linux-kernel - Re: [PATCH] drm/vmwgfx: Replace schedule() with schedule

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Message-ID: <CAKPKb8-JE5W58jQOFSxr74sguoRop=3BH9EsVid-dXyGZkEpCA@mail.gmail.com>
Date: Sat, 18 Oct 2025 14:52:14 +0530
From: opensource india <opensource206@...il.com>
To: zack.rusin@...adcom.com, maarten.lankhorst@...ux.intel.com, 
	mripard@...nel.org, tzimmermann@...e.de, airlied@...il.com, simona@...ll.ch
Cc: bcm-kernel-feedback-list@...adcom.com, dri-devel@...ts.freedesktop.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/vmwgfx: Replace schedule() with schedule_hrtimeout()
 in fallback wait

On Tue, Oct 7, 2025 at 4:21 PM opensource india <opensource206@...il.com> wrote:
>
> On Sun, Sep 28, 2025 at 11:19 AM Pavan Bobba <opensource206@...il.com> wrote:
> >
> > Replace the open-coded polling with schedule() in vmw_fallback_wait()
> > by schedule_hrtimeout(). The old code wakes up at jiffy granularity and
> > leads to unnecessary CPU wakeups during fence waits.
> >
> > schedule_hrtimeout() provides high-resolution sleep with finer control,
> > reducing CPU utilization without affecting fence correctness. For the
> > non-interruptible case, use schedule_timeout_uninterruptible().
> >
> > Signed-off-by: Pavan Bobba <opensource206@...il.com>
> > ---
> >  drivers/gpu/drm/vmwgfx/vmwgfx_irq.c | 16 ++++++----------
> >  1 file changed, 6 insertions(+), 10 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_irq.c b/drivers/gpu/drm/vmwgfx/vmwgfx_irq.c
> > index 05773eb394d3..64045b0efafc 100644
> > --- a/drivers/gpu/drm/vmwgfx/vmwgfx_irq.c
> > +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_irq.c
> > @@ -202,16 +202,12 @@ int vmw_fallback_wait(struct vmw_private *dev_priv,
> >                 if (lazy)
> >                         schedule_timeout(1);
> >                 else if ((++count & 0x0F) == 0) {
> > -                       /**
> > -                        * FIXME: Use schedule_hr_timeout here for
> > -                        * newer kernels and lower CPU utilization.
> > -                        */
> > -
> > -                       __set_current_state(TASK_RUNNING);
> > -                       schedule();
> > -                       __set_current_state((interruptible) ?
> > -                                           TASK_INTERRUPTIBLE :
> > -                                           TASK_UNINTERRUPTIBLE);
> > +                       ktime_t delta = ktime_set(0, NSEC_PER_MSEC);
> > +
> > +                       if (interruptible)
> > +                               schedule_hrtimeout(&delta, HRTIMER_MODE_REL);
> > +                       else
> > +                               schedule_timeout_uninterruptible(delta);
> >                 }
> >                 if (interruptible && signal_pending(current)) {
> >                         ret = -ERESTARTSYS;
> > --
> > 2.43.0
> >
>
> anyone please review this patch?

Hi all, can anyone please review this?