[PATCH] radeon: Use only a single work queue thread for crt

[PATCH] radeon: Use only a single work queue thread for crt

[Andi Kleen]

From: Andi Kleen <ak@linux.intel.com>

I got tired of seeing a lot of radeon-crt kernel threads in ps on my
workstation, one for each CPU and one for each display, which never use any CPU time.
Surely a single kernel thread is enough to handle the display.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
---
 drivers/gpu/drm/radeon/radeon_display.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/radeon/radeon_display.c b/drivers/gpu/drm/radeon/radeon_display.c
index bd52f15e6330..fb0ca688f6fe 100644
--- a/drivers/gpu/drm/radeon/radeon_display.c
+++ b/drivers/gpu/drm/radeon/radeon_display.c
@@ -682,7 +682,7 @@ static void radeon_crtc_init(struct drm_device *dev, int index)
 
 	drm_mode_crtc_set_gamma_size(&radeon_crtc->base, 256);
 	radeon_crtc->crtc_id = index;
-	radeon_crtc->flip_queue = alloc_workqueue("radeon-crtc", WQ_HIGHPRI, 0);
+	radeon_crtc->flip_queue = alloc_workqueue("radeon-crtc", WQ_HIGHPRI|WQ_UNBOUND, 0);
 	rdev->mode_info.crtcs[index] = radeon_crtc;
 
 	if (rdev->family >= CHIP_BONAIRE) {
-- 
2.20.1

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Re: [PATCH] radeon: Use only a single work queue thread for crt

[Paul Menzel]

Dear Andi,


Am 03.08.19 um 02:09 schrieb Andi Kleen:
> From: Andi Kleen <ak@linux.intel.com>
> 
> I got tired of seeing a lot of radeon-crt kernel threads in ps on my
> workstation, one for each CPU and one for each display, which never use any CPU time.
> Surely a single kernel thread is enough to handle the display.
> 
> Signed-off-by: Andi Kleen <ak@linux.intel.com>
> ---
>   drivers/gpu/drm/radeon/radeon_display.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/radeon/radeon_display.c b/drivers/gpu/drm/radeon/radeon_display.c
> index bd52f15e6330..fb0ca688f6fe 100644
> --- a/drivers/gpu/drm/radeon/radeon_display.c
> +++ b/drivers/gpu/drm/radeon/radeon_display.c
> @@ -682,7 +682,7 @@ static void radeon_crtc_init(struct drm_device *dev, int index)
>   
>   	drm_mode_crtc_set_gamma_size(&radeon_crtc->base, 256);
>   	radeon_crtc->crtc_id = index;
> -	radeon_crtc->flip_queue = alloc_workqueue("radeon-crtc", WQ_HIGHPRI, 0);
> +	radeon_crtc->flip_queue = alloc_workqueue("radeon-crtc", WQ_HIGHPRI|WQ_UNBOUND, 0);
>   	rdev->mode_info.crtcs[index] = radeon_crtc;
>   
>   	if (rdev->family >= CHIP_BONAIRE) {

Reviewed-by: Paul Menzel <pmenzel@molgen.mpg.de>


Kind regards,

Paul
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Re: [PATCH] radeon: Use only a single work queue thread for crt

[Christian König]

Am 03.08.19 um 02:09 schrieb Andi Kleen:
> From: Andi Kleen <ak@linux.intel.com>
>
> I got tired of seeing a lot of radeon-crt kernel threads in ps on my
> workstation, one for each CPU and one for each display, which never use any CPU time.
> Surely a single kernel thread is enough to handle the display.

NAK, radeon blocks inside the kernel thread and those need to run in 
parallel or otherwise the hardware can hang.

Christian.

