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Commit dee4a0f8 authored by Chris Wilson's avatar Chris Wilson
Browse files

drm/i915/selftests: Smoketest preemption 



Very light stress test to bombard the submission backends with a large
stream with requests of randomly assigned priorities. Preemption will be
occasionally requested, but unlikely to ever succeed! (Although we may
build a long queue of requests and so may trigger an attempt to inject a
preempt context, as we emit no batch, the arbitration window is limited
to between requests inside the ringbuffer. The likelihood of actually
causing a preemption event is therefore very small. A later variant
should try to improve the likelihood of preemption events!)

v2: Include a second pattern with more frequent preemption

Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Cc: Michał Winiarski <michal.winiarski@intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: default avatarTvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180925083205.2229-1-chris@chris-wilson.co.uk
parent e7351a84

drivers/gpu/drm/i915/selftests/intel_lrc.c

+137 −0
Original line number Diff line number Diff line
@@ -6,6 +6,7 @@ 


#include "../i915_selftest.h"

#include "igt_flush_test.h"

#include "i915_random.h"



#include "mock_context.h"
@@ -573,6 +574,141 @@ static int live_preempt_hang(void *arg) 
	return err;

}



static int random_range(struct rnd_state *rnd, int min, int max)

{

	return i915_prandom_u32_max_state(max - min, rnd) + min;

}



static int random_priority(struct rnd_state *rnd)

{

	return random_range(rnd, I915_PRIORITY_MIN, I915_PRIORITY_MAX);

}



struct preempt_smoke {

	struct drm_i915_private *i915;

	struct i915_gem_context **contexts;

	unsigned int ncontext;

	struct rnd_state prng;

};



static struct i915_gem_context *smoke_context(struct preempt_smoke *smoke)

{

	return smoke->contexts[i915_prandom_u32_max_state(smoke->ncontext,

							  &smoke->prng)];

}



static int smoke_crescendo(struct preempt_smoke *smoke)

{

	struct intel_engine_cs *engine;

	enum intel_engine_id id;

	unsigned long count;



	count = 0;

	for_each_engine(engine, smoke->i915, id) {

		IGT_TIMEOUT(end_time);



		do {

			struct i915_gem_context *ctx = smoke_context(smoke);

			struct i915_request *rq;



			ctx->sched.priority = count % I915_PRIORITY_MAX;



			rq = i915_request_alloc(engine, ctx);

			if (IS_ERR(rq))

				return PTR_ERR(rq);



			i915_request_add(rq);

			count++;

		} while (!__igt_timeout(end_time, NULL));

	}



	pr_info("Submitted %lu crescendo requests across %d engines and %d contexts\n",

		count, INTEL_INFO(smoke->i915)->num_rings, smoke->ncontext);

	return 0;

}



static int smoke_random(struct preempt_smoke *smoke)

{

	struct intel_engine_cs *engine;

	enum intel_engine_id id;

	IGT_TIMEOUT(end_time);

	unsigned long count;



	count = 0;

	do {

		for_each_engine(engine, smoke->i915, id) {

			struct i915_gem_context *ctx = smoke_context(smoke);

			struct i915_request *rq;



			ctx->sched.priority = random_priority(&smoke->prng);



			rq = i915_request_alloc(engine, ctx);

			if (IS_ERR(rq))

				return PTR_ERR(rq);



			i915_request_add(rq);

			count++;

		}

	} while (!__igt_timeout(end_time, NULL));



	pr_info("Submitted %lu random requests across %d engines and %d contexts\n",

		count, INTEL_INFO(smoke->i915)->num_rings, smoke->ncontext);

	return 0;

}



static int live_preempt_smoke(void *arg)

{

	struct preempt_smoke smoke = {

		.i915 = arg,

		.prng = I915_RND_STATE_INITIALIZER(i915_selftest.random_seed),

		.ncontext = 1024,

	};

	int err = -ENOMEM;

	int n;



	if (!HAS_LOGICAL_RING_PREEMPTION(smoke.i915))

		return 0;



	smoke.contexts = kmalloc_array(smoke.ncontext,

				       sizeof(*smoke.contexts),

				       GFP_KERNEL);

	if (!smoke.contexts)

		return -ENOMEM;



	mutex_lock(&smoke.i915->drm.struct_mutex);

	intel_runtime_pm_get(smoke.i915);



	for (n = 0; n < smoke.ncontext; n++) {

		smoke.contexts[n] = kernel_context(smoke.i915);

		if (!smoke.contexts[n])

			goto err_ctx;

	}



	err = smoke_crescendo(&smoke);

	if (err)

		goto err_ctx;



	err = smoke_random(&smoke);

	if (err)

		goto err_ctx;



err_ctx:

	if (igt_flush_test(smoke.i915, I915_WAIT_LOCKED))

		err = -EIO;



	for (n = 0; n < smoke.ncontext; n++) {

		if (!smoke.contexts[n])

			break;

		kernel_context_close(smoke.contexts[n]);

	}



	intel_runtime_pm_put(smoke.i915);

	mutex_unlock(&smoke.i915->drm.struct_mutex);

	kfree(smoke.contexts);



	return err;

}



int intel_execlists_live_selftests(struct drm_i915_private *i915)

{

	static const struct i915_subtest tests[] = {
@@ -580,6 +716,7 @@ int intel_execlists_live_selftests(struct drm_i915_private *i915) 
		SUBTEST(live_preempt),

		SUBTEST(live_late_preempt),

		SUBTEST(live_preempt_hang),

		SUBTEST(live_preempt_smoke),

	};



	if (!HAS_EXECLISTS(i915))