Date: Tue, 5 Jan 2010 15:09:32 +0900
From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
To: Minchan Kim <minchan.kim@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
       Peter Zijlstra <a.p.zijlstra@chello.nl>,
       "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
       Peter Zijlstra <peterz@infradead.org>,
       "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
       "linux-mm@kvack.org" <linux-mm@kvack.org>, cl@linux-foundation.org,
       "hugh.dickins" <hugh.dickins@tiscali.co.uk>,
       Nick Piggin <nickpiggin@yahoo.com.au>, Ingo Molnar <mingo@elte.hu>
Subject: Re: [RFC][PATCH 6/8] mm: handle_speculative_fault()
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On Tue, 5 Jan 2010 15:09:47 +0900
Minchan Kim <minchan.kim@gmail.com> wrote:
> My humble opinion is following as.
> 
> Couldn't we synchronize rcu in that cases(munmap, exit and so on)?
> It can delay munap and exit but it would be better than handling them by more
> complicated things, I think. And both cases aren't often cases so we
> can achieve advantage than disadvantage?
> 

In most case, a program is single threaded. And sychronize_rcu() in unmap path
just adds very big overhead.

Thanks,
-Kame

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