linux-kernel - Re: [RFC,v2 3/3] sched: ignore task_h_load for CPU_NEWLY

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Date:   Wed, 8 Mar 2017 16:35:42 +0100
From:   Uladzislau Rezki <urezki@...il.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Ingo Molnar <mingo@...hat.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Uladzislau 2 Rezki <uladzislau2.rezki@...ymobile.com>,
        Oleksiy Avramchenko <oleksiy.avramchenko@...ymobile.com>,
        Dietmar Eggemann <dietmar.eggemann@....com>
Subject: Re: [RFC,v2 3/3] sched: ignore task_h_load for CPU_NEWLY_IDLE

Hello.

Let's decide how to proceed with https://lkml.org/lkml/2017/2/14/334 patch.
Despite it is not a big change, i think it is important and ready to
be submited,
unless there are still any comments.

--
Uladzislau Rezki

On Thu, Feb 16, 2017 at 12:20 PM, Uladzislau Rezki <urezki@...il.com> wrote:
> On Wed, Feb 15, 2017 at 7:58 PM, Dietmar Eggemann
> <dietmar.eggemann@....com> wrote:
>> On 02/14/2017 06:28 PM, Uladzislau Rezki wrote:
>>>>>
>>>>>
>>>>> So that is useful information that should have been in the Changelog.
>>>>>
>>>>> OK, can you respin this patch with adjusted Changelog and taking Mike's
>>>>> feedback?
>>>>>
>>>> Yes, i will prepare a patch accordingly, no problem.
>>>>
>>>>>
>>>>> Also, I worry about the effects of this on !PREEMPT kernels, the first
>>>>> hunk (which explicitly states is about latency) should be under
>>>>> CONFIG_PREEMPT to match the similar case we already have in
>>>>> detach_tasks().
>>
>>
>> This one uses #ifdef CONFIG_PREEMPT whereas you use
>> IS_ENABLED(CONFIG_PREEMPT). Is there a particular reason for this?
>>
> I just wanted to put it under one line instead of using #ifdefs in my
> second hunk,
> so that is a matter of taste. Also, please find below different
> variants of how it can be
> rewriten:
>
> <variant 1>
> #ifdef CONFIG_PREEMPT
>     if (env->idle != CPU_NEWLY_IDLE)
> #endif
>         if ((load / 2) > env->imbalance)
>             goto next;
> <variant 1>
>
> <variant 2>
> #ifdef CONFIG_PREEMPT
>     if (env->idle != CPU_NEWLY_IDLE &&
>             (load / 2) > env->imbalance)
>         goto next;
> #else
>     if ((load / 2) > env->imbalance)
>         goto next;
> #endif
> <variant 2>
>
> If somebody has any preferences or concerns, please comment, i will
> re-spin the patch.
>
> --
> Uladzislau Rezki