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Message-ID: <1338496676.13348.430.camel@gandalf.stny.rr.com>
Subject: Re: [PATCH 1/5] ftrace: Synchronize variable setting with
 breakpoints
From: Steven Rostedt <rostedt@goodmis.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        linux-kernel@vger.kernel.org, Ingo Molnar <mingo@elte.hu>,
        Andrew Morton <akpm@linux-foundation.org>,
        Frederic Weisbecker <fweisbec@gmail.com>,
        Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>,
        "H. Peter Anvin" <hpa@zytor.com>, Dave Jones <davej@redhat.com>,
        Andi Kleen <ak@linux.intel.com>, acme <acme@ghostprotocols.net>
Date: Thu, 31 May 2012 16:37:56 -0400
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On Thu, 2012-05-31 at 22:26 +0200, Peter Zijlstra wrote:

> Right, but when you loose stop-machine you could simply do 30k
> kmap_atomic/kunmap_atomic's consecutively since you're not holding
> anybody up.

It requires 3 IPIs per update too. Thus that's 90,000 IPIs you are
blasting^Wsending to all CPUs.

-- Steve


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