Re: [Intel-gfx] [PATCH] drm/i915: use udelay for very short delays

2016-12-15 Thread Daniel Vetter
On Thu, Dec 15, 2016 at 11:51 AM, Nicholas Mc Guire wrote: > On Thu, Dec 15, 2016 at 10:27:59AM +0100, Daniel Vetter wrote: >> On Thu, Dec 15, 2016 at 10:25:19AM +0100, Daniel Vetter wrote: >> > On Thu, Dec 15, 2016 at 11:08:49AM +0200, Jani Nikula wrote: >> > > On Thu, 15 Dec 2016, Nicholas Mc Gu

Re: [Intel-gfx] [PATCH] drm/i915: use udelay for very short delays

2016-12-15 Thread Nicholas Mc Guire
On Thu, Dec 15, 2016 at 10:27:59AM +0100, Daniel Vetter wrote: > On Thu, Dec 15, 2016 at 10:25:19AM +0100, Daniel Vetter wrote: > > On Thu, Dec 15, 2016 at 11:08:49AM +0200, Jani Nikula wrote: > > > On Thu, 15 Dec 2016, Nicholas Mc Guire wrote: > > > > Even on fast systems a 2 microsecond delay is

Re: [Intel-gfx] [PATCH] drm/i915: use udelay for very short delays

2016-12-15 Thread Daniel Vetter
On Thu, Dec 15, 2016 at 10:25:19AM +0100, Daniel Vetter wrote: > On Thu, Dec 15, 2016 at 11:08:49AM +0200, Jani Nikula wrote: > > On Thu, 15 Dec 2016, Nicholas Mc Guire wrote: > > > Even on fast systems a 2 microsecond delay is most likely more efficient > > > as a busy-wait loop. The overhead of

Re: [Intel-gfx] [PATCH] drm/i915: use udelay for very short delays

2016-12-15 Thread Daniel Vetter
On Thu, Dec 15, 2016 at 11:08:49AM +0200, Jani Nikula wrote: > On Thu, 15 Dec 2016, Nicholas Mc Guire wrote: > > Even on fast systems a 2 microsecond delay is most likely more efficient > > as a busy-wait loop. The overhead of a hrtimer does not seem warranted - > > change this to a udelay(2). >