linux-kernel - Re: [PATCH] sched/fair: Care divide error in update_task_scan

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Message-ID: <54361AD2.1040307@jp.fujitsu.com>
Date:	Thu, 9 Oct 2014 14:19:14 +0900
From:	Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>
To:	Rik van Riel <riel@...hat.com>
CC:	Peter Zijlstra <peterz@...radead.org>, <mingo@...hat.com>,
	<linux-kernel@...r.kernel.org>, <tkhai@...dex.ru>
Subject: Re: [PATCH] sched/fair: Care divide error in update_task_scan_period()

(2014/10/09 1:54), Peter Zijlstra wrote:
> On Wed, Oct 08, 2014 at 12:42:24PM -0400, Rik van Riel wrote:
>> On 10/08/2014 02:43 AM, Yasuaki Ishimatsu wrote:
>>
>>>    The divide error is rare case because the trigger is node offline.
>>>    By this patch, when both of private and shared are set to 0, diff
>>>    is just set to 0, not calculating the division.
>>
>> How about a simple
>>
>>      if (private + shared) == 0)
>>            return;
>>
>> higher up in the function, to avoid adding an extra
>> layer of indentation and confusion to the main part
>> of the function?
>
> At which point we'll have 3 different return semantics. Should we not
> clear numa_faults_localityp[], even in this case?
>

I'm not familiar with Numa balancing feature. So I want to know it too.
If it's not necessary to clear numa_faults_locality[], I'll apply the idea.

Thanks,
Yasuaki Ishimatsu

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