Quoting Chris Wilson (2019-02-15 17:00:30) > Limit deboosting and boosting to keep ourselves at the extremes > when in the respective power modes (i.e. slowly decrease frequencies > while in the HIGH_POWER zone and slowly increase frequencies while > in the LOW_POWER zone). On idle, we will hit the timeout and drop > to the next level quickly, and conversely if busy we expect to > hit a waitboost and rapidly switch into max power. > > This should improve the UX experience by keeping the GPU clocks higher > than they ostensibly should be (based on simple busyness) by switching > into the INTERACTIVE mode (due to waiting for pageflips) and increasing > clocks via waitboosting. This will incur some additional power, our > saving grace should be rc6 and powergating to keep the extra current > draw in check. > > Food for future thought would be deadline scheduling? If we know certain > contexts (high priority compositors) absolutely must hit the next vblank > then we can raise the frequencies ahead of time. Part of this is covered > by per-context frequencies, where userspace is given control over the > frequency range they want the GPU to execute at (for largely the same > problem as this, where the workload is very latency sensitive but at the > EI level appears mostly idle). Indeed, the per-context series does > extend the modeset boosting to include a frequency range tweak which > seems applicable to solving this jittery UX behaviour. > > Reported-by: Lyude Paul <lyude@xxxxxxxxxx> > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=109408 > References: 0d55babc8392 ("drm/i915: Drop stray clearing of rps->last_adj") > References: 60548c554be2 ("drm/i915: Interactive RPS mode") > Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > Cc: Lyude Paul <lyude@xxxxxxxxxx> > Cc: Eero Tamminen <eero.t.tamminen@xxxxxxxxx> > Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx> > Cc: Michel Thierry <michel.thierry@xxxxxxxxx> Cribbed from Lyude on irc before reverting 0d55babc8392754352f1058866dd4182ae587d11: [4.20] 35 measurements Average: 33.65657142857143 FPS FPS observed: 20.8 - 46.87 FPS Percentage under 60 FPS: 100.0% Percentage under 55 FPS: 100.0% Percentage under 50 FPS: 100.0% Percentage under 45 FPS: 97.14285714285714% Percentage under 40 FPS: 97.14285714285714% Percentage under 35 FPS: 45.714285714285715% Percentage under 30 FPS: 11.428571428571429% Percentage under 25 FPS: 2.857142857142857% After reverting: [4.19 behaviour] 30 measurements Average: 49.833666666666666 FPS FPS observed: 33.85 - 60.0 FPS Percentage under 60 FPS: 86.66666666666667% Percentage under 55 FPS: 70.0% Percentage under 50 FPS: 53.333333333333336% Percentage under 45 FPS: 20.0% Percentage under 40 FPS: 6.666666666666667% Percentage under 35 FPS: 6.666666666666667% Percentage under 30 FPS: 0% Percentage under 25 FPS: 0% Patched: 42 measurements Average: 46.05428571428571 FPS FPS observed: 1.82 - 59.98 FPS Percentage under 60 FPS: 88.09523809523809% Percentage under 55 FPS: 61.904761904761905% Percentage under 50 FPS: 45.23809523809524% Percentage under 45 FPS: 35.714285714285715% Percentage under 40 FPS: 33.33333333333333% Percentage under 35 FPS: 19.047619047619047% Percentage under 30 FPS: 7.142857142857142% Percentage under 25 FPS: 4.761904761904762% Tested-by: Lyude Paul <lyude@xxxxxxxxxx> -Chris _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
