linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
* [PATCH v2] drm: make drm_file use keyed wakeups
@ 2020-04-24 16:26 Kenny Levinsen
  2020-04-28 15:14 ` Daniel Vetter
  2020-04-29 11:19 ` kl
  0 siblings, 2 replies; 4+ messages in thread
From: Kenny Levinsen @ 2020-04-24 16:26 UTC (permalink / raw)
  To: intel-gfx, dri-devel
  Cc: daniel, airlied, tzimmermann, mripard, maarten.lankhorst,
	linux-kernel, Kenny Levinsen

Some processes, such as systemd, are only polling for EPOLLERR|EPOLLHUP.
As drm_file uses unkeyed wakeups, such a poll can receive many spurious
wakeups from uninteresting events if, for example, the file description
is subscribed to vblank events. This is the case with systemd, as it
polls a file description from logind that is shared with the users'
compositor.

Use keyed wakeups to allow the wakeup target to more efficiently discard
these uninteresting events.

Signed-off-by: Kenny Levinsen <kl@kl.wtf>
---
 drivers/gpu/drm/drm_file.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/drm_file.c b/drivers/gpu/drm/drm_file.c
index c4c704e01961..ec25b3d979d9 100644
--- a/drivers/gpu/drm/drm_file.c
+++ b/drivers/gpu/drm/drm_file.c
@@ -608,7 +608,8 @@ ssize_t drm_read(struct file *filp, char __user *buffer,
 				file_priv->event_space -= length;
 				list_add(&e->link, &file_priv->event_list);
 				spin_unlock_irq(&dev->event_lock);
-				wake_up_interruptible(&file_priv->event_wait);
+				wake_up_interruptible_poll(&file_priv->event_wait,
+					EPOLLIN | EPOLLRDNORM);
 				break;
 			}
 
@@ -804,7 +805,8 @@ void drm_send_event_locked(struct drm_device *dev, struct drm_pending_event *e)
 	list_del(&e->pending_link);
 	list_add_tail(&e->link,
 		      &e->file_priv->event_list);
-	wake_up_interruptible(&e->file_priv->event_wait);
+	wake_up_interruptible_poll(&e->file_priv->event_wait,
+		EPOLLIN | EPOLLRDNORM);
 }
 EXPORT_SYMBOL(drm_send_event_locked);
 
-- 
2.26.1


^ permalink raw reply related	[flat|nested] 4+ messages in thread
* Re: [PATCH v2] drm: make drm_file use keyed wakeups
  2020-04-24 16:26 [PATCH v2] drm: make drm_file use keyed wakeups Kenny Levinsen
@ 2020-04-28 15:14 ` Daniel Vetter
  2020-04-29 11:19 ` kl
  1 sibling, 0 replies; 4+ messages in thread
From: Daniel Vetter @ 2020-04-28 15:14 UTC (permalink / raw)
  To: Kenny Levinsen
  Cc: intel-gfx, dri-devel, daniel, airlied, tzimmermann, mripard,
	maarten.lankhorst, linux-kernel

On Fri, Apr 24, 2020 at 06:26:15PM +0200, Kenny Levinsen wrote:
> Some processes, such as systemd, are only polling for EPOLLERR|EPOLLHUP.
> As drm_file uses unkeyed wakeups, such a poll can receive many spurious
> wakeups from uninteresting events if, for example, the file description
> is subscribed to vblank events. This is the case with systemd, as it
> polls a file description from logind that is shared with the users'
> compositor.
> 
> Use keyed wakeups to allow the wakeup target to more efficiently discard
> these uninteresting events.
> 
> Signed-off-by: Kenny Levinsen <kl@kl.wtf>

Hm I applied v1 and I'm not spotting what's different here, and there's no
changelog explaining what changed ...

