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

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Message-ID: <CAKPKb8_8uQdzNevB4wVpXcRrBr0-rjfvBR=oNNyCCA4yASgK-g@mail.gmail.com>
Date: Tue, 7 Oct 2025 16:21:34 +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 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