On Fri, Mar 20, 2015 at 12:31:16PM -0700, Jesse Barnes wrote:
> On 03/20/2015 12:28 PM, ville.syrjala@xxxxxxxxxxxxxxx wrote:
> > From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> >
> > msleep() can sleep for way too long, so switch wait_for() to use
> > usleep_range() instead. Following a totally unscientific method
> > I just picked the range as W-2W.
> >
> > This cuts the i915 init time on my BSW to almost half:
> > - initcall i915_init+0x0/0xa8 [i915] returned 0 after 419977 usecs
> > + initcall i915_init+0x0/0xa8 [i915] returned 0 after 238419 usecs
> >
> > Note that I didn't perform any other benchmarks on this so far.
> >
> > Cc: Jesse Barnes <jbarnes@xxxxxxxxxxxxxxxx>
> > Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> > ---
> > drivers/gpu/drm/i915/intel_drv.h | 4 ++--
> > 1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> > index 6f20f3a..d2a4de0 100644
> > --- a/drivers/gpu/drm/i915/intel_drv.h
> > +++ b/drivers/gpu/drm/i915/intel_drv.h
> > @@ -56,8 +56,8 @@
> > ret__ = -ETIMEDOUT; \
> > break; \
> > } \
> > - if (W && drm_can_sleep()) { \
> > - msleep(W); \
> > + if ((W) && drm_can_sleep()) { \
> > + usleep_range((W)*1000, (W)*2000); \
> > } else { \
> > cpu_relax(); \
> > } \
> >
>
> Nice improvement! I guess it's just because usleep_range() uses an
> hrtimeout, but since we have the added slop of the range it may actually
> be an improvement, power-wise too.
>
> Reviewed-by: Jesse Barnes <jbarnes@xxxxxxxxxxxxxxxx>
Nice indeed. Queued for -next, thanks for the patch.
-Daniel
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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