Re: [Intel-gfx] [PATCH] drm/i915/selftests: Add request throughput measurement to perf

[Andi Shyti <andi@etezian.org>]

Hi Chris,

[...]

> +static int s_many(void *arg)
> +{
> +	struct perf_series *ps = arg;

why do we need to go through void... all functions are taking a
perf_series structure.

> +	IGT_TIMEOUT(end_time);
> +	unsigned int idx = 0;
> +

[...]

> +		for (idx = 0; idx < nengines; idx++) {
> +			struct perf_stats *p =
> +				memset(&stats[idx], 0, sizeof(stats[idx]));
> +			struct intel_context *ce = ps->ce[idx];
> +
> +			p->engine = ps->ce[idx]->engine;
> +			intel_engine_pm_get(p->engine);
> +
> +			if (intel_engine_supports_stats(p->engine) &&
> +			    !intel_enable_engine_stats(p->engine))
> +				p->busy = intel_engine_get_busy_time(p->engine) + 1;
> +			p->runtime = -intel_context_get_total_runtime_ns(ce);
> +			p->time = ktime_get();
> +		}
> +
> +		err = (*fn)(ps);
> +		if (igt_live_test_end(&t))
> +			err = -EIO;
> +
> +		for (idx = 0; idx < nengines; idx++) {
> +			struct perf_stats *p = &stats[idx];
> +			struct intel_context *ce = ps->ce[idx];
> +			int integer, decimal;
> +			u64 busy, dt;
> +
> +			p->time = ktime_sub(ktime_get(), p->time);
> +			if (p->busy) {
> +				p->busy = ktime_sub(intel_engine_get_busy_time(p->engine),
> +						    p->busy - 1);
> +				intel_disable_engine_stats(p->engine);
> +			}
> +
> +			err = switch_to_kernel_sync(ce, err);

how about err?

> +			p->runtime += intel_context_get_total_runtime_ns(ce);

assigning a negative value to an unsigned so that you can add it
later? looks nice but odd :)

It's easier to understand if we do

p->runtime = intel_context_get_total_runtime_ns(ce) - p->runtime;

if you like it, no need to change, though.

[...]

> +static int p_many(void *arg)
> +{
> +	struct perf_stats *p = arg;
> +	struct intel_engine_cs *engine = p->engine;
> +	struct intel_context *ce;
> +	IGT_TIMEOUT(end_time);
> +	unsigned long count;
> +	int err = 0;
> +	bool busy;
> +
> +	ce = intel_context_create(engine);
> +	if (IS_ERR(ce))
> +		return PTR_ERR(ce);
> +
> +	err = intel_context_pin(ce);
> +	if (err) {
> +		intel_context_put(ce);
> +		return err;
> +	}
> +
> +	busy = false;
> +	if (intel_engine_supports_stats(engine) &&
> +	    !intel_enable_engine_stats(engine)) {
> +		p->busy = intel_engine_get_busy_time(engine);
> +		busy = true;
> +	}
> +
> +	count = 0;
> +	p->time = ktime_get();
> +	do {
> +		struct i915_request *rq;
> +
> +		rq = i915_request_create(ce);
> +		if (IS_ERR(rq)) {
> +			err = PTR_ERR(rq);
> +			break;
> +		}
> +
> +		i915_request_add(rq);

do we need a request_put as well?

> +		count++;
> +	} while (!__igt_timeout(end_time, NULL));
> +	p->time = ktime_sub(ktime_get(), p->time);
> +
> +	if (busy) {
> +		p->busy = ktime_sub(intel_engine_get_busy_time(engine),
> +				    p->busy);
> +		intel_disable_engine_stats(engine);
> +	}
> +
> +	err = switch_to_kernel_sync(ce, err);
> +	p->runtime = intel_context_get_total_runtime_ns(ce);
> +	p->count = count;
> +
> +	intel_context_unpin(ce);
> +	intel_context_put(ce);
> +	return err;
> +}

[...]

> +		for_each_uabi_engine(engine, i915) {
> +			int status;
> +
> +			if (IS_ERR(engines[idx].tsk))
> +				break;

if we break here aren't we missing engine_pm_put and put_task?

Andi

> +
> +			status = kthread_stop(engines[idx].tsk);
> +			if (status && !err)
> +				err = status;
> +
> +			intel_engine_pm_put(engine);
> +			put_task_struct(engines[idx++].tsk);
> +		}
> +
> +		if (igt_live_test_end(&t))
> +			err = -EIO;
> +		if (err)
> +			break;
> +
> +		idx = 0;
> +		for_each_uabi_engine(engine, i915) {
> +			struct perf_stats *p = &engines[idx].p;
> +			u64 busy = 100 * ktime_to_ns(p->busy);
> +			u64 dt = ktime_to_ns(p->time);
> +			int integer, decimal;
> +
> +			if (dt) {
> +				integer = div64_u64(busy, dt);
> +				busy -= integer * dt;
> +				decimal = div64_u64(100 * busy, dt);
> +			} else {
> +				integer = 0;
> +				decimal = 0;
> +			}
> +
> +			GEM_BUG_ON(engine != p->engine);
> +			pr_info("%s %5s: { count:%lu, busy:%d.%02d%%, runtime:%lldms, walltime:%lldms }\n",
> +				name, engine->name, p->count, integer, decimal,
> +				div_u64(p->runtime, 1000 * 1000),
> +				div_u64(ktime_to_ns(p->time), 1000 * 1000));
> +			idx++;
> +		}
> +	}
> +
> +	cpu_latency_qos_remove_request(&qos);
> +	kfree(engines);
> +	return err;
> +}
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