On Fri, 8 Apr 2022 at 18:25, Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxxxxxxxx> wrote: > > > On 08/04/2022 08:58, Daniel Vetter wrote: > > On Thu, Apr 07, 2022 at 04:16:27PM +0100, Tvrtko Ursulin wrote: > >> From: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx> > >> > >> Inherit submitter nice at point of request submission to account for long > >> running processes getting either externally or self re-niced. > >> > >> This accounts for the current processing landscape where computational > >> pipelines are composed of CPU and GPU parts working in tandem. > >> > >> Nice value will only apply to requests which originate from user contexts > >> and have default context priority. This is to avoid disturbing any > >> application made choices of low and high (batch processing and latency > >> sensitive compositing). In this case nice value adjusts the effective > >> priority in the narrow band of -19 to +20 around > >> I915_CONTEXT_DEFAULT_PRIORITY. > >> > >> This means that userspace using the context priority uapi directly has a > >> wider range of possible adjustments (in practice that only applies to > >> execlists platforms - with GuC there are only three priority buckets), but > >> in all cases nice adjustment has the expected effect: positive nice > >> lowering the scheduling priority and negative nice raising it. > >> > >> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx> > > > > I don't think adding any more fancy features to i915-scheduler makes > > sense, at least not before we've cut over to drm/sched. > > Why do you think so? > > Drm/sched has at least low/normal/high priority and surely we will keep > the i915 context priority ABI. > > Then this patch is not touching the i915 scheduler at all, neither it is > fancy. > > The cover letter explains how it implements the same approach as the IO > scheduler. And it explains the reasoning and benefits. Provides an user > experience benefit today, which can easily be preserved. won't this cause uAPI divergence between execlists and GuC, like if something nices to -15 or -18 with execlists and the same with GuC it won't get the same sort of result will it? Dave.
