Re: [PATCH RFC idle 1/3] x86: Avoid invoking RCU when CPU is idle

From: Frederic Weisbecker
Date: Wed Feb 01 2012 - 20:54:37 EST

On Wed, Feb 01, 2012 at 04:43:22PM -0800, Paul E. McKenney wrote:
> From: "Paul E. McKenney" <paul.mckenney@xxxxxxxxxx>
> The idle loop is a quiscent state for RCU, which means that RCU ignores
> CPUs that have told RCU that they are idle via rcu_idle_enter(). There
> are nevertheless quite a few places where idle CPUs use RCU, most commonly
> indirectly via tracing. This patch fixes these problems for x86.
> Many of these bugs have been in the kernel for quite some time, but
> Frederic's recent change now gives warnings.
> This patch takes the straightforward approach of pushing the
> rcu_idle_enter()/rcu_idle_exit() pair further down into the core
> of the idle loop.

I guess this is about the trace_power_*() things, right?

Acked-by: Frederic Weisbecker <fweisbec@xxxxxxxxx>

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