Re: [PATCH 50/51] drm/i915/guc: Implement GuC priority management

[Matthew Brost <matthew.brost@intel.com>]

On Thu, Jul 22, 2021 at 02:50:24PM -0700, Daniele Ceraolo Spurio wrote:
> 
> <snip>
> 
> > > > @@ -1756,15 +1796,119 @@ static int guc_context_alloc(struct intel_context *ce)
> > > >    	return lrc_alloc(ce, ce->engine);
> > > >    }
> > > > +static void guc_context_set_prio(struct intel_guc *guc,
> > > > +				 struct intel_context *ce,
> > > > +				 u8 prio)
> > > > +{
> > > > +	u32 action[] = {
> > > > +		INTEL_GUC_ACTION_SET_CONTEXT_PRIORITY,
> > > > +		ce->guc_id,
> > > > +		prio,
> > > > +	};
> > > > +
> > > > +	GEM_BUG_ON(prio < GUC_CLIENT_PRIORITY_KMD_HIGH ||
> > > > +		   prio > GUC_CLIENT_PRIORITY_NORMAL);
> > > > +
> > > > +	if (ce->guc_prio == prio || submission_disabled(guc) ||
> > > > +	    !context_registered(ce))
> > > > +		return;
> > > > +
> > > > +	guc_submission_send_busy_loop(guc, action, ARRAY_SIZE(action), 0, true);
> > > > +
> > > > +	ce->guc_prio = prio;
> > > > +	trace_intel_context_set_prio(ce);
> > > > +}
> > > > +
> > > > +static inline u8 map_i915_prio_to_guc_prio(int prio)
> > > > +{
> > > > +	if (prio == I915_PRIORITY_NORMAL)
> > > > +		return GUC_CLIENT_PRIORITY_KMD_NORMAL;
> > > > +	else if (prio < I915_PRIORITY_NORMAL)
> > > > +		return GUC_CLIENT_PRIORITY_NORMAL;
> > > > +	else if (prio != I915_PRIORITY_BARRIER)
> > > Shouldn't this be I915_PRIORITY_UNPREEMPTABLE?
> > > 
> > No, I915_PRIORITY_UNPREEMPTABLE is an execlists only concept.
> 
> then we need a
> 
> /* we don't expect umpreemptable submissions with the GuC */
> GEM_BUG_ON(prio == I915_PRIORITY_UNPREEMPTABLE)
> 

Actually this probably should < I915_PRIORITY_DISPLAY as we really want
pageflips to be high than any user context.

Matt

> or something, because that prio level would be assigned incorrectly
> otherwise.
> 
> Daniele
>