Re: [PATCH RFC idle 1/3] x86: Avoid invoking RCU when CPU is idle
From: Paul E. McKenney
Date: Wed Feb 01 2012 - 23:55:59 EST
On Thu, Feb 02, 2012 at 02:54:30AM +0100, Frederic Weisbecker wrote:
> 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?
Indeed it is! Alternative suggestions gladly accepted. ;-)
> Acked-by: Frederic Weisbecker <fweisbec@xxxxxxxxx>
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/