[Intel-gfx] [PATCH 9/9] drm/i915/gt: Restore aggressive post-boost downclocking

[Chris Wilson]

Quoting Chris Wilson (2020-04-27 13:40:46)
> Quoting Chris Wilson (2020-04-27 09:54:08)
> > We reduced the clocks slowly after a boost event based on the
> > observation that the smoothness of animations suffered. However, since
> > reducing the evalution intervals, we should be able to respond to the
> > rapidly fluctuating workload of a simple desktop animation and so
> > restore the more aggressive downclocking.
> > 
> > References: 2a8862d2f3da ("drm/i915: Reduce the RPS shock")
> > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> 
> *** ANECDOTAL ***

> I spot checked a few games during scenes where the GPU was not capped
> out, and it was drawing about ~100MHz less for ~1W less.

For example, vsync'ed Talos,

hw: 59.7
2553.86,Joules,power/energy-pkg/,192545269820,100.00,,
1355.92,Joules,power/energy-cores/,192545266374,100.00,,
556.36,Joules,power/energy-gpu/,192545263536,100.00,,
86989,M,i915/actual-frequency/,192545247535,100.00,,
12736813129,ns,i915/rc6-residency/,192545239813,100.00,,
118321566117,ns,i915/rcs0-busy/,192545235095,100.00,,
0,ns,i915/bcs0-busy/,192545229596,100.00,,
0,ns,i915/vcs0-busy/,192545222782,100.00,,

manual: 59.7
2490.58,Joules,power/energy-pkg/,190751537693,100.00,,
1447.89,Joules,power/energy-cores/,190751542360,100.00,,
394.93,Joules,power/energy-gpu/,190751543518,100.00,,
67956,M,i915/actual-frequency/,190751526709,100.00,,
40240837120,ns,i915/rc6-residency/,190751523820,100.00,,
147090761985,ns,i915/rcs0-busy/,190751525291,100.00,,
0,ns,i915/bcs0-busy/,190751523611,100.00,,
0,ns,i915/vcs0-busy/,190751520733,100.00,,

> *** ANECDOTAL ***