From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Frederic Weisbecker <fweisbec@gmail.com>
Cc: linux-kernel@vger.kernel.org, mingo@elte.hu,
laijs@cn.fujitsu.com, dipankar@in.ibm.com,
akpm@linux-foundation.org, mathieu.desnoyers@polymtl.ca,
josh@joshtriplett.org, niv@us.ibm.com, tglx@linutronix.de,
peterz@infradead.org, rostedt@goodmis.org,
Valdis.Kletnieks@vt.edu, dhowells@redhat.com,
eric.dumazet@gmail.com, darren@dvhart.com, patches@linaro.org,
"Paul E. McKenney" <paul.mckenney@linaro.org>,
"H. Peter Anvin" <hpa@zytor.com>, Len Brown <lenb@kernel.org>,
Borislav Petkov <bp@alien8.de>,
Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>,
Stephen Wilson <wilsons@start.ca>,
linux-pm@vger.kernel.org, x86@kernel.org
Subject: Re: [PATCH RFC idle 1/3] x86: Avoid invoking RCU when CPU is idle
Date: Wed, 1 Feb 2012 20:55:38 -0800 [thread overview]
Message-ID: <20120202045538.GF2435@linux.vnet.ibm.com> (raw)
In-Reply-To: <20120202015428.GA8807@somewhere.redhat.com>
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@linaro.org>
> >
> > 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. ;-)
Thanx, Paul
> Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
>
> Thanks.
>
next prev parent reply other threads:[~2012-02-02 4:55 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-02 0:42 [PATCH RFC idle] Make arm, sh, and x86 stop using RCU when idle Paul E. McKenney
2012-02-02 0:43 ` [PATCH RFC idle 1/3] x86: Avoid invoking RCU when CPU is idle Paul E. McKenney
2012-02-02 0:43 ` [PATCH RFC idle 3/3] sh: " Paul E. McKenney
2012-02-02 1:54 ` [PATCH RFC idle 1/3] x86: " Frederic Weisbecker
2012-02-02 4:55 ` Paul E. McKenney [this message]
2012-02-02 0:48 ` [PATCH RFC idle] Make arm, sh, and x86 stop using RCU when idle Josh Triplett
2012-02-02 1:14 ` Paul E. McKenney
2012-02-02 2:29 ` Paul Mundt
2012-02-02 4:58 ` Paul E. McKenney
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