Re: [igt-dev] [PATCH i-g-t 1/3] tests/perf_pmu: Compare against requested freq in frequency subtest

[Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>]

On 10/01/2023 19:47, Ashutosh Dixit wrote:
> After the i915 commit 95ccf312a1e4f ("drm/i915/guc/slpc: Allow SLPC to use
> efficient frequency"), FW uses the requested freq as the efficient freq
> which can exceed the max freq set. Therefore, in the "min freq" part of the
> igt@perf_pmu@frequency subtest, compare the requested freq reported by PMU
> not against the set freq but against the requested freq reported in sysfs.
> 
> v2: Remove previously added delays. GuC FW is now updated to set min/max
>      freq in top half so delays are not needed
> v3: Increase tolerance between measured and requested freq to 10% to
>      account for sporadic failures due to dynamically changing efficient
>      freq. Also document the changes in code.
> 
> Bug: https://gitlab.freedesktop.org/drm/intel/-/issues/6806
> Signed-off-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
> ---
>   tests/i915/perf_pmu.c | 12 ++++++++++--
>   1 file changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/tests/i915/perf_pmu.c b/tests/i915/perf_pmu.c
> index f363db2ba13..f9ef89fb0b3 100644
> --- a/tests/i915/perf_pmu.c
> +++ b/tests/i915/perf_pmu.c
> @@ -1546,7 +1546,7 @@ test_interrupts_sync(int gem_fd)
>   static void
>   test_frequency(int gem_fd)
>   {
> -	uint32_t min_freq, max_freq, boost_freq;
> +	uint32_t min_freq, max_freq, boost_freq, min_req;
>   	uint64_t val[2], start[2], slept;
>   	double min[2], max[2];
>   	igt_spin_t *spin;
> @@ -1587,6 +1587,7 @@ test_frequency(int gem_fd)
>   
>   	min[0] = 1e9*(val[0] - start[0]) / slept;
>   	min[1] = 1e9*(val[1] - start[1]) / slept;
> +	min_req = igt_sysfs_get_u32(sysfs, "gt_cur_freq_mhz");

So remove all of the above three igt_sysfs_set_u32 and test still passes 
right? What it is testing then?

Regards,

Tvrtko

>   
>   	igt_spin_free(gem_fd, spin);
>   	gem_quiescent_gpu(gem_fd); /* Don't leak busy bo into the next phase */
> @@ -1633,7 +1634,14 @@ test_frequency(int gem_fd)
>   	igt_info("Max frequency: requested %.1f, actual %.1f\n",
>   		 max[0], max[1]);
>   
> -	assert_within_epsilon(min[0], min_freq, tolerance);
> +	/*
> +	 * With GuC SLPC, FW uses requested freq as the efficient freq which can
> +	 * exceed the max freq. Therefore compare requested freq measured by the
> +	 * PMU not against the set freq's but against the requested freq
> +	 * reported in sysfs. Also increase the tolerance a bit to account for
> +	 * dynamically changing efficient/requested freq
> +	 */
> +	assert_within_epsilon(min[0], min_req, 0.1f);
>   	/*
>   	 * On thermally throttled devices we cannot be sure maximum frequency
>   	 * can be reached so use larger tolerance downards.