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

On Thu, 15 Dec 2016, Nicholas Mc Guire wrote: > On Thu, Dec 15, 2016 at 12:20:01PM +0200, Jani Nikula wrote: >> On Thu, 15 Dec 2016, Ville Syrjälä wrote: >> > On Thu, Dec 15, 2016 at 11:52:34AM +0200, Jani Nikula wrote: >> >> On Thu, 15 Dec 2016,

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

On Thu, 15 Dec 2016, Nicholas Mc Guire wrote: > On Thu, Dec 15, 2016 at 12:20:01PM +0200, Jani Nikula wrote: >> On Thu, 15 Dec 2016, Ville Syrjälä wrote: >> > On Thu, Dec 15, 2016 at 11:52:34AM +0200, Jani Nikula wrote: >> >> On Thu, 15 Dec 2016, Nicholas Mc Guire wrote: >> >> > On Thu, Dec 15,

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

On Thu, Dec 15, 2016 at 10:34:00AM +, Nicholas Mc Guire wrote: > On Thu, Dec 15, 2016 at 12:20:01PM +0200, Jani Nikula wrote: > > On Thu, 15 Dec 2016, Ville Syrjälä wrote: > > > On Thu, Dec 15, 2016 at 11:52:34AM +0200, Jani Nikula wrote: > > >> On Thu, 15 Dec

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

On Thu, Dec 15, 2016 at 10:34:00AM +, Nicholas Mc Guire wrote: > On Thu, Dec 15, 2016 at 12:20:01PM +0200, Jani Nikula wrote: > > On Thu, 15 Dec 2016, Ville Syrjälä wrote: > > > On Thu, Dec 15, 2016 at 11:52:34AM +0200, Jani Nikula wrote: > > >> On Thu, 15 Dec 2016, Nicholas Mc Guire wrote:

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

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

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

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

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

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

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

On Thu, Dec 15, 2016 at 12:20:01PM +0200, Jani Nikula wrote: > On Thu, 15 Dec 2016, Ville Syrjälä wrote: > > On Thu, Dec 15, 2016 at 11:52:34AM +0200, Jani Nikula wrote: > >> On Thu, 15 Dec 2016, Nicholas Mc Guire wrote: > >> > On Thu, Dec 15,

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

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

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

On Thu, Dec 15, 2016 at 12:20:01PM +0200, Jani Nikula wrote: > On Thu, 15 Dec 2016, Ville Syrjälä wrote: > > On Thu, Dec 15, 2016 at 11:52:34AM +0200, Jani Nikula wrote: > >> On Thu, 15 Dec 2016, Nicholas Mc Guire wrote: > >> > On Thu, Dec 15, 2016 at 11:08:49AM +0200, Jani Nikula wrote: > >> >>

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

On Thu, 15 Dec 2016, Ville Syrjälä wrote: > On Thu, Dec 15, 2016 at 11:52:34AM +0200, Jani Nikula wrote: >> On Thu, 15 Dec 2016, Nicholas Mc Guire wrote: >> > On Thu, Dec 15, 2016 at 11:08:49AM +0200, Jani Nikula wrote: >> >> On Thu, 15 Dec 2016,

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

On Thu, 15 Dec 2016, Ville Syrjälä wrote: > On Thu, Dec 15, 2016 at 11:52:34AM +0200, Jani Nikula wrote: >> On Thu, 15 Dec 2016, Nicholas Mc Guire 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

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

On Thu, Dec 15, 2016 at 11:52:34AM +0200, Jani Nikula wrote: > On Thu, 15 Dec 2016, Nicholas Mc Guire 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

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

On Thu, Dec 15, 2016 at 11:52:34AM +0200, Jani Nikula wrote: > On Thu, 15 Dec 2016, Nicholas Mc Guire 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

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

On Thu, 15 Dec 2016, Nicholas Mc Guire 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

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

On Thu, 15 Dec 2016, Nicholas Mc Guire 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 a hrtimer does not

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

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

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

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). >

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

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

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

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

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

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

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). >

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

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). Similar concerns as in [1]. We don't need the

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

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). Similar concerns as in [1]. We don't need the accuracy of udelay()

[PATCH] drm/i915: use udelay for very short delays

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). Signed-off-by: Nicholas Mc Guire --- Problem found by coccinelle: Patch was compile tested with:

[PATCH] drm/i915: use udelay for very short delays

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). Signed-off-by: Nicholas Mc Guire --- Problem found by coccinelle: Patch was compile tested with: x86_64_defconfig