[Intel-gfx] [PATCH igt] igt/perf_pmu: Speed up frequency measurement

[Tvrtko Ursulin]

On 15/12/2017 17:05, Chris Wilson wrote:
> Use the normal batch_duration_ns and display the sampled frequency:
> 
> 	Frequency: min=100, max=750, boost=750 MHz
> 	Min frequency: requested 100.0, actual 100.0
> 	Max frequency: requested 755.6, actual 755.6
> 
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> ---
>   tests/perf_pmu.c | 40 +++++++++++++++++++++++++---------------
>   1 file changed, 25 insertions(+), 15 deletions(-)
> 
> diff --git a/tests/perf_pmu.c b/tests/perf_pmu.c
> index d88287c17..61ae96d9a 100644
> --- a/tests/perf_pmu.c
> +++ b/tests/perf_pmu.c
> @@ -931,9 +931,10 @@ test_interrupts(int gem_fd)
>   static void
>   test_frequency(int gem_fd)
>   {
> -	const uint64_t duration_ns = 2e9;

I think I remember why it was this long - because in the early days test 
was actually applying load, not modifying frequencies directly, so had 
to wait for the frequency to ramp up.

>   	uint32_t min_freq, max_freq, boost_freq;
> -	uint64_t min[2], max[2], start[2];
> +	uint64_t val[2], start[2];
> +	double min[2], max[2];
> +	unsigned long slept;
>   	igt_spin_t *spin;
>   	int fd, sysfs;
>   
> @@ -962,17 +963,19 @@ test_frequency(int gem_fd)
>   	igt_require(igt_sysfs_set_u32(sysfs, "gt_boost_freq_mhz", min_freq));
>   	igt_require(igt_sysfs_get_u32(sysfs, "gt_boost_freq_mhz") == min_freq);
>   
> +	gem_quiescent_gpu(gem_fd); /* Idle to be sure the change takes effect */
> +	spin = igt_spin_batch_new(gem_fd, 0, I915_EXEC_RENDER, 0);
>   	pmu_read_multi(fd, 2, start);
>   
> -	spin = igt_spin_batch_new(gem_fd, 0, I915_EXEC_RENDER, 0);
> -	igt_spin_batch_set_timeout(spin, duration_ns);
> -	gem_sync(gem_fd, spin->handle);
> +	slept = measured_usleep(batch_duration_ns / 1000);

Wouldn't it be more precise to read the pmu at this point?

> +	igt_spin_batch_end(spin);
>   
> -	pmu_read_multi(fd, 2, min);
> -	min[0] -= start[0];
> -	min[1] -= start[1];
> +	pmu_read_multi(fd, 2, val);
> +	min[0] = 1e9*(val[0] - start[0]) / slept;
> +	min[1] = 1e9*(val[1] - start[1]) / slept;
>   
>   	igt_spin_batch_free(gem_fd, spin);
> +	gem_quiescent_gpu(gem_fd); /* Don't leak busy bo into the next phase */
>   
>   	usleep(1e6);
>   
> @@ -987,17 +990,19 @@ test_frequency(int gem_fd)
>   	igt_require(igt_sysfs_set_u32(sysfs, "gt_min_freq_mhz", max_freq));
>   	igt_require(igt_sysfs_get_u32(sysfs, "gt_min_freq_mhz") == max_freq);
>   
> +	gem_quiescent_gpu(gem_fd);
> +	spin = igt_spin_batch_new(gem_fd, 0, I915_EXEC_RENDER, 0);
>   	pmu_read_multi(fd, 2, start);
>   
> -	spin = igt_spin_batch_new(gem_fd, 0, I915_EXEC_RENDER, 0);
> -	igt_spin_batch_set_timeout(spin, duration_ns);
> -	gem_sync(gem_fd, spin->handle);
> +	slept = measured_usleep(batch_duration_ns / 1000);
> +	igt_spin_batch_end(spin);
>   
> -	pmu_read_multi(fd, 2, max);
> -	max[0] -= start[0];
> -	max[1] -= start[1];
> +	pmu_read_multi(fd, 2, val);
> +	max[0] = 1e9*(val[0] - start[0]) / slept;
> +	max[1] = 1e9*(val[1] - start[1]) / slept;
>   
>   	igt_spin_batch_free(gem_fd, spin);
> +	gem_quiescent_gpu(gem_fd);

Ah I see.. only for the spin batch. Why not then gem_sync or maybe we 
should add igt_spin_batch_free_sync?

Regards,

Tvrtko

>   
>   	/*
>   	 * Restore min/max.
> @@ -1008,8 +1013,13 @@ test_frequency(int gem_fd)
>   			 min_freq, igt_sysfs_get_u32(sysfs, "gt_min_freq_mhz"));
>   	close(fd);
>   
> +	igt_info("Min frequency: requested %.1f, actual %.1f\n",
> +		 min[0], min[1]);
> +	igt_info("Max frequency: requested %.1f, actual %.1f\n",
> +		 max[0], max[1]);
>   	igt_assert(min[0] < max[0]);
> -	igt_assert(min[1] < max[1]);
> +	igt_assert(min[1] <= min[0]);
> +	igt_assert(max[1] <= max[0]);
>   }
>   
>   static bool wait_for_rc6(int fd)
>