[Intel-gfx] [PATCH 4/6] drm/i915: Set our shrinker->batch to 4096 (~16MiB)

[Joonas Lahtinen]

On Sat, 2017-08-12 at 12:51 +0100, Chris Wilson wrote:
> Prefer to defer activating our GEM shrinker until we have a few
> megabytes to free; or we have accumulated sufficient mempressure by
> deferring the reclaim to force a shrink. The intent is that because our
> objects may typically be large, we are too effective at shrinking and
> are not rewarded for freeing more pages than the batch. It will also
> defer the initial shrinking to hopefully put it at a lower priority than
> say the buffer cache (although it will balance out over a number of
> reclaims, with GEM being more bursty).
> 
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> ---
>  drivers/gpu/drm/i915/i915_gem_shrinker.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_gem_shrinker.c b/drivers/gpu/drm/i915/i915_gem_shrinker.c
> index 5b8bc0e4f336..8bb17e9a52de 100644
> --- a/drivers/gpu/drm/i915/i915_gem_shrinker.c
> +++ b/drivers/gpu/drm/i915/i915_gem_shrinker.c
> @@ -461,6 +461,7 @@ void i915_gem_shrinker_init(struct drm_i915_private *dev_priv)
>  	dev_priv->mm.shrinker.scan_objects = i915_gem_shrinker_scan;
>  	dev_priv->mm.shrinker.count_objects = i915_gem_shrinker_count;
>  	dev_priv->mm.shrinker.seeks = DEFAULT_SEEKS;
> +	dev_priv->mm.shrinker.batch = 4096;

Did you try how this alone effects the runtime of two consequtive
gem.testlist runs? Is there some specific test/usecase that benefits
from this. We'd be the first one to set this, md/raid5.c sets it to 128
which is the default (0).

Regards, Joonas
-- 
Joonas Lahtinen
Open Source Technology Center
Intel Corporation