On 06/23/2016 03:35 PM, Shreyas B Prabhu wrote:
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.
I see, the snooze exit is very fast.
Does it solve the issue if you replace >>10 by /1000 ?
Yes it does.
Ok. IMO, it would be cleaner to fix this in the core code.
-- Daniel
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