>
> Signed-off-by: Andi Kleen <ak@linux.intel.com>
> ---
>   drivers/gpu/drm/radeon/radeon_display.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/radeon/radeon_display.c b/drivers/gpu/drm/radeon/radeon_display.c
> index bd52f15e6330..fb0ca688f6fe 100644
> --- a/drivers/gpu/drm/radeon/radeon_display.c
> +++ b/drivers/gpu/drm/radeon/radeon_display.c
> @@ -682,7 +682,7 @@ static void radeon_crtc_init(struct drm_device *dev, int index)
>   
>   	drm_mode_crtc_set_gamma_size(&radeon_crtc->base, 256);
>   	radeon_crtc->crtc_id = index;
> -	radeon_crtc->flip_queue = alloc_workqueue("radeon-crtc", WQ_HIGHPRI, 0);
> +	radeon_crtc->flip_queue = alloc_workqueue("radeon-crtc", WQ_HIGHPRI|WQ_UNBOUND, 0);
>   	rdev->mode_info.crtcs[index] = radeon_crtc;
>   
>   	if (rdev->family >= CHIP_BONAIRE) {

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Re: [PATCH] radeon: Use only a single work queue thread for crt

[Jan Vesely]

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On Sun, Sep 6, 2020 at 4:54 AM Christian König <
ckoenig.leichtzumerken@gmail.com> wrote:

> Am 03.08.19 um 02:09 schrieb Andi Kleen:
> > From: Andi Kleen <ak@linux.intel.com>
> >
> > I got tired of seeing a lot of radeon-crt kernel threads in ps on my
> > workstation, one for each CPU and one for each display, which never use
> any CPU time.
> > Surely a single kernel thread is enough to handle the display.
>
> NAK, radeon blocks inside the kernel thread and those need to run in
> parallel or otherwise the hardware can hang.
>

Shouldn't WQ_UNBOUND create a new worker thread whenever all current
workers go to sleep/block (and the total number of worker threads is below
'max_active') ?

Jan

>
> Christian.
>
> >
> > Signed-off-by: Andi Kleen <ak@linux.intel.com>
> > ---
> >   drivers/gpu/drm/radeon/radeon_display.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/radeon/radeon_display.c
> b/drivers/gpu/drm/radeon/radeon_display.c
> > index bd52f15e6330..fb0ca688f6fe 100644
> > --- a/drivers/gpu/drm/radeon/radeon_display.c
> > +++ b/drivers/gpu/drm/radeon/radeon_display.c
> > @@ -682,7 +682,7 @@ static void radeon_crtc_init(struct drm_device *dev,
> int index)
> >
> >       drm_mode_crtc_set_gamma_size(&radeon_crtc->base, 256);
> >       radeon_crtc->crtc_id = index;
> > -     radeon_crtc->flip_queue = alloc_workqueue("radeon-crtc",
> WQ_HIGHPRI, 0);
> > +     radeon_crtc->flip_queue = alloc_workqueue("radeon-crtc",
> WQ_HIGHPRI|WQ_UNBOUND, 0);
> >       rdev->mode_info.crtcs[index] = radeon_crtc;
> >
> >       if (rdev->family >= CHIP_BONAIRE) {
>
> _______________________________________________
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> amd-gfx@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/amd-gfx
>

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Re: [PATCH] radeon: Use only a single work queue thread for crt

[Christian König]

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Am 06.09.20 um 18:02 schrieb Jan Vesely:
>
>
> On Sun, Sep 6, 2020 at 4:54 AM Christian König 
> <ckoenig.leichtzumerken@gmail.com 
> <mailto:ckoenig.leichtzumerken@gmail.com>> wrote:
>
>     Am 03.08.19 um 02:09 schrieb Andi Kleen:
>     > From: Andi Kleen <ak@linux.intel.com <mailto:ak@linux.intel.com>>
>     >
>     > I got tired of seeing a lot of radeon-crt kernel threads in ps on my
>     > workstation, one for each CPU and one for each display, which
>     never use any CPU time.
>     > Surely a single kernel thread is enough to handle the display.
>
>     NAK, radeon blocks inside the kernel thread and those need to run in
>     parallel or otherwise the hardware can hang.
>
>
> Shouldn't WQ_UNBOUND create a new worker thread whenever all current 
> workers go to sleep/block (and the total number of worker threads is 
> below 'max_active') ?

If that is guaranteed then this is indeed sufficient, but the sentence 
"Surely a single kernel thread is enough to handle the display." sounded 
like it creates only a single one.

Christian.

>
> Jan
>
>
>     Christian.
>
>     >
>     > Signed-off-by: Andi Kleen <ak@linux.intel.com
>     <mailto:ak@linux.intel.com>>
>     > ---
>     >   drivers/gpu/drm/radeon/radeon_display.c | 2 +-
>     >   1 file changed, 1 insertion(+), 1 deletion(-)
>     >
>     > diff --git a/drivers/gpu/drm/radeon/radeon_display.c
>     b/drivers/gpu/drm/radeon/radeon_display.c
>     > index bd52f15e6330..fb0ca688f6fe 100644
>     > --- a/drivers/gpu/drm/radeon/radeon_display.c
>     > +++ b/drivers/gpu/drm/radeon/radeon_display.c
>     > @@ -682,7 +682,7 @@ static void radeon_crtc_init(struct
>     drm_device *dev, int index)
>     >
>     >  drm_mode_crtc_set_gamma_size(&radeon_crtc->base, 256);
>     >       radeon_crtc->crtc_id = index;
>     > -     radeon_crtc->flip_queue = alloc_workqueue("radeon-crtc",
>     WQ_HIGHPRI, 0);
>     > +     radeon_crtc->flip_queue = alloc_workqueue("radeon-crtc",
>     WQ_HIGHPRI|WQ_UNBOUND, 0);
>     >       rdev->mode_info.crtcs[index] = radeon_crtc;
>     >
>     >       if (rdev->family >= CHIP_BONAIRE) {
>
>     _______________________________________________
>     amd-gfx mailing list
>     amd-gfx@lists.freedesktop.org <mailto:amd-gfx@lists.freedesktop.org>
>     https://lists.freedesktop.org/mailman/listinfo/amd-gfx
>
>
> _______________________________________________
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> amd-gfx@lists.freedesktop.org
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Re: [PATCH] radeon: Use only a single work queue thread for crt

[Dave Airlie]

On Sun, 6 Sep 2020 at 18:54, Christian König
<ckoenig.leichtzumerken@gmail.com> wrote:
>
> Am 03.08.19 um 02:09 schrieb Andi Kleen:
> > From: Andi Kleen <ak@linux.intel.com>
> >
> > I got tired of seeing a lot of radeon-crt kernel threads in ps on my
> > workstation, one for each CPU and one for each display, which never use any CPU time.
> > Surely a single kernel thread is enough to handle the display.
>
> NAK, radeon blocks inside the kernel thread and those need to run in
> parallel or otherwise the hardware can hang.

Do we need one per cpu? or is one per crtc enough?

Dave.
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Re: [PATCH] radeon: Use only a single work queue thread for crt

[Christian König]

Am 07.09.20 um 01:47 schrieb Dave Airlie:
> On Sun, 6 Sep 2020 at 18:54, Christian König
> <ckoenig.leichtzumerken@gmail.com> wrote:
>> Am 03.08.19 um 02:09 schrieb Andi Kleen:
>>> From: Andi Kleen <ak@linux.intel.com>
>>>
>>> I got tired of seeing a lot of radeon-crt kernel threads in ps on my
>>> workstation, one for each CPU and one for each display, which never use any CPU time.
>>> Surely a single kernel thread is enough to handle the display.
>> NAK, radeon blocks inside the kernel thread and those need to run in
>> parallel or otherwise the hardware can hang.
> Do we need one per cpu? or is one per crtc enough?

One per CRTC is enough, but the patch description sounds like it creates 
only a global one.

Christian.

>
> Dave.

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