220,18 @@ static void vdpasim_blk_work(struct work_struct *work)
> if (vringh_need_notify_iotlb(&vq->vring) > 0)
> vringh_notify(&vq->vring);
> local_bh_enable();
> +
> + if (++reqs > 4) {
> + reschedule = true;
> + break;
> + }
> }
> }
> out:
> spin_unlock(&vdpasim->lock);
> +
> + if (reschedule)
> + schedule_work(&vdpasim->work);
> }
>
> static void vdpasim_blk_get_config(struct vdpasim *vdpasim, void *config)
> --
> 2.36.1
>
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