Please send a fixup if there's anything important missing.
-Daniel

> ---
>  drivers/gpu/drm/drm_file.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_file.c b/drivers/gpu/drm/drm_file.c
> index c4c704e01961..ec25b3d979d9 100644
> --- a/drivers/gpu/drm/drm_file.c
> +++ b/drivers/gpu/drm/drm_file.c
> @@ -608,7 +608,8 @@ ssize_t drm_read(struct file *filp, char __user *buffer,
>  				file_priv->event_space -= length;
>  				list_add(&e->link, &file_priv->event_list);
>  				spin_unlock_irq(&dev->event_lock);
> -				wake_up_interruptible(&file_priv->event_wait);
> +				wake_up_interruptible_poll(&file_priv->event_wait,
> +					EPOLLIN | EPOLLRDNORM);
>  				break;
>  			}
>  
> @@ -804,7 +805,8 @@ void drm_send_event_locked(struct drm_device *dev, struct drm_pending_event *e)
>  	list_del(&e->pending_link);
>  	list_add_tail(&e->link,
>  		      &e->file_priv->event_list);
> -	wake_up_interruptible(&e->file_priv->event_wait);
> +	wake_up_interruptible_poll(&e->file_priv->event_wait,
> +		EPOLLIN | EPOLLRDNORM);
>  }
>  EXPORT_SYMBOL(drm_send_event_locked);
>  
> -- 
> 2.26.1
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

^ permalink raw reply	[flat|nested] 4+ messages in thread
* Re: [PATCH v2] drm: make drm_file use keyed wakeups
  2020-04-24 16:26 [PATCH v2] drm: make drm_file use keyed wakeups Kenny Levinsen
  2020-04-28 15:14 ` Daniel Vetter
@ 2020-04-29 11:19 ` kl
  2020-04-30 14:04   ` Daniel Vetter
  1 sibling, 1 reply; 4+ messages in thread
From: kl @ 2020-04-29 11:19 UTC (permalink / raw)
  To: Daniel Vetter
  Cc: intel-gfx, dri-devel, airlied, tzimmermann, mripard,
	maarten.lankhorst, linux-kernel

April 28, 2020 5:14 PM, "Daniel Vetter" <daniel@ffwll.ch> wrote:

> On Fri, Apr 24, 2020 at 06:26:15PM +0200, Kenny Levinsen wrote:
> 
>> Some processes, such as systemd, are only polling for EPOLLERR|EPOLLHUP.
>> As drm_file uses unkeyed wakeups, such a poll can receive many spurious
>> wakeups from uninteresting events if, for example, the file description
>> is subscribed to vblank events. This is the case with systemd, as it
>> polls a file description from logind that is shared with the users'
>> compositor.
>> 
>> Use keyed wakeups to allow the wakeup target to more efficiently discard
>> these uninteresting events.
>> 
>> Signed-off-by: Kenny Levinsen <kl@kl.wtf>
> 
> Hm I applied v1 and I'm not spotting what's different here, and there's no
> changelog explaining what changed ...
> 
> Please send a fixup if there's anything important missing.
> -Daniel
>

It's only the summary that differed as you and sravn requested in #dri-devel, so it's probably fine.

I should have explained the change. I'm still trying to get the hang of the email-based workflow. :)

Best regards,
Kenny Levinsen

>> ---
>> drivers/gpu/drm/drm_file.c | 6 ++++--
>> 1 file changed, 4 insertions(+), 2 deletions(-)
>> 
>> diff --git a/drivers/gpu/drm/drm_file.c b/drivers/gpu/drm/drm_file.c
>> index c4c704e01961..ec25b3d979d9 100644
>> --- a/drivers/gpu/drm/drm_file.c
>> +++ b/drivers/gpu/drm/drm_file.c
>> @@ -608,7 +608,8 @@ ssize_t drm_read(struct file *filp, char __user *buffer,
>> file_priv->event_space -= length;
>> list_add(&e->link, &file_priv->event_list);
>> spin_unlock_irq(&dev->event_lock);
>> - wake_up_interruptible(&file_priv->event_wait);
>> + wake_up_interruptible_poll(&file_priv->event_wait,
>> + EPOLLIN | EPOLLRDNORM);
>> break;
>> }
>> 
>> @@ -804,7 +805,8 @@ void drm_send_event_locked(struct drm_device *dev, struct drm_pending_event *e)
>> list_del(&e->pending_link);
>> list_add_tail(&e->link,
>> &e->file_priv->event_list);
>> - wake_up_interruptible(&e->file_priv->event_wait);
>> + wake_up_interruptible_poll(&e->file_priv->event_wait,
>> + EPOLLIN | EPOLLRDNORM);
>> }
>> EXPORT_SYMBOL(drm_send_event_locked);
>> 
>> --
>> 2.26.1
> 
> --
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch

