[Intel-gfx] [PATCH i-g-t 05/11] tests/perf: rework oa-exponent test

[Lionel Landwerlin]

On 22/08/17 17:13, Matthew Auld wrote:
> On 22 August 2017 at 15:56, Lionel Landwerlin
> <lionel.g.landwerlin at intel.com> wrote:
>> On 10/08/17 14:15, Matthew Auld wrote:
>>
>> On 4 August 2017 at 12:20, Lionel Landwerlin
>> <lionel.g.landwerlin at intel.com> wrote:
>>
>> New issues that were discovered while making the tests work on Gen8+ :
>>
>>   - we need to measure timings between periodic reports and discard all
>>     other kind of reports
>>
>>   - it seems periodicity of the reports can be affected outside of RC6
>>     (frequency change), we can detect this by looking at the amount of
>>     clock cycles per timestamp deltas
>>
>> I think this would be easier to review if we split this into two patches...
>>
>> Also, somewhat worrying is that I've yet to see the oa-exponents test
>> pass on my BDW machine.
>>
>> See here:
>> https://paste.fedoraproject.org/paste/SmOw7eHEGOTjrLsvPVcZOw/raw
>>
>> Was your screen off?
> I don't think so, same result with it on/off though. I'm guessing that
> is passes for you then?
>
> Here's the pastebin again, since the other one is now toast:
> https://paste.fedoraproject.org/paste/tjSb4jPZ87sWjhj7qAD~UA/raw
>
Chris helped prove that this probably be power management preventing the 
unit to write its report to memory.
I don't think there is a way to tune that from userspace, so I guess 
I'll try to detect this. It's pretty reproducible on my system with 
screen off.
Maybe you're on battery only?

-
Lionel