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Subject: Re: perf events ring buffer memory barrier on powerpc
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To: Oleg Nesterov <oleg@redhat.com>
Cc: Anton Blanchard <anton@samba.org>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Frederic Weisbecker <fweisbec@gmail.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Linux PPC dev <linuxppc-dev@ozlabs.org>,
        Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>,
        Michael Ellerman <michael@ellerman.id.au>,
        Michael Neuling <mikey@neuling.org>,
        "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
        Peter Zijlstra <peterz@infradead.org>
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From: Victor Kaplansky <VICTORK@il.ibm.com>
Date: Mon, 28 Oct 2013 22:58:58 +0200
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Oleg Nesterov <oleg@redhat.com> wrote on 10/28/2013 10:17:35 PM:

>       mb();   // XXXXXXXX: do we really need it? I think yes.

Oh, it is hard to argue with feelings. Also, it is easy to be on
conservative side and put the barrier here just in case.
But I still insist that the barrier is redundant in your example.

-- Victor

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