On Tue, Mar 28, 2023 at 8:28 AM Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx> wrote: > > On 25/03/2023 00:00, Rob Clark wrote: > > From: Rob Clark <robdclark@xxxxxxxxxxxx> > > > > If userspace asked for a timeout greater than zero, but less than a > > jiffy, they clearly weren't planning on spinning. So it is better > > to round up to one. > > > > This fixes an issue with supertuxkart that was (for some reason) > > spinning on a gl sync with 1ms timeout. CPU time for a demo lap > > drops from: > > > > 15.83user 20.98system 0:47.46elapsed 77%CPU > > > > to: > > > > 8.84user 2.30system 0:46.67elapsed 23%CPU > > Interesting. We potentially increased the timeout, but the overall > (elapsed) time has decreased. Nevertheless: There is some randomness from run to run so small variations in total --profile-laps=N time are normal. So I wouldn't read too much into that, compared to %CPU. This shouldn't really change how long it takes for the fence to signal, as much as just prevent the CPU from busy looping until the fence does signal ;-) (In theory the CPU busy looping could cause GPU thermal throttling, but I don't think that was happening in this case.) > Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx> thx > > > > Signed-off-by: Rob Clark <robdclark@xxxxxxxxxxxx> > > --- > > drivers/gpu/drm/msm/msm_drv.h | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/gpu/drm/msm/msm_drv.h b/drivers/gpu/drm/msm/msm_drv.h > > index 9f0c184b02a0..7936aa6cad03 100644 > > --- a/drivers/gpu/drm/msm/msm_drv.h > > +++ b/drivers/gpu/drm/msm/msm_drv.h > > @@ -548,7 +548,7 @@ static inline unsigned long timeout_to_jiffies(const ktime_t *timeout) > > remaining_jiffies = ktime_divns(rem, NSEC_PER_SEC / HZ); > > } > > > > - return clamp(remaining_jiffies, 0LL, (s64)INT_MAX); > > + return clamp(remaining_jiffies, 1LL, (s64)INT_MAX); > > } > > > > /* Driver helpers */ > > -- > With best wishes > Dmitry >
