Re: [PATCH] drm/i915/selftests: Exercise concurrent submission to all engines

[Mika Kuoppala <mika.kuoppala@linux.intel.com>]

Chris Wilson <chris@chris-wilson.co.uk> writes:

> The simplest and most maximal submission we can do, a thread to submit
> requests unto each engine.
>
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
> ---
>  drivers/gpu/drm/i915/selftests/i915_request.c | 125 ++++++++++++++++++
>  1 file changed, 125 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/selftests/i915_request.c b/drivers/gpu/drm/i915/selftests/i915_request.c
> index b3688543ed7d..57cd4180d06c 100644
> --- a/drivers/gpu/drm/i915/selftests/i915_request.c
> +++ b/drivers/gpu/drm/i915/selftests/i915_request.c
> @@ -1062,6 +1062,130 @@ static int live_sequential_engines(void *arg)
>  	return err;
>  }
>  
> +static int __live_parallel_engine1(void *arg)
> +{
> +	struct intel_engine_cs *engine = arg;
> +	IGT_TIMEOUT(end_time);
> +	unsigned long count;
> +
> +	count = 0;
> +	do {
> +		struct i915_request *rq;
> +		int err;
> +
> +		mutex_lock(&engine->i915->drm.struct_mutex);
> +		rq = i915_request_create(engine->kernel_context);
> +		if (IS_ERR(rq)) {
> +			mutex_unlock(&engine->i915->drm.struct_mutex);
> +			return PTR_ERR(rq);
> +		}
> +
> +		i915_request_get(rq);
> +		i915_request_add(rq);
> +		mutex_unlock(&engine->i915->drm.struct_mutex);
> +
> +		err = 0;
> +		if (i915_request_wait(rq, 0, HZ / 5) < 0)
> +			err = -ETIME;
> +		i915_request_put(rq);
> +		if (err)
> +			return err;
> +
> +		count++;
> +	} while (!__igt_timeout(end_time, NULL));
> +
> +	pr_info("%s: %lu request + sync\n", engine->name, count);
> +	return 0;
> +}
> +
> +static int __live_parallel_engineN(void *arg)
> +{
> +	struct intel_engine_cs *engine = arg;
> +	IGT_TIMEOUT(end_time);
> +	unsigned long count;
> +
> +	count = 0;
> +	do {
> +		struct i915_request *rq;
> +
> +		mutex_lock(&engine->i915->drm.struct_mutex);
> +		rq = i915_request_create(engine->kernel_context);
> +		if (IS_ERR(rq)) {
> +			mutex_unlock(&engine->i915->drm.struct_mutex);
> +			return PTR_ERR(rq);
> +		}
> +
> +		i915_request_add(rq);
> +		mutex_unlock(&engine->i915->drm.struct_mutex);
> +
> +		count++;
> +	} while (!__igt_timeout(end_time, NULL));
> +
> +	pr_info("%s: %lu requests\n", engine->name, count);
> +	return 0;
> +}
> +
> +static int live_parallel_engines(void *arg)
> +{
> +	struct drm_i915_private *i915 = arg;
> +	static int (* const func[])(void *arg) = {
> +		__live_parallel_engine1,
> +		__live_parallel_engineN,

The ratio of waited vs nonwaited ones is
now up to their competition for access which
did concern me.

But then on the other hand, due to wait,
that thread will end up with lot less
access.

So, I think in the end the pattern will
be mostly unwaited ones with a wait now
and then.

Which was kind of what I was yearning for
so,

Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>

> +		NULL,
> +	};
> +	struct intel_engine_cs *engine;
> +	enum intel_engine_id id;
> +	int (* const *fn)(void *arg);
> +	int err = 0;
> +
> +	/*
> +	 * Check we can submit requests to all engines concurrently. This
> +	 * tests that we load up the system maximally.
> +	 */
> +
> +	for (fn = func; !err && *fn; fn++) {
> +		struct task_struct *tsk[I915_NUM_ENGINES] = {};
> +		struct igt_live_test t;
> +
> +		mutex_lock(&i915->drm.struct_mutex);
> +		err = igt_live_test_begin(&t, i915, __func__, "");
> +		mutex_unlock(&i915->drm.struct_mutex);
> +		if (err)
> +			break;
> +
> +		for_each_engine(engine, i915, id) {
> +			tsk[id] = kthread_run(*fn, engine,
> +					      "igt/parallel:%s",
> +					      engine->name);
> +			if (IS_ERR(tsk[id])) {
> +				err = PTR_ERR(tsk[id]);
> +				break;
> +			}
> +			get_task_struct(tsk[id]);
> +		}
> +
> +		for_each_engine(engine, i915, id) {
> +			int status;
> +
> +			if (IS_ERR_OR_NULL(tsk[id]))
> +				continue;
> +
> +			status = kthread_stop(tsk[id]);
> +			if (status && !err)
> +				err = status;
> +
> +			put_task_struct(tsk[id]);
> +		}
> +
> +		mutex_lock(&i915->drm.struct_mutex);
> +		if (igt_live_test_end(&t))
> +			err = -EIO;
> +		mutex_unlock(&i915->drm.struct_mutex);
> +	}
> +
> +	return err;
> +}
> +
>  static int
>  max_batches(struct i915_gem_context *ctx, struct intel_engine_cs *engine)
>  {
> @@ -1240,6 +1364,7 @@ int i915_request_live_selftests(struct drm_i915_private *i915)
>  		SUBTEST(live_nop_request),
>  		SUBTEST(live_all_engines),
>  		SUBTEST(live_sequential_engines),
> +		SUBTEST(live_parallel_engines),
>  		SUBTEST(live_empty_request),
>  		SUBTEST(live_breadcrumbs_smoketest),
>  	};
> -- 
> 2.23.0
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