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Commit c5ce3b8d authored by Chris Wilson's avatar Chris Wilson
Browse files

drm/i915/execlists: Don't trigger preemption if complete 



Due to the latency of the tasklet running from ksoftirqd, by the time we
process the execlist dequeue may be a long time behind the GPU. If the
request was completed when we ran reschedule, we will not have tweaked
its priority, but if it is still listed as being in-flight for dequeue
we will use it as a reference for the rest of the queue, including
requests from its own context which will now be at higher priority. This
can cause us to issue a preempt-to-idle request, even though the request
we want to preempt is already complete.

Reported-by: default avatarTvrtko Ursulin <tvrtko.ursulin@intel.com>
Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180501122131.19435-1-chris@chris-wilson.co.uk


Reviewed-by: default avatarTvrtko Ursulin <tvrtko.ursulin@intel.com>
parent 36cf89f5

drivers/gpu/drm/i915/intel_lrc.c

+2 −1
Original line number Diff line number Diff line
@@ -185,7 +185,8 @@ static inline bool need_preempt(const struct intel_engine_cs *engine, 
				int prio)

{

	return (intel_engine_has_preemption(engine) &&

		__execlists_need_preempt(prio, rq_prio(last)));

		__execlists_need_preempt(prio, rq_prio(last)) &&

		!i915_request_completed(last));

}



/**