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Date: Mon, 21 Nov 2016 14:06:41 -0500
From: Steven Rostedt <rostedt@goodmis.org>
To: Andi Kleen <andi@firstfloor.org>
Cc: Peter Zijlstra <peterz@infradead.org>, Jiri Olsa <jolsa@redhat.com>,
        "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
        linux-kernel@vger.kernel.org, Ingo Molnar <mingo@kernel.org>,
        Josh Triplett <josh@joshtriplett.org>,
        Jan Stancek <jstancek@redhat.com>
Subject: Re: [BUG] msr-trace.h:42 suspicious rcu_dereference_check() usage!
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On Mon, 21 Nov 2016 10:37:00 -0800
Andi Kleen <andi@firstfloor.org> wrote:

> Ok so how should tracing in idle code work then in your opinion?

As I suggested already. If we can get a light weight rcu_is_watching()
then we can do the rcu_idle work when needed, and not when we don't
need it. Sure this will add more branches, but that's still cheaper
than popf.

-- Steve