Commit d99f7b07 authored by Chris Wilson's avatar Chris Wilson
Browse files

drm/i915/gt: Flush submission tasklet before waiting/retiring 



A common bane of ours is arbitrary delays in ksoftirqd processing our
submission tasklet. Give the submission tasklet a kick before we wait to
avoid those delays eating into a tight timeout.

Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: default avatarStuart Summers <stuart.summers@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191008105655.13256-1-chris@chris-wilson.co.uk
parent 23b9e41a

drivers/gpu/drm/i915/gt/intel_engine.h

+2 −1
Original line number Diff line number Diff line
@@ -407,8 +407,9 @@ static inline void __intel_engine_reset(struct intel_engine_cs *engine, 
	engine->serial++; /* contexts lost */

}



bool intel_engine_is_idle(struct intel_engine_cs *engine);

bool intel_engines_are_idle(struct intel_gt *gt);

bool intel_engine_is_idle(struct intel_engine_cs *engine);

void intel_engine_flush_submission(struct intel_engine_cs *engine);



void intel_engines_reset_default_submission(struct intel_gt *gt);

drivers/gpu/drm/i915/gt/intel_engine_cs.c

+20 −13
Original line number Diff line number Diff line
@@ -1040,6 +1040,25 @@ static bool ring_is_idle(struct intel_engine_cs *engine) 
	return idle;

}



void intel_engine_flush_submission(struct intel_engine_cs *engine)

{

	struct tasklet_struct *t = &engine->execlists.tasklet;



	if (__tasklet_is_scheduled(t)) {

		local_bh_disable();

		if (tasklet_trylock(t)) {

			/* Must wait for any GPU reset in progress. */

			if (__tasklet_is_enabled(t))

				t->func(t->data);

			tasklet_unlock(t);

		}

		local_bh_enable();

	}



	/* Otherwise flush the tasklet if it was running on another cpu */

	tasklet_unlock_wait(t);

}



/**

 * intel_engine_is_idle() - Report if the engine has finished process all work

 * @engine: the intel_engine_cs
@@ -1058,21 +1077,9 @@ bool intel_engine_is_idle(struct intel_engine_cs *engine) 


	/* Waiting to drain ELSP? */

	if (execlists_active(&engine->execlists)) {

		struct tasklet_struct *t = &engine->execlists.tasklet;



		synchronize_hardirq(engine->i915->drm.pdev->irq);



		local_bh_disable();

		if (tasklet_trylock(t)) {

			/* Must wait for any GPU reset in progress. */

			if (__tasklet_is_enabled(t))

				t->func(t->data);

			tasklet_unlock(t);

		}

		local_bh_enable();



		/* Otherwise flush the tasklet if it was on another cpu */

		tasklet_unlock_wait(t);

		intel_engine_flush_submission(engine);



		if (execlists_active(&engine->execlists))

			return false;

drivers/gpu/drm/i915/gt/intel_gt_requests.c

+12 −0
Original line number Diff line number Diff line
@@ -4,6 +4,7 @@ 
 * Copyright © 2019 Intel Corporation

 */



#include "i915_drv.h" /* for_each_engine() */

#include "i915_request.h"

#include "intel_gt.h"

#include "intel_gt_pm.h"
@@ -19,6 +20,15 @@ static void retire_requests(struct intel_timeline *tl) 
			break;

}



static void flush_submission(struct intel_gt *gt)

{

	struct intel_engine_cs *engine;

	enum intel_engine_id id;



	for_each_engine(engine, gt->i915, id)

		intel_engine_flush_submission(engine);

}



long intel_gt_retire_requests_timeout(struct intel_gt *gt, long timeout)

{

	struct intel_gt_timelines *timelines = &gt->timelines;
@@ -32,6 +42,8 @@ long intel_gt_retire_requests_timeout(struct intel_gt *gt, long timeout) 
	if (unlikely(timeout < 0))

		timeout = -timeout, interruptible = false;



	flush_submission(gt); /* kick the ksoftirqd tasklets */



	spin_lock_irqsave(&timelines->lock, flags);

	list_for_each_entry_safe(tl, tn, &timelines->active_list, link) {

		if (!mutex_trylock(&tl->mutex)) {

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