On 06/23/2016 03:31 PM, Daniel Lezcano wrote:
> On 06/23/2016 11:28 AM, Balbir Singh wrote:
>
> [ ... ]
>
>>> cpuidle_enter_state()
>>> {
>>> [...]
>>> time_start = local_clock();
>>> [enter idle state]
>>> time_end = local_clock();
>>> /*
>>> * local_clock() returns the time in nanosecond, let's shift
>>> * by 10 (divide by 1024) to have microsecond based time.
>>> */
>>> diff = (time_end - time_start) >> 10;
>>> [...]
>>> dev->last_residency = (int) diff;
>>> }
>>>
>>> Because of >>10 as opposed to /1000, last_residency is lesser by 2.3%
>
> I am surprised the last_residency is 2.3% exactly less. The difference
> between >>10 and /1000 is 2.34%.
>
> What is the next target residency value ?
>
Target residency of the next idle state is 100 microseconds.
When snooze times out after 100 microseconds, last_residency value
calculated is typically 97 or 98 microseconds.
> Does it solve the issue if you replace >>10 by /1000 ?
>
Yes it does.
--Shreyas
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