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Date: Thu, 26 Feb 2009 20:17:56 +0900 (JST)
Subject: Re: [PATCH] cpuacct: add a branch prediction
From: "KAMEZAWA Hiroyuki" <kamezawa.hiroyu@jp.fujitsu.com>
To: "Peter Zijlstra" <a.p.zijlstra@chello.nl>
Cc: "KAMEZAWA Hiroyuki" <kamezawa.hiroyu@jp.fujitsu.com>,
       "Bharata B Rao" <bharata.rao@gmail.com>,
       "Li Zefan" <lizf@cn.fujitsu.com>, "Ingo Molnar" <mingo@elte.hu>,
       "Paul Menage" <menage@google.com>,
       "Balbir Singh" <balbir@linux.vnet.ibm.com>,
       "LKML" <linux-kernel@vger.kernel.org>
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Peter Zijlstra さんは書きました：
> On Thu, 2009-02-26 at 19:28 +0900, KAMEZAWA Hiroyuki wrote:
>
>> Taking hierarchy mutex while reading will make read-side stable.
>
> We're talking about scheduling here, taking a mutex to stop scheduling
> won't work, nor will it be acceptible to use anything that will.
>
No mutex is necessary, anyway.
hierarchy-walker function completely works well under rcu read lock,
if small jitter is allowed.

Thanks,
-Kame