^ permalink raw reply	[flat|nested] 4+ messages in thread
* Re: [PATCH v2] drm: make drm_file use keyed wakeups
  2020-04-29 11:19 ` kl
@ 2020-04-30 14:04   ` Daniel Vetter
  0 siblings, 0 replies; 4+ messages in thread
From: Daniel Vetter @ 2020-04-30 14:04 UTC (permalink / raw)
  To: kl
  Cc: Daniel Vetter, intel-gfx, dri-devel, airlied, tzimmermann,
	mripard, maarten.lankhorst, linux-kernel

On Wed, Apr 29, 2020 at 11:19:07AM +0000, kl@kl.wtf wrote:
> April 28, 2020 5:14 PM, "Daniel Vetter" <daniel@ffwll.ch> wrote:
> 
> > On Fri, Apr 24, 2020 at 06:26:15PM +0200, Kenny Levinsen wrote:
> > 
> >> Some processes, such as systemd, are only polling for EPOLLERR|EPOLLHUP.
> >> As drm_file uses unkeyed wakeups, such a poll can receive many spurious
> >> wakeups from uninteresting events if, for example, the file description
> >> is subscribed to vblank events. This is the case with systemd, as it
> >> polls a file description from logind that is shared with the users'
> >> compositor.
> >> 
> >> Use keyed wakeups to allow the wakeup target to more efficiently discard
> >> these uninteresting events.
> >> 
> >> Signed-off-by: Kenny Levinsen <kl@kl.wtf>
> > 
> > Hm I applied v1 and I'm not spotting what's different here, and there's no
> > changelog explaining what changed ...
> > 
> > Please send a fixup if there's anything important missing.
> > -Daniel
> >
> 
> It's only the summary that differed as you and sravn requested in #dri-devel, so it's probably fine.
> 
> I should have explained the change. I'm still trying to get the hang of the email-based workflow. :)

Oops sorry, I generally run as a stateless maintainer so forgot :-/

And yes email based workflow is full of warts, it's a pain.
-Daniel

> 
> Best regards,
> Kenny Levinsen
> 
> >> ---
> >> drivers/gpu/drm/drm_file.c | 6 ++++--
> >> 1 file changed, 4 insertions(+), 2 deletions(-)
> >> 
> >> diff --git a/drivers/gpu/drm/drm_file.c b/drivers/gpu/drm/drm_file.c
> >> index c4c704e01961..ec25b3d979d9 100644
> >> --- a/drivers/gpu/drm/drm_file.c
> >> +++ b/drivers/gpu/drm/drm_file.c
> >> @@ -608,7 +608,8 @@ ssize_t drm_read(struct file *filp, char __user *buffer,
> >> file_priv->event_space -= length;
> >> list_add(&e->link, &file_priv->event_list);
> >> spin_unlock_irq(&dev->event_lock);
> >> - wake_up_interruptible(&file_priv->event_wait);
> >> + wake_up_interruptible_poll(&file_priv->event_wait,
> >> + EPOLLIN | EPOLLRDNORM);
> >> break;
> >> }
> >> 
> >> @@ -804,7 +805,8 @@ void drm_send_event_locked(struct drm_device *dev, struct drm_pending_event *e)
> >> list_del(&e->pending_link);
> >> list_add_tail(&e->link,
> >> &e->file_priv->event_list);
> >> - wake_up_interruptible(&e->file_priv->event_wait);
> >> + wake_up_interruptible_poll(&e->file_priv->event_wait,
> >> + EPOLLIN | EPOLLRDNORM);
> >> }
> >> EXPORT_SYMBOL(drm_send_event_locked);
> >> 
> >> --
> >> 2.26.1
> > 
> > --
> > Daniel Vetter
> > Software Engineer, Intel Corporation
> > http://blog.ffwll.ch

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

^ permalink raw reply	[flat|nested] 4+ messages in thread
end of thread, other threads:[~2020-04-30 14:04 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-04-24 16:26 [PATCH v2] drm: make drm_file use keyed wakeups Kenny Levinsen
2020-04-28 15:14 ` Daniel Vetter
2020-04-29 11:19 ` kl
2020-04-30 14:04   ` Daniel Vetter

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).