Quoting Chris Wilson (2019-09-20 17:03:34) > Quoting Bloomfield, Jon (2019-09-20 16:50:57) > > > -----Original Message----- > > > From: Intel-gfx <intel-gfx-bounces@xxxxxxxxxxxxxxxxxxxxx> On Behalf Of Tvrtko > > > Ursulin > > > Sent: Friday, September 20, 2019 8:12 AM > > > To: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>; intel-gfx@xxxxxxxxxxxxxxxxxxxxx > > > Subject: Re: [PATCH] drm/i915: Prevent bonded requests from > > > overtaking each other on preemption > > > > > > > > > On 20/09/2019 15:57, Chris Wilson wrote: > > > > Quoting Chris Wilson (2019-09-20 09:36:24) > > > >> Force bonded requests to run on distinct engines so that they cannot be > > > >> shuffled onto the same engine where timeslicing will reverse the order. > > > >> A bonded request will often wait on a semaphore signaled by its master, > > > >> creating an implicit dependency -- if we ignore that implicit dependency > > > >> and allow the bonded request to run on the same engine and before its > > > >> master, we will cause a GPU hang. > > > > > > > > Thinking more, it should not directly cause a GPU hang, as the stuck request > > > > should be timesliced away, and each preemption should be enough to keep > > > > hangcheck at bay (though we have evidence it may not). So at best it runs > > > > at half-speed, at worst a third (if my model is correct). > > > > > > But I think it is still correct to do since we don't have the coupling > > > information on re-submit. Hm.. but don't we need to prevent slave from > > > changing engines as well? > > > > Unless I'm missing something, the proposal here is to set the engines in stone at first submission, and never change them? > > For submission here, think execution (submission to actual HW). (We have > 2 separate phases that all like to be called submit()!) s/2/3/ -Chris _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
