virtio_ring: remove unnecessary to_vvq call in virtqueue_disable_cb_packed

[PATCH] virtio_ring: remove unnecessary to_vvq call in virtqueue_disable_cb_packed

Posted by Deming Wang 3 years, 10 months ago

It passes '_vq' to virtqueue_use_indirect(), which still calls
to_vvq to get 'vq', let's directly pass 'vq'. It can avoid
unnecessary call of to_vvq in hot path.

Signed-off-by: Deming Wang <wangdeming@inspur.com>
---
 drivers/virtio/virtio_ring.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 13a7348cedff..af2b7785ed77 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -1475,10 +1475,8 @@ static void *virtqueue_get_buf_ctx_packed(struct virtqueue *_vq,
 	return ret;
 }
 
-static void virtqueue_disable_cb_packed(struct virtqueue *_vq)
+static void virtqueue_disable_cb_packed(struct vring_virtqueue *vq)
 {
-	struct vring_virtqueue *vq = to_vvq(_vq);
-
 	if (vq->packed.event_flags_shadow != VRING_PACKED_EVENT_FLAG_DISABLE) {
 		vq->packed.event_flags_shadow = VRING_PACKED_EVENT_FLAG_DISABLE;
 		vq->packed.vring.driver->flags =
@@ -2007,7 +2005,7 @@ void virtqueue_disable_cb(struct virtqueue *_vq)
 		return;
 
 	if (vq->packed_ring)
-		virtqueue_disable_cb_packed(_vq);
+		virtqueue_disable_cb_packed(vq);
 	else
 		virtqueue_disable_cb_split(_vq);
 }
-- 
2.27.0

Re: [PATCH] virtio_ring: remove unnecessary to_vvq call in virtqueue_disable_cb_packed

Posted by Michael S. Tsirkin 3 years, 10 months ago

On Wed, Jun 22, 2022 at 03:50:52AM -0400, Deming Wang wrote:
> It passes '_vq' to virtqueue_use_indirect(), which still calls
> to_vvq to get 'vq', let's directly pass 'vq'. It can avoid
> unnecessary call of to_vvq in hot path.
> 
> Signed-off-by: Deming Wang <wangdeming@inspur.com>

I do not see the point of any of these patches. Sorry.
If this is supposed to be an optimization, post some numbers pls.


> ---
>  drivers/virtio/virtio_ring.c | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> index 13a7348cedff..af2b7785ed77 100644
> --- a/drivers/virtio/virtio_ring.c
> +++ b/drivers/virtio/virtio_ring.c
> @@ -1475,10 +1475,8 @@ static void *virtqueue_get_buf_ctx_packed(struct virtqueue *_vq,
>  	return ret;
>  }
>  
> -static void virtqueue_disable_cb_packed(struct virtqueue *_vq)
> +static void virtqueue_disable_cb_packed(struct vring_virtqueue *vq)
>  {
> -	struct vring_virtqueue *vq = to_vvq(_vq);
> -
>  	if (vq->packed.event_flags_shadow != VRING_PACKED_EVENT_FLAG_DISABLE) {
>  		vq->packed.event_flags_shadow = VRING_PACKED_EVENT_FLAG_DISABLE;
>  		vq->packed.vring.driver->flags =
> @@ -2007,7 +2005,7 @@ void virtqueue_disable_cb(struct virtqueue *_vq)
>  		return;
>  
>  	if (vq->packed_ring)
> -		virtqueue_disable_cb_packed(_vq);
> +		virtqueue_disable_cb_packed(vq);
>  	else
>  		virtqueue_disable_cb_split(_vq);
>  }
> -- 
> 2.27.0

答复: [PATCH] virtio_ring: remove unnecessary to_vvq call in virtqueue_disable_cb_packed

Posted by tomorrow Wang (王德明) 3 years, 10 months ago

Hi，
  The  35c51e093d956f6d058e193711c8d424817a44a9 patch has  maked  a similar
change
  
> Re: [PATCH] virtio_ring: remove unnecessary to_vvq call in
> virtqueue_disable_cb_packed
> 
> On Wed, Jun 22, 2022 at 03:50:52AM -0400, Deming Wang wrote:
> > It passes '_vq' to virtqueue_use_indirect(), which still calls to_vvq
> > to get 'vq', let's directly pass 'vq'. It can avoid unnecessary call
> > of to_vvq in hot path.
> >
> > Signed-off-by: Deming Wang <wangdeming@inspur.com>
> 
> I do not see the point of any of these patches. Sorry.
> If this is supposed to be an optimization, post some numbers pls.
> 
> 
> > ---
> >  drivers/virtio/virtio_ring.c | 6 ++----
> >  1 file changed, 2 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/virtio/virtio_ring.c
> > b/drivers/virtio/virtio_ring.c index 13a7348cedff..af2b7785ed77 100644
> > --- a/drivers/virtio/virtio_ring.c
> > +++ b/drivers/virtio/virtio_ring.c
> > @@ -1475,10 +1475,8 @@ static void
> *virtqueue_get_buf_ctx_packed(struct virtqueue *_vq,
> >  	return ret;
> >  }
> >
> > -static void virtqueue_disable_cb_packed(struct virtqueue *_vq)
> > +static void virtqueue_disable_cb_packed(struct vring_virtqueue *vq)
> >  {
> > -	struct vring_virtqueue *vq = to_vvq(_vq);
> > -
> >  	if (vq->packed.event_flags_shadow !=
> VRING_PACKED_EVENT_FLAG_DISABLE) {
> >  		vq->packed.event_flags_shadow =
> VRING_PACKED_EVENT_FLAG_DISABLE;
> >  		vq->packed.vring.driver->flags =
> > @@ -2007,7 +2005,7 @@ void virtqueue_disable_cb(struct virtqueue *_vq)
> >  		return;
> >
> >  	if (vq->packed_ring)
> > -		virtqueue_disable_cb_packed(_vq);
> > +		virtqueue_disable_cb_packed(vq);
> >  	else
> >  		virtqueue_disable_cb_split(_vq);
> >  }
> > --
> > 2.27.0