Re: [igt-dev] [Intel-gfx] [PATCH i-g-t v6] tests/perf_pmu: Verify engine busyness accuracy

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

On 17/02/2018 11:36, Chris Wilson wrote:
> Quoting Tvrtko Ursulin (2018-02-15 15:34:53)
>> From: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
>>
>> A subtest to verify that the engine busyness is reported with expected
>> accuracy on platforms where the feature is available.
>>
>> We test three patterns: 2%, 50% and 98% load per engine.
>>
>> v2:
>>   * Use spin batch instead of nop calibration.
>>   * Various tweaks.
>>
>> v3:
>>   * Change loops to be time based.
>>   * Use __igt_spin_batch_new inside timing sensitive loops.
>>   * Fixed PWM sleep handling.
>>
>> v4:
>>   * Use restarting spin batch.
>>   * Calibrate more carefully by looking at the real PWM loop.
>>
>> v5:
>>   * Made standalone.
>>   * Better info messages.
>>   * Tweak sleep compensation.
>>
>> v6:
>>   * Some final tweaks. (Chris Wilson)
>>
>> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
>> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
>> ---
>> +
>> +       /* Sampling platforms cannot reach the high accuracy criteria. */
>> +       igt_require(gem_has_execlists(gem_fd));
> 
> But we don't handle guc, right?

Correct.

> igt_skip_on(gem_has_guc_submission(gem_fd)) ?

I'll dig up and rebase my old patch which implements busy stats in GuC 
mode.

> https://intel-gfx-ci.01.org/tree/drm-tip/kasan_2/fi-skl-guc/igt@perf_pmu@busy-accuracy-2-vecs0.html
> 
> Or at least it doesn't work to sufficient accuracy. And bsw hung.

There are some occasional excursions over 15% tolerance even with 
execlists on small core. Bummer. Don't want to be playing up the 
tolerance game. I'll analyse in more detail and think what to do.

Do you have a link to BSW hang? Is that obviously related to PMU?

Regards,

Tvrtko


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