Hi Daniel,
On 01/28/2014 02:16 PM, Daniel Lezcano wrote:
> On 01/24/2014 11:21 AM, Preeti U Murthy wrote:
>> On 01/24/2014 02:38 PM, Daniel Lezcano wrote:
>>> On 01/23/2014 12:15 PM, Preeti U Murthy wrote:
>>>> Hi Daniel,
>>>>
>>>> Thank you for the review.
>
> [ ... ]
>
>>>> ---
>>>> drivers/cpuidle/cpuidle.c | 15 +++++
>>>> drivers/cpuidle/governors/ladder.c | 101
>>>> ++++++++++++++++++++++++++----------
>>>> drivers/cpuidle/governors/menu.c | 7 +-
>>>> 3 files changed, 90 insertions(+), 33 deletions(-)
>>>>
>>>> diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
>>>> index a55e68f..19d17e8 100644
>>>> --- a/drivers/cpuidle/cpuidle.c
>>>> +++ b/drivers/cpuidle/cpuidle.c
>>>> @@ -131,8 +131,9 @@ int cpuidle_idle_call(void)
>>>>
>>>> /* ask the governor for the next state */
>>>> next_state = cpuidle_curr_governor->select(drv, dev);
>>>> +
>>>> + dev->last_residency = 0;
>>>> if (need_resched()) {
>>>
>>> What about if (need_resched() || next_state < 0) ?
>>
>> Hmm.. I feel we need to distinguish between the need_resched() scenario
>> and the scenario when no idle state was suitable through the trace
>> points at-least.
>
> Well, I don't think so as soon as we don't care about the return value
> of cpuidle_idle_call in both cases.
>
> The traces are following a specific format. That is if the state is -1
> (PWR_EVENT_EXIT), it means exiting the current idle state.
>
> The idlestat tool [1] is using this traces to open - close transitions.
>
> IMO, if the cpu is not entering idle, it should just exit without any
> idle traces.
Yes I see your point here.
>
> This portion of code is a bit confusing because it is introduced by the
> menu governor updates post-poned when entering the next idle state (not
> exiting the current idle state with good reasons).
I am sorry but I don't understand this part. Which is the portion of the
code you refer to here? Also can you please elaborate on the above
statement?
Thanks
Regards
Preeti U Murthy
>
> -- Daniel
>
> [1] http://git.linaro.org/power/idlestat.git
>
>> This could help while debugging when we could find situations where
>> there are no tasks to run, yet the cpu is not entering any idle state.
>> The traces could help clearly point that no idle state was thought
>> suitable by the governor. Of course there are many other means to find
>> this out, but this seems rather straightforward. Hence having the
>> condition next_state < 0 between trace_cpu_idle*() would be apt IMHO.
>>
>> Regards
>> Preeti U Murthy
>>
>>>
>>>> - dev->last_residency = 0;
>>>> /* give the governor an opportunity to reflect on the
>>>> outcome */
>>>> if (cpuidle_curr_governor->reflect)
>>>> cpuidle_curr_governor->reflect(dev, next_state);
>>>> @@ -141,6 +142,16 @@ int cpuidle_idle_call(void)
>>>> }
>>>>
>>>> trace_cpu_idle_rcuidle(next_state, dev->cpu);
>>>> + /*
>>>> + * NOTE: The return code should still be success, since the
>>>> verdict of
>>>> + * this call is "do not enter any idle state". It is not a failed
>>>> call
>>>> + * due to errors.
>>>> + */
>>>> + if (next_state < 0) {
>>>> + entered_state = next_state;
>>>> + local_irq_enable();
>>>> + goto out;
>>>> + }
>>>>
>>>> broadcast = !!(drv->states[next_state].flags &
>>>> CPUIDLE_FLAG_TIMER_STOP);
>>>>
>>>> @@ -156,7 +167,7 @@ int cpuidle_idle_call(void)
>>>> if (broadcast)
>>>> clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT,
>>>> &dev->cpu);
>>>>
>>>> - trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, dev->cpu);
>>>> +out: trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, dev->cpu);
>>>>
>>>> /* give the governor an opportunity to reflect on the outcome */
>>>> if (cpuidle_curr_governor->reflect)
>>
>
>
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