Subject: Re: [PATCH 04/40] sched: implement __set_cpus_allowed()
From: Peter Zijlstra <peterz@infradead.org>
To: Tejun Heo <tj@kernel.org>
Cc: torvalds@linux-foundation.org, mingo@elte.hu, awalls@radix.net,
       linux-kernel@vger.kernel.org, jeff@garzik.org,
       akpm@linux-foundation.org, jens.axboe@oracle.com, rusty@rustcorp.com.au,
       cl@linux-foundation.org, dhowells@redhat.com, arjan@linux.intel.com,
       avi@redhat.com, johannes@sipsolutions.net, andi@firstfloor.org,
       Mike Galbraith <efault@gmx.de>
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Date: Wed, 20 Jan 2010 09:59:00 +0100
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On Wed, 2010-01-20 at 18:00 +0900, Tejun Heo wrote:
> Hello,
> 
> On 01/20/2010 05:50 PM, Peter Zijlstra wrote:
> > OK, so maybe I'm confused, but in general the workqueue thing needs to
> > ensure work affinity, right? So why can we move the rescue thread while
> > its processing another CPU's works?
> 
> It doesn't get moved directly.  The CPU requests rescuer and rescuer
> will move itself to the CPU when it becomes idle.  We can of course
> make the rescuer wake up some other thread and then go to sleep and
> the other thread can kthread_bind() the rescuer to the dying CPU but
> that exactly is what the set_cpus_allowed_ptr() does.

Ah, ok I thought it was all mitigated through the management thread.

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