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>
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