Stefano Garzarella
2022-Jun-21 16:08 UTC
[PATCH 2/3] vdpa_sim_blk: limit the number of request handled per batch
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 P?rez <eperezma at redhat.com>
Signed-off-by: Stefano Garzarella <sgarzare at redhat.com>
---
drivers/vdpa/vdpa_sim/vdpa_sim_blk.c | 15 ++++++++++++++-
1 file changed, 14 insertions(+), 1 deletion(-)
diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim_blk.c
b/drivers/vdpa/vdpa_sim/vdpa_sim_blk.c
index a83a5c76f620..ac86478845b6 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);
@@ -206,11 +207,15 @@ 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];
+ bool vq_work = true;
+ int reqs = 0;
if (!vq->ready)
continue;
- while (vdpasim_blk_handle_req(vdpasim, vq)) {
+ while (vq_work) {
+ vq_work = vdpasim_blk_handle_req(vdpasim, vq);
+
/* Make sure used is visible before rasing the interrupt. */
smp_wmb();
@@ -218,10 +223,18 @@ 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) {
+ vq_work = false;
+ reschedule = true;
+ }
}
}
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
Jason Wang
2022-Jun-23 03:50 UTC
[PATCH 2/3] vdpa_sim_blk: limit the number of request handled per batch
On Wed, Jun 22, 2022 at 12:09 AM Stefano Garzarella <sgarzare at redhat.com> 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 P?rez <eperezma at redhat.com> > Signed-off-by: Stefano Garzarella <sgarzare at redhat.com> > --- > drivers/vdpa/vdpa_sim/vdpa_sim_blk.c | 15 ++++++++++++++- > 1 file changed, 14 insertions(+), 1 deletion(-) > > diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim_blk.c b/drivers/vdpa/vdpa_sim/vdpa_sim_blk.c > index a83a5c76f620..ac86478845b6 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); > @@ -206,11 +207,15 @@ 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]; > + bool vq_work = true; > + int reqs = 0; > > if (!vq->ready) > continue; > > - while (vdpasim_blk_handle_req(vdpasim, vq)) { > + while (vq_work) { > + vq_work = vdpasim_blk_handle_req(vdpasim, vq); > +Is it better to check and exit the loop early here? Thanks> /* Make sure used is visible before rasing the interrupt. */ > smp_wmb(); > > @@ -218,10 +223,18 @@ 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) { > + vq_work = false; > + reschedule = true; > + } > } > } > 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 >