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Date: Fri, 27 Jul 2012 18:58:29 +0200
From: Frederic Weisbecker <fweisbec@gmail.com>
To: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
        Alessio Igor Bogani <abogani@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>, Avi Kivity <avi@redhat.com>,
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        Geoff Levand <geoff@infradead.org>,
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        Hakan Akkan <hakanakkan@gmail.com>, "H. Peter Anvin" <hpa@zytor.com>,
        Ingo Molnar <mingo@kernel.org>, Kevin Hilman <khilman@ti.com>,
        Max Krasnyansky <maxk@qualcomm.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Stephen Hemminger <shemminger@vyatta.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Sven-Thorsten Dietrich <thebigcorporation@gmail.com>,
        Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH 1/5] user_hooks: New user hooks subsystem
Message-ID: <20120727165824.GN1173@somewhere.redhat.com>
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On Fri, Jul 27, 2012 at 09:40:54AM -0700, Paul E. McKenney wrote:
> On Fri, Jul 27, 2012 at 05:40:30PM +0200, Frederic Weisbecker wrote:
> > Create a new subsystem that handles the hooks on kernel/user
> > boundaries currently used by RCU for its userspace extended
> > quiescent state.
> > 
> > We need to pull this up from RCU into this new level of indirection
> > because these hooks are also going to be used to implement an "on
> > demand" generic virtual cputime accounting. A necessary step to
> > shutdown the tick while still accounting the cputime.
> 
> So this eliminates the case where the architecture might enter an
> RCU extended quiescent state multiple times, but exit it only once?
> (I am hoping that it does...)

Yeah. It should handle that.