Quoting Tvrtko Ursulin (2018-08-02 15:47:37) > > On 28/07/2018 17:46, Chris Wilson wrote: > > Here we bump the busyspin for the current request to avoid sleeping and > > the cost of both idling and downclocking the CPU. > > > > Signed-off-by: Chris Wilson <[email protected]> > > Cc: Sagar Kamble <[email protected]> > > Cc: Eero Tamminen <[email protected]> > > Cc: Francisco Jerez <[email protected]> > > Cc: Tvrtko Ursulin <[email protected]> > > Cc: Ben Widawsky <[email protected]> > > Cc: Joonas Lahtinen <[email protected]> > > Cc: Michał Winiarski <[email protected]> > > --- > > drivers/gpu/drm/i915/Kconfig.profile | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/gpu/drm/i915/Kconfig.profile > > b/drivers/gpu/drm/i915/Kconfig.profile > > index de394dea4a14..54e0ba4051e7 100644 > > --- a/drivers/gpu/drm/i915/Kconfig.profile > > +++ b/drivers/gpu/drm/i915/Kconfig.profile > > @@ -1,6 +1,6 @@ > > config DRM_I915_SPIN_REQUEST_IRQ > > int > > - default 5 # microseconds > > + default 250 # microseconds > > help > > Before sleeping waiting for a request (GPU operation) to complete, > > we may spend some time polling for its completion. As the IRQ may > > > > But the histograms from previous patch do not suggest 250us busy spin > gets us into interesting territory. And we have to know the distribution > between IRQ and CS spins.
This is for a different problem than presented in those histograms. This is to hide the reclocking that occurred if we sleep. Previous justification for the initial spin was to try and hide the irq setup costs, this is to try and hide the sleep costs. The purpose of this patch was just to dip the toe into the water of what is possible and solicit feedback since we are still waiting for the panacea patches to improve cpufreq. (Why it had such a lackluster justification.) -Chris _______________________________________________ Intel-gfx mailing list [email protected] https://lists.freedesktop.org/mailman/listinfo/intel-gfx
