Date: Wed, 10 Nov 2010 20:19:20 -0800
From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>,
        Lai Jiangshan <laijs@cn.fujitsu.com>, Joe Korty <joe.korty@ccur.com>,
        mathieu.desnoyers@