On Sun, Sep 28, 2025 at 1:49 AM Pavan Bobba <[email protected]> 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 <[email protected]> > --- > 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; > --
I don't remember exactly the schedule family of functions but isn't schedule_hrtimeout leaving the task in a running state? In general it looks like with the patch the task's current state doesn't match what was expected, plus I'm not sure if I quite get why the uninterruptible non-lazy case is being replaced with a lazy wait of NSEC_PER_MSEC's. It'd be great if you could explain a little bit better what you're doing here because the commit message is missing an explanation for either of those. z
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