From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Steven Rostedt <rostedt@goodmis.org>
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, dvhltc@us.ibm.com, niv@us.ibm.com,
tglx@linutronix.de, peterz@infradead.org,
Valdis.Kletnieks@vt.edu, dhowells@redhat.com
Subject: Re: [PATCH tip/core/rcu 2/3] rcu: make hot-unplugged CPU relinquish its own RCU callbacks
Date: Wed, 7 Oct 2009 06:50:49 -0700 [thread overview]
Message-ID: <20091007135049.GF6838@linux.vnet.ibm.com> (raw)
In-Reply-To: <1254921372.1696.132.camel@gandalf.stny.rr.com>
On Wed, Oct 07, 2009 at 09:16:12AM -0400, Steven Rostedt wrote:
> Paul,
>
> Still suffering jetlag? ;-)
As a matter of fact, yes. ;-)
> On Tue, 2009-10-06 at 21:48 -0700, Paul E. McKenney wrote:
> > From: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
> >
> > The current interaction between RCU and CPU hotplug requires that
> > RCU block in CPU notifiers waiting for callbacks to drain. This can
> > be greatly simplified by haing each CPU relinquish its own callbacks,
> having
>
> > and for both _rcu_barrier() and CPU_DEAD notifiers to adopt all callbacks
> > that were previously relinquished. This change also eliminates the
> > possibility of certain types of hangs due to the previous practice of
> > waiting for callbacks to be invoked from within CPU notifiers. If you
> > don't every wait, you cannot hang.
> ever
>
> ;-)
Courtesy of "git cherry-pick" and my being out of it. ;-)
Thanx, Paul
> > Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
>
> -- Steve
>
>
next prev parent reply other threads:[~2009-10-07 13:51 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-10-07 4:47 [PATCH tip/core/rcu 0/3] rcu: prevent hangs by simplifying rcu_barrier/CPU-hotplug, fix lockdep complaint Paul E. McKenney
2009-10-07 4:48 ` [PATCH tip/core/rcu 1/3] rcu: move rcu_barrier() to rcutree Paul E. McKenney
2009-10-07 6:16 ` [tip:core/rcu] rcu: Move " tip-bot for Paul E. McKenney
2009-10-07 4:48 ` [PATCH tip/core/rcu 2/3] rcu: make hot-unplugged CPU relinquish its own RCU callbacks Paul E. McKenney
2009-10-07 6:17 ` [tip:core/rcu] rcu: Make " tip-bot for Paul E. McKenney
2009-10-07 13:16 ` [PATCH tip/core/rcu 2/3] rcu: make " Steven Rostedt
2009-10-07 13:50 ` Paul E. McKenney [this message]
2009-10-07 4:48 ` [PATCH tip/core/rcu 3/3] rcu: place root rcu_node structure in separate lockdep class Paul E. McKenney
2009-10-07 6:17 ` [tip:core/rcu] rcu: Place " tip-bot for Paul E. McKenney
2009-10-08 9:31 ` [PATCH tip/core/rcu 3/3] rcu: place " Peter Zijlstra
2009-10-07 6:14 ` [PATCH tip/core/rcu 0/3] rcu: prevent hangs by simplifying rcu_barrier/CPU-hotplug, fix lockdep complaint Ingo Molnar
2009-10-07 13:52 ` Paul E. McKenney
2009-10-07 12:55 [PATCH tip/core/rcu 2/3] rcu: make hot-unplugged CPU relinquish its own RCU callbacks Mathieu Desnoyers
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