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<b><a class="bz_bug_link
bz_status_NEW "
title="NEW - [Kabylake] RPS waitboost regression since v4.20"
href="https://bugs.freedesktop.org/show_bug.cgi?id=109408#c2">Comment # 2</a>
on <a class="bz_bug_link
bz_status_NEW "
title="NEW - [Kabylake] RPS waitboost regression since v4.20"
href="https://bugs.freedesktop.org/show_bug.cgi?id=109408">bug 109408</a>
from <span class="vcard"><a class="email" href="mailto:lyude@redhat.com" title="Lyude Paul <lyude@redhat.com>"> <span class="fn">Lyude Paul</span></a>
</span></b>
<pre>(In reply to Chris Wilson from <a href="show_bug.cgi?id=109408#c1">comment #1</a>)
<span class="quote">> 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 <<a href="mailto:chris@chris-wilson.co.uk">chris@chris-wilson.co.uk</a>>
> Date: Tue Jul 31 14:26:29 2018 +0100
>
> drm/i915: Interactive RPS mode
>
> and before that
>
> commit e9af4ea2b9e7e5d3caa6354be14de06b678ed0fa [v4.17]
> Author: Chris Wilson <<a href="mailto:chris@chris-wilson.co.uk">chris@chris-wilson.co.uk</a>>
> 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 <<a href="mailto:lucas.demarchi@intel.com">lucas.demarchi@intel.com</a>>
> 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.)</span >
Unfortunately reverting 08e3e21a24d23db6a4adca90f7cb40d69e09d35c doesn't seem
to have made any noticeable difference, would you like me to try anything else?</pre>
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