Quoting Chris Wilson (2019-01-23 13:47:29) > Quoting Chris Wilson (2019-01-23 12:36:02) > > On unwinding the active request we give it a small (limited to internal > > priority levels) boost to prevent it from being gazumped a second time. > > However, this means that it can be promoted to above the request that > > triggered the preemption request, causing a preempt-to-idle cycle for no > > change. We can avoid this if we take the boost into account when > > checking if the preemption request is valid. > > > > Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > > --- > > drivers/gpu/drm/i915/intel_lrc.c | 29 +++++++++++++++++++++++++---- > > 1 file changed, 25 insertions(+), 4 deletions(-) > > > > diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c > > index d9d744f6ab2c..74726f647e47 100644 > > --- a/drivers/gpu/drm/i915/intel_lrc.c > > +++ b/drivers/gpu/drm/i915/intel_lrc.c > > @@ -163,6 +163,8 @@ > > #define WA_TAIL_DWORDS 2 > > #define WA_TAIL_BYTES (sizeof(u32) * WA_TAIL_DWORDS) > > > > +#define ACTIVE_PRIORITY (I915_PRIORITY_NEWCLIENT) > > + > > static int execlists_context_deferred_alloc(struct i915_gem_context *ctx, > > struct intel_engine_cs *engine, > > struct intel_context *ce); > > @@ -181,13 +183,31 @@ static inline int rq_prio(const struct i915_request *rq) > > return rq->sched.attr.priority; > > } > > > > +static inline int active_prio(const struct i915_request *rq) > > +{ > > + int prio = rq_prio(rq); > > + > > + /* > > + * On unwinding the active request, we give it a priority bump > > + * equivalent to a freshly submitted request. This protects it from > > + * being gazumped again, but it would be preferrable if we didn't > > + * let it be gazumped in the first place! > > + * > > + * See __unwind_incomplete_requests() > > + */ > > + if (i915_request_started(rq)) > > + prio |= ACTIVE_PRIORITY; > > Hmm, actually we are put to the tail of that priolist so we don't get > rerun ahead of the preemptee if we end up at the same priority. > ACTIVE_PRIORITY - 1 would seem to be the right compromise. gem_sync/switch-default says ACTIVE_PRIORITY though. Hmm. -Chris _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx