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From: Peter Zijlstra <peterz@infradead.org>
To: frank.rowand@am.sony.com
Cc: Chris Mason <chris.mason@oracle.com>, Ingo Molnar <mingo@elte.hu>,
	"axboe@kernel.dk" <axboe@kernel.dk>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Mike Galbraith <efault@gmx.de>, Oleg Nesterov <oleg@redhat.com>,
	tglx <tglx@linutronix.de>
Subject: Re: [PATCH RFC] reduce runqueue lock contention
Date: Thu, 02 Dec 2010 08:36:49 +0100	[thread overview]
Message-ID: <1291275409.4023.21.camel@twins> (raw)
In-Reply-To: <4CF6D694.4030003@am.sony.com>

On Wed, 2010-12-01 at 15:13 -0800, Frank Rowand wrote:
> 
>   If the task to be woken is on a run queue on a different cpu then use
>   cmpxchg() to put it onto a pending try_to_wake_up list on the different
>   cpu.  Then send an interrupt to the different cpu to cause that cpu to
>   call try_to_wake_up() for each process on the try_to_wake_up list. 

Without having looked at the actual code, the described thing cannot
work, try_to_wake_up() has a return value that needs to be passed back.

Also, try_to_wake_up() does load-balancing, you really want to do that
before queueing it on a remote cpu.

  parent reply	other threads:[~2010-12-02  7:37 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-05-20 20:48 [PATCH RFC] reduce runqueue lock contention Chris Mason
2010-05-20 21:09 ` Peter Zijlstra
2010-05-20 21:23   ` Peter Zijlstra
2010-05-20 22:17     ` Chris Mason
2010-05-20 22:21   ` Chris Mason
2010-06-04 10:56 ` Stijn Devriendt
2010-06-04 12:00   ` Peter Zijlstra
2010-06-05  9:37     ` Stijn Devriendt
2010-06-21 10:02 ` Peter Zijlstra
2010-06-21 10:54   ` Peter Zijlstra
2010-06-21 13:04     ` Peter Zijlstra
2010-06-22 13:33       ` Peter Zijlstra
2010-06-22 21:11         ` Ingo Molnar
2010-06-23  9:10           ` Peter Zijlstra
2010-12-01 23:13             ` Frank Rowand
2010-12-02  1:17               ` Frank Rowand
2010-12-02  7:36               ` Peter Zijlstra [this message]
2010-12-14  2:41       ` Frank Rowand
2010-12-14  3:42         ` Mike Galbraith
2010-12-14 21:42           ` Frank Rowand
2010-12-15 18:59         ` Oleg Nesterov

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