linux-kernel - Re: [question] sched: idle

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Wed, 11 Dec 2013 09:25:56 +0800
From:	Alex Shi <alex.shi@...aro.org>
To:	Daniel Lezcano <daniel.lezcano@...aro.org>,
	Mike Galbraith <bitbucket@...ine.de>
CC:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...nel.org>
Subject: Re: [question] sched: idle_avg and migration latency

On 12/11/2013 02:31 AM, Daniel Lezcano wrote:
>>
>> That has changed a little recently.  I originally slammed avg_idle
>> itself straight to max to ensure that a bursty load would idle balance,
>> and not use stale data.  If you start cross core switching at high
>> frequency, you'll still shut idle balancing quickly.
> 
> Ok, thanks for the explanation.
> 
> I think I am a bit puzzled with the 'idle_avg' name. I am guessing the
> semantic of this variable is "how long this cpu has been idle".
> 
> The idle duration, with the no_hz, could be long, several seconds if the
> work queues have been migrated and if the timer affinity is set to
> another cpu. So if we fall in this case and there is a burst of activity
> + micro-idle and idle_avg is not leverage to max, it will stay high
> during an amount of time, thus pulling tasks at each micro idle period,
> right ?

yes, I think so.

-- 
Thanks
    Alex
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/