On Mon, Feb 24, 2014 at 08:30:22AM +0000, Chris Wilson wrote: > On Sun, Feb 23, 2014 at 12:12:25PM -0800, Ben Widawsky wrote: > > On Mon, Aug 26, 2013 at 12:06:43PM +0100, Chris Wilson wrote: > > > Obtaining the forcwake requires expensive and time consuming > > > serialisation. And we often try to obtain the forcewake multiple times > > > in very quick succession. We can reduce the overhead of these sequences > > > by delaying the forcewake release, and so not hammer the hw quite so > > > hard. > > > > > > I was hoping this would help with the spurious > > > [drm:__gen6_gt_force_wake_mt_get] *ERROR* Timed out waiting for forcewake old ack to clear. > > > found on Haswell. Alas not. > > > > > > v2: Fix teardown ordering - unmap the regs after turning off forcewake, > > > and make sure we do turn off forcewake - both found by Ville. > > > > > > Note: I have no claims for improved performance, stablity or power > > > comsumption for this patch. We should not be hitting the registers often > > > enough for this to improve benchmarks, but given the nature of our hw it > > > is likely to improve long term stability. > > > > I don't understand how or why but from casual powertop observation, this > > workqueue uses between 4x and 50x or the nearest other i915 workqueue > > (i915_gem_retire_work_handler). On my x240... > > What does that mean? We expect this to be frequently hit since we use it > so often, but retire_work_handler is only run every couple of seconds to > trim our lists (in case of userspace failure). > > The idea is to have the forcewake reset run during the next scheduler event, > so using a workqueue was probably the wrong choice and perhaps we should have > used a timer instead? > -Chris > > -- > Chris Wilson, Intel Open Source Technology Centre I just posted it for the sake of potentially starting a conversation. I assume we always expected power consumption to go up since [it would seem at least] we're usually just deferring the release of the last put(). But then we have the race to idle argument in there as well. In any event, I wasn't asking for any change, was just surprised by the data. -- Ben Widawsky, Intel Open Source Technology Center _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
