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Date: Mon, 23 Sep 2013 18:02:54 +0200
From: Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH] hotplug: Optimize {get,put}_online_cpus()
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To: Steven Rostedt <rostedt@goodmis.org>
Cc: Mel Gorman <mgorman@suse.de>, Rik van Riel <riel@redhat.com>, Srikar Dronamraju <srikar@linux.vnet.ibm.com>, Ingo Molnar <mingo@kernel.org>, Andrea Arcangeli <aarcange@redhat.com>, Johannes Weiner <hannes@cmpxchg.org>, Linux-MM <linux-mm@kvack.org>, LKML <linux-kernel@vger.kernel.org>, Oleg Nesterov <oleg@redhat.com>, Paul McKenney <paulmck@linux.vnet.ibm.com>, Thomas Gleixner <tglx@linutronix.de>

On Mon, Sep 23, 2013 at 11:59:08AM -0400, Steven Rostedt wrote:
> On Mon, 23 Sep 2013 17:22:23 +0200
> Peter Zijlstra <peterz@infradead.org> wrote:
> 
> > Still no point in using srcu for this; preempt_disable +
> > synchronize_sched() is similar and much faster -- its the rcu_sched
> > equivalent of what you propose.
> 
> To be honest, I sent this out last week and it somehow got trashed by
> my laptop and connecting to my smtp server. Where the last version of
> your patch still had the memory barrier ;-)

Ah, ok, yes in that case things start to make sense again.

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