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

[Jan Vesely]

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

> Am 03.08.19 um 02:09 schrieb Andi Kleen:
> > From: Andi Kleen <ak at 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 at 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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