On Fri, 28 Nov 2014, Daniel Vetter <daniel.vetter@xxxxxxxx> wrote: > So apparently jiffies<->nsec<->ktime isn't accurate or something. At > elast if we timeout there's occasionally still a few hundred us left > (in a 2 second timeout). > > Stuff I've tried and thrown out again: > - Sampling the before timestamp before jiffies. Doesn't improve test > path rate at all. > - Using jiffies. Way to inaccurate, which means way too much drift > with signals plus automatic ioctl restarting in userspace. In > hindsight we should have used an absolute timeout, but hey we need > something for v3 of the i915 gem wait interfaces ;-) > - Trying to figure out where accuracy gets lost. gl testcase really > don't care all that much about this (as long as isn't not massively > off), it's just that the testcase gets a bit upset if it receives an > EITME with timeout > 0. > > So as long as we're in the ballbark it's good enough. So patch > everything up if we're at most one jiffies off. I get's me a solid > test again. > > This regression is probably introduced in > > commit 5ed0bdf21a85d78e04f89f15ccf227562177cbd9 > Author: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > Date: Wed Jul 16 21:05:06 2014 +0000 > > drm: i915: Use nsec based interfaces > > Use ktime_get_raw_ns() and get rid of the back and forth timespec > conversions. > > Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > Acked-by: Daniel Vetter <daniel.vetter@xxxxxxxx> > Signed-off-by: John Stultz <john.stultz@xxxxxxxxxx> > > Probably because I'm too lazy to confirm myself and still waiting for > QA ;-) > > Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > Cc: John Stultz <john.stultz@xxxxxxxxxx> > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=82749 > Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxxx> Pushed to drm-intel-next-fixes, thanks for the patch. BR, Jani. > --- > drivers/gpu/drm/i915/i915_gem.c | 10 ++++++++++ > 1 file changed, 10 insertions(+) > > diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c > index 002730d1409b..abdc5bcdbd0d 100644 > --- a/drivers/gpu/drm/i915/i915_gem.c > +++ b/drivers/gpu/drm/i915/i915_gem.c > @@ -1302,6 +1302,16 @@ int __i915_wait_seqno(struct intel_engine_cs *ring, u32 seqno, > s64 tres = *timeout - (now - before); > > *timeout = tres < 0 ? 0 : tres; > + > + /* > + * Apparently ktime isn't accurate enough and occasionally has a > + * bit of mismatch in the jiffies<->nsecs<->ktime loop. So patch > + * things up to make the test happy. We allow up to 1 jiffy. > + * > + * This is a regrssion from the timespec->ktime conversion. > + */ > + if (ret == -ETIME && *timeout < jiffies_to_usecs(1)*1000) > + *timeout = 0; > } > > return ret; > -- > 1.9.3 > > _______________________________________________ > Intel-gfx mailing list > Intel-gfx@xxxxxxxxxxxxxxxxxxxxx > http://lists.freedesktop.org/mailman/listinfo/intel-gfx -- Jani Nikula, Intel Open Source Technology Center _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
