From: Rakib Mullick <rakib.mullick@gmail.com>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: linux-kernel@vger.kernel.org, kosaki.motohiro@gmail.com, mingo@elte.hu
Subject: Re: [tip:sched/urgent] sched: Fix rq->nr_uninterruptible update race
Date: Fri, 27 Jan 2012 20:11:15 +0600 [thread overview]
Message-ID: <CADZ9YHiG56TCORVySHYjnhLBSsVi=OaMRmBq-_3yDTQCGnEbYw@mail.gmail.com> (raw)
In-Reply-To: <1327652393.2446.126.camel@twins>
On Fri, Jan 27, 2012 at 2:19 PM, Peter Zijlstra <a.p.zijlstra@chello.nl> wrote:
> On Fri, 2012-01-27 at 11:20 +0600, Rakib Mullick wrote:
>> On Fri, Jan 27, 2012 at 2:25 AM, tip-bot for Peter Zijlstra
>> <a.p.zijlstra@chello.nl> wrote:
>> Why would we want to avoid nr_uninterruptible accounting?
>> nr_uninterruptible has impact on load calculation, we might not get
>> the proper load weight if we don't account it. isn't it?
>
> Read again ;-)
>
Wasn't enough! I had to use paper and pen ;-)
> sched_setscheduler() did:
>
> deactivate_task(); // remove it from the queue
>
> // change tasks's scheduler paramater
>
> activate_task(); // queue it in the new place
>
> it is invariant wrt nr_uninterruptible but does include the
> nr_uinterruptile accounting logic.
>
> Now Kosaki-San noticed that if the task manages to change its ->state at
> an inopportune moment (right between the dequeue and enqueue) we'll get
> screwy nr_uninterruptible accounting.
I got your point and yes, we'll get screwy nr_uninterruptible
accounting if we call {activate,deactivate}_task(). We need to avoid
nr_uninterruptible accounting.
Thanks,
Rakib
next prev parent reply other threads:[~2012-01-27 14:11 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-22 0:42 [BUG] TASK_DEAD task is able to be woken up in special condition Yasunori Goto
2011-12-22 2:14 ` KOSAKI Motohiro
2011-12-22 8:22 ` Yasunori Goto
2011-12-22 20:02 ` KOSAKI Motohiro
2011-12-23 9:49 ` Peter Zijlstra
2011-12-23 15:41 ` Oleg Nesterov
2011-12-26 8:23 ` Yasunori Goto
2011-12-26 17:11 ` Oleg Nesterov
2011-12-27 6:48 ` Yasunori Goto
2012-01-06 10:22 ` Yasunori Goto
2012-01-06 11:01 ` Peter Zijlstra
2012-01-06 12:01 ` Yasunori Goto
2012-01-06 12:43 ` Peter Zijlstra
2012-01-06 14:12 ` Oleg Nesterov
2012-01-06 14:19 ` Oleg Nesterov
2012-01-07 1:31 ` Yasunori Goto
2012-01-16 11:51 ` Yasunori Goto
2012-01-16 13:38 ` Peter Zijlstra
2012-01-17 8:40 ` Yasunori Goto
2012-01-17 9:06 ` Ingo Molnar
2012-01-17 15:12 ` Oleg Nesterov
2012-01-18 9:42 ` Ingo Molnar
2012-01-18 14:20 ` Oleg Nesterov
2012-01-24 10:19 ` Peter Zijlstra
2012-01-24 10:55 ` Peter Zijlstra
2012-01-24 17:25 ` KOSAKI Motohiro
2012-01-25 15:45 ` Oleg Nesterov
2012-01-25 16:51 ` Peter Zijlstra
2012-01-25 17:43 ` Oleg Nesterov
2012-01-26 15:32 ` Peter Zijlstra
2012-01-26 16:26 ` Oleg Nesterov
2012-01-27 8:59 ` Peter Zijlstra
2012-01-24 10:11 ` Peter Zijlstra
2012-01-26 9:39 ` Ingo Molnar
2012-01-28 12:03 ` [tip:sched/core] sched: Fix ancient race in do_exit() tip-bot for Yasunori Goto
2012-01-28 21:12 ` Linus Torvalds
2012-01-29 16:07 ` Oleg Nesterov
2012-01-29 17:44 ` Linus Torvalds
2012-01-29 18:28 ` Linus Torvalds
2012-01-29 18:59 ` Oleg Nesterov
2012-01-30 16:27 ` Linus Torvalds
2012-01-06 13:48 ` [BUG] TASK_DEAD task is able to be woken up in special condition Oleg Nesterov
2011-12-28 21:07 ` KOSAKI Motohiro
2012-01-24 10:23 ` Peter Zijlstra
2012-01-24 18:01 ` KOSAKI Motohiro
2012-01-25 6:15 ` Mike Galbraith
2012-01-26 21:24 ` KOSAKI Motohiro
2012-01-25 10:10 ` Peter Zijlstra
2012-01-26 20:25 ` [tip:sched/urgent] sched: Fix rq->nr_uninterruptible update race tip-bot for Peter Zijlstra
2012-01-27 5:20 ` Rakib Mullick
2012-01-27 8:19 ` Peter Zijlstra
2012-01-27 14:11 ` Rakib Mullick [this message]
2012-01-26 21:21 ` [BUG] TASK_DEAD task is able to be woken up in special condition KOSAKI Motohiro
2012-01-27 8:21 ` Peter Zijlstra
2011-12-26 6:52 ` Yasunori Goto
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