Re: [RFC 1/2] rcu: Do prepare and cleanup idle depending on in_nmi()

[Steven Rostedt]

On Wed, 20 Jun 2018 08:56:58 -0700
"Paul E. McKenney" <paulmck@xxxxxxxxxxxxxxxxxx> 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