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From: Tejun Heo <tj@kernel.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: mingo@elte.hu, linux-kernel@vger.kernel.org,
	Rusty Russell <rusty@rustcorp.com.au>,
	Mike Galbraith <efault@gmx.de>
Subject: Re: [PATCH 2/4] sched: implement __set_cpus_allowed()
Date: Mon, 31 May 2010 12:06:00 +0200	[thread overview]
Message-ID: <4C038A08.8090209@kernel.org> (raw)
In-Reply-To: <1275300165.27810.21858.camel@twins>

On 05/31/2010 12:02 PM, Peter Zijlstra wrote:
> On Mon, 2010-05-31 at 12:01 +0200, Peter Zijlstra wrote:
>>>  but we can update cpu_active mask before other
>>> CPU_UP_PREPARE notifiers are executed so that it's symmetrical to cpu
>>> down path and then this problem goes away the exact same way, right?
>>
>> Ah, no, we cannot mark it active before its actually up, because at that
>> time we'll actually try and run stuff on it, which clearly won't work
>> when its not there to run stuff. 
> 
> So we should clear it _before_ we go down, and set it _after_ we're up.
> 

Yeah, sure, I misspoke.  I meant CPU_ONLINE not CPU_UP_PREPARE.  So,
we can mark a cpu active before other CPU_ONLINE callbacks are run.

Thanks.

-- 
tejun

  reply	other threads:[~2010-05-31 10:06 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-05-13 10:48 [PATCHSET sched/core] sched: prepare for cmwq Tejun Heo
2010-05-13 10:48 ` [PATCH 1/4] sched: consult online mask instead of active in select_fallback_rq() Tejun Heo
2010-05-31  8:01   ` Peter Zijlstra
2010-05-31  9:48     ` Tejun Heo
2010-05-13 10:48 ` [PATCH 2/4] sched: implement __set_cpus_allowed() Tejun Heo
2010-05-31  8:01   ` Peter Zijlstra
2010-05-31  9:55     ` Tejun Heo
2010-05-31 10:01       ` Peter Zijlstra
2010-05-31 10:02         ` Peter Zijlstra
2010-05-31 10:06           ` Tejun Heo [this message]
2010-05-31 10:15             ` Peter Zijlstra
2010-05-31 10:19               ` Tejun Heo
2010-05-31 10:46                 ` Peter Zijlstra
2010-05-31 11:47                   ` Tejun Heo
2010-05-13 10:48 ` [PATCH 3/4] sched: refactor try_to_wake_up() Tejun Heo
2010-05-13 10:48 ` [PATCH 4/4] sched: add hooks for workqueue Tejun Heo
2010-05-31  8:01   ` Peter Zijlstra
2010-05-31  9:58     ` Tejun Heo
2010-05-31 10:05       ` Peter Zijlstra
2010-05-31 10:07         ` Tejun Heo
2010-05-17 23:13 ` [PATCHSET sched/core] sched: prepare for cmwq Tejun Heo
2010-05-21 13:25   ` Tejun Heo
2010-05-23  9:05     ` Ingo Molnar
2010-05-23  9:08       ` Tejun Heo
2010-05-23  9:13         ` Ingo Molnar
2010-05-23  9:24           ` Tejun Heo
2010-05-23 10:20             ` Ingo Molnar
2010-05-23 10:26               ` Tejun Heo
2010-05-27  8:26                 ` Tejun Heo

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