[Intel-gfx] [PATCH igt 2/5] igt/perf_pmu: Tighten measurements for most-busy

[Tvrtko Ursulin]

On 22/12/2017 11:03, Chris Wilson wrote:
> Create all the spinners before starting the sampler and then measure how
> long we sleep.
> 
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=104160
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> ---
>   tests/perf_pmu.c | 45 +++++++++++++++++++++++++--------------------
>   1 file changed, 25 insertions(+), 20 deletions(-)
> 
> diff --git a/tests/perf_pmu.c b/tests/perf_pmu.c
> index 38fd05dc9..96091b853 100644
> --- a/tests/perf_pmu.c
> +++ b/tests/perf_pmu.c
> @@ -228,53 +228,58 @@ most_busy_check_all(int gem_fd, const struct intel_execution_engine2 *e,
>   	const struct intel_execution_engine2 *e_;
>   	uint64_t val[num_engines];
>   	int fd[num_engines];
> -	igt_spin_t *spin[num_engines];
> +	unsigned long slept;
> +	igt_spin_t *spin = NULL;
>   	unsigned int idle_idx, i;
>   
>   	gem_require_engine(gem_fd, e->class, e->instance);
>   
>   	i = 0;
> -	fd[0] = -1;
>   	for_each_engine_class_instance(fd, e_) {
>   		if (!gem_has_engine(gem_fd, e_->class, e_->instance))
>   			continue;
>   
> -		fd[i] = open_group(I915_PMU_ENGINE_BUSY(e_->class,
> -							e_->instance),
> -				   fd[0]);
> -
>   		if (e == e_) {
>   			idle_idx = i;
> +		} else if (spin) {
> +			struct drm_i915_gem_exec_object2 obj = {
> +				.handle = spin->handle
> +			};
> +			struct drm_i915_gem_execbuffer2 eb = {
> +				.buffer_count = 1,
> +				.buffers_ptr = to_user_pointer(&obj),
> +				.flags = e2ring(gem_fd, e_),
> +			};
> +			gem_execbuf(gem_fd, &eb);

Evil.

>   		} else {
> -			spin[i] = igt_spin_batch_new(gem_fd, 0,
> -						     e2ring(gem_fd, e_), 0);
> -			igt_spin_batch_set_timeout(spin[i], batch_duration_ns);
> +			spin = igt_spin_batch_new(gem_fd, 0,
> +						  e2ring(gem_fd, e_), 0);
>   		}
>   
> -		i++;
> +		val[i++] = I915_PMU_ENGINE_BUSY(e_->class, e_->instance);
>   	}
> +	igt_assert(i == num_engines);
>   
> -	for (i = 0; i < num_engines; i++) {
> -		if (i != idle_idx)
> -			gem_sync(gem_fd, spin[i]->handle);
> -	}
> +	fd[0] = -1;
> +	for (i = 0; i < num_engines; i++)
> +		fd[i] = open_group(val[i], fd[0]);
> +
> +	slept = measured_usleep(batch_duration_ns / 1000);
> +	igt_spin_batch_end(spin);
>   
>   	pmu_read_multi(fd[0], num_engines, val);
>   	log_busy(fd[0], num_engines, val);
>   
> -	for (i = 0; i < num_engines; i++) {
> -		if (i != idle_idx)
> -			igt_spin_batch_free(gem_fd, spin[i]);
> -	}
> +	igt_spin_batch_free(gem_fd, spin);
>   	close(fd[0]);
>   
>   	for (i = 0; i < num_engines; i++) {
>   		if (i == idle_idx)
>   			assert_within_epsilon(val[i], 0.0f, tolerance);
>   		else
> -			assert_within_epsilon(val[i], batch_duration_ns,
> -					      tolerance);
> +			assert_within_epsilon(val[i], slept, tolerance);
>   	}
> +	gem_quiescent_gpu(gem_fd);
>   }
>   
>   static void
> 

Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>

Regards,

Tvrtko