linux-kernel - Re: [PATCH] sched/fair: Remove idle

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Message-ID: <52FA4663.60806@linaro.org>
Date:	Tue, 11 Feb 2014 16:48:51 +0100
From:	Daniel Lezcano <daniel.lezcano@...aro.org>
To:	Peter Zijlstra <peterz@...radead.org>
CC:	mingo@...nel.org, linux-kernel@...r.kernel.org,
	Vincent Guittot <vincent.guittot@...aro.org>
Subject: Re: [PATCH] sched/fair: Remove idle_balance() declaration in sched.h

On 02/11/2014 04:46 PM, Peter Zijlstra wrote:
> On Tue, Feb 11, 2014 at 04:33:40PM +0100, Daniel Lezcano wrote:
>> On 02/11/2014 04:11 PM, Peter Zijlstra wrote:
>>> On Tue, Feb 11, 2014 at 04:01:04PM +0100, Daniel Lezcano wrote:
>>>> The idle_balance() function is called within a #ifdef CONFIG_SMP section.
>>>>
>>>> Remove its declaration in sched.h for !CONFIG_SMP because it is pointless.
>>>>
>>>> Signed-off-by: Daniel Lezcano <daniel.lezcano@...aro.org>
>>>
>>> The below again makes a horrible mess of idle_balance() -- which you
>>> tried to clean up.. but it does rid us of some #ifdef goo.
>>>
>>> Hmmm?
>>
>> Yes, it sounds ok.
>>
>> Why is idle_enter_fair() called unconditionally in idle_balance() ?
>> Isn't the call in pick_next_task_idle enough ?  Shouldn't be called when we
>> will go to idle effectively ?
>>
>> If I am not wrong idle_enter_fair() is called from idle_balance() but a task
>> may be pulled, so we the next task won't be the idle task and idle_exit_fair
>> won't be called at put_prev_task.
>>
>> May be I missed this change which was done at purpose in the previous
>> patchset you sent...
>
> lkml.kernel.org/r/CAKfTPtAMmhq0tBpu+pk_uzwrfUM-6Fz4Do1yrzc4NRQS4cZ_-A@...l.gmail.com
>
> I seem to be terminally confused on the subject, but Vincent explains it
> there I think.

Ok, thanks. I will read again the thread carefully.

   -- Daniel


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