Subject: Re: [PATCH -mmotm 1/5] memcg: disable irq at page cgroup lock
From: Peter Zijlstra <peterz@infradead.org>
To: Greg Thelen <gthelen@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
       Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>,
       Vivek Goyal <vgoyal@redhat.com>, balbir@linux.vnet.ibm.com,
       Andrea Righi <arighi@develer.com>,
       Trond Myklebust <trond.myklebust@fys.uio.no>,
       Suleiman Souhlal <suleiman@google.com>,
       "Kirill A. Shutemov" <kirill@shutemov.name>,
       Andrew Morton <akpm@linux-foundation.org>,
       containers@lists.linux-foundation.org, linux-kernel@vger.kernel.org,
       linux-mm@kvack.org
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Date: Fri, 23 Apr 2010 22:57:06 +0200
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On Fri, 2010-04-23 at 13:17 -0700, Greg Thelen wrote:
> +static void mem_cgroup_begin_page_cgroup_reassignment(void)
> +{
> +       VM_BUG_ON(mem_cgroup_account_move_ongoing);
> +       mem_cgroup_account_move_ongoing = true;
> +       synchronize_rcu();
> +} 

btw, you know synchronize_rcu() is _really_ slow?

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