On Fri, Nov 28, 2014 at 12:08 PM, Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> wrote: >> - 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 ;-) > > I am still trying to get my head around an ioctl that only works in > jiffie intervals where the jiffie is too inaccurate. The problem is the rounding down behaviour of jiffies - if you wake up sufficiently often compared to HZ that adds up surprisingly fast. Adding a flag for absolute timeouts might work better, but then we'd still need to make sure that with the back&forth conversion we don't end up rounding all the time. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
