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Date:   Wed, 20 Jun 2018 12:11:56 -0400
From:   Steven Rostedt <rostedt@goodmis.org>
To:     "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc:     Byungchul Park <byungchul.park@lge.com>, jiangshanlai@gmail.com,
        josh@joshtriplett.org, mathieu.desnoyers@efficios.com,
        linux-kernel@vger.kernel.org, kernel-team@lge.com,
        joel@joelfernandes.org
Subject: Re: [RFC 1/2] rcu: Do prepare and cleanup idle depending on
 in_nmi()
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On Wed, 20 Jun 2018 08:56:58 -0700
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com> wrote:

> OK, so in theory this change is safe from a tracing perspective.  But
> it does add conditionals to a fastpath.

Does it?

I see it replacing two conditions from both rcu_irq_enter/exit() with a
single one in rcu_nmi_enter/exit(). Sure it adds one to rcu_nmi_enter()
but that's a far less fast path than rcu_irq_enter(), which this patch
removes a conditional from.

-- Steve