[Intel-gfx] [PATCH] drm/i915: Do not use iowait while waiting for the GPU

[Chris Wilson]

Quoting Chris Wilson (2018-07-27 19:43:12)
> A recent trend for cpufreq is to boost the CPU frequencies for
> iowaiters, in particularly to benefit high frequency I/O. We do the same
> and boost the GPU clocks to try and minimise time spent waiting for the
> GPU. However, as the igfx and CPU share the same TDP, boosting the CPU
> frequency will result in the GPU being throttled and its frequency being
> reduced. Thus declaring iowait negatively impacts on GPU throughput.
> 
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=107410
> References: 52ccc4314293 ("cpufreq: intel_pstate: HWP boost performance on IO wakeup")
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Tvrtko Ursulin <tvrtko.ursulin at linux.intel.com>
> Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
> Cc: Eero Tamminen <eero.t.tamminen at intel.com>
> Cc: Francisco Jerez <currojerez at riseup.net>
> ---
>  drivers/gpu/drm/i915/i915_request.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
> index 5c2c93cbab12..7ef7ade12073 100644
> --- a/drivers/gpu/drm/i915/i915_request.c
> +++ b/drivers/gpu/drm/i915/i915_request.c
> @@ -1330,7 +1330,7 @@ long i915_request_wait(struct i915_request *rq,
>                         goto complete;
>                 }
>  
> -               timeout = io_schedule_timeout(timeout);
> +               timeout = schedule_timeout(timeout);

Wrong one...
-Chris