[Intel-gfx] [CI] drm/i915/pmu: Do not assume fixed hrtimer period

[Tvrtko Ursulin]

On 05/06/2018 15:20, Chris Wilson wrote:
> Quoting Tvrtko Ursulin (2018-06-05 15:02:53)
>> From: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
>>
>> As Chris has discovered on his Ivybridge, and later automated test runs
>> have confirmed, on most of our platforms hrtimer faced with heavy GPU load
>> can occasionally become sufficiently imprecise to affect PMU sampling
>> calculations.
>>
>> This means we cannot assume sampling frequency is what we asked for, but
>> we need to measure the interval ourselves.
>>
>> This patch is similar to Chris' original proposal for per-engine counters,
>> but instead of introducing a new set to work around the problem with
>> frequency sampling, it swaps around the way internal frequency accounting
>> is done. Instead of accumulating current frequency and dividing by
>> sampling frequency on readout, it accumulates frequency scaled by each
>> period.
>>
>> v2:
>>   * Typo in commit message, comment on period calculation and USER_PER_SEC.
>>     (Chris Wilson)
> 
> Ironic typo in pointing out the typo?
> 
> /me can't tell if it's humour or just an annoying user.

More typos? Where? Don't see anything and neither does my spellchecker! :)

Regards,

Tvrtko