[Bug 109408] [Kabylake] RPS waitboost regression since v4.20

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=109408

--- Comment #2 from Lyude Paul <lyude at redhat.com> ---
(In reply to Chris Wilson from comment #1)
> One positive aspect here is that it seems both systems do employ the
> "interactive" mode: that is a fixed set of EI thresholds biased to
> upclocking the GPU. That is positive as it implies that the low frequencies
> may be more to do with low EI busyness than anything else. The last tweak to
> waitboosting that I recall was the very same interactive mode,
> 
> commit 027063b1606fea6df15c270e5f2a072d1dfa8fef [v4.19]
> Author: Chris Wilson <chris at chris-wilson.co.uk>
> Date:   Tue Jul 31 14:26:29 2018 +0100
> 
>     drm/i915: Interactive RPS mode
> 
> and before that
> 
> commit e9af4ea2b9e7e5d3caa6354be14de06b678ed0fa [v4.17]
> Author: Chris Wilson <chris at chris-wilson.co.uk>
> Date:   Thu Jan 18 13:16:09 2018 +0000
> 
>     drm/i915: Avoid waitboosting on the active request
> 
> So I think this may have been an accident. :)
> 
> Taking a wild guess:
> 
> commit 08e3e21a24d23db6a4adca90f7cb40d69e09d35c
> Author: Lucas De Marchi <lucas.demarchi at intel.com>
> Date:   Fri Aug 3 16:24:43 2018 -0700
> 
>     drm/i915: kill resource streamer support
> 
> (It's both new to v4.20 and had unexpected perf implications.)

Unfortunately reverting 08e3e21a24d23db6a4adca90f7cb40d69e09d35c doesn't seem
to have made any noticeable difference, would you like me to try anything else?

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