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drm/i915: Don't set queue_priority_hint if we don't kick the submission

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If we change the priority of the active context, then it has no impact
on the decision of whether to preempt the active context -- we don't
preempt the context with itself. In this situation, we elide the tasklet
rescheduling and should *not* be marking up the queue_priority_hint as
that may mask a later submission where we decide we don't have to kick
the tasklet as a higher priority submission is pending (spoiler alert,
it was not).

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191021080226.537-1-chris@chris-wilson.co.uk
This commit is contained in:
Chris Wilson 2019-10-21 09:02:11 +01:00
parent ce53908bba
commit 13ed13a4dc
1 changed files with 22 additions and 15 deletions
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37
drivers/gpu/drm/i915/i915_scheduler.c
View file

@ -189,22 +189,34 @@ static inline bool need_preempt(int prio, int active)
return prio >= max(I915_PRIORITY_NORMAL, active);
}
static void kick_submission(struct intel_engine_cs *engine, int prio)
static void kick_submission(struct intel_engine_cs *engine,
const struct i915_request *rq,
int prio)
{
const struct i915_request *inflight =
execlists_active(&engine->execlists);
const struct i915_request *inflight;
/*
* We only need to kick the tasklet once for the high priority
* new context we add into the queue.
*/
if (prio <= engine->execlists.queue_priority_hint)
return;
/* Nothing currently active? We're overdue for a submission! */
inflight = execlists_active(&engine->execlists);
if (!inflight)
return;
/*
* If we are already the currently executing context, don't
* bother evaluating if we should preempt ourselves, or if
* we expect nothing to change as a result of running the
* tasklet, i.e. we have not change the priority queue
* sufficiently to oust the running context.
* bother evaluating if we should preempt ourselves.
*/
if (!inflight || !need_preempt(prio, rq_prio(inflight)))
if (inflight->hw_context == rq->hw_context)
return;
tasklet_hi_schedule(&engine->execlists.tasklet);
engine->execlists.queue_priority_hint = prio;
if (need_preempt(prio, rq_prio(inflight)))
tasklet_hi_schedule(&engine->execlists.tasklet);
}
static void __i915_schedule(struct i915_sched_node *node,
@ -330,13 +342,8 @@ static void __i915_schedule(struct i915_sched_node *node,
list_move_tail(&node->link, cache.priolist);
}
if (prio <= engine->execlists.queue_priority_hint)
continue;
engine->execlists.queue_priority_hint = prio;
/* Defer (tasklet) submission until after all of our updates. */
kick_submission(engine, prio);
kick_submission(engine, node_to_request(node), prio);
}
spin_unlock(&engine->active.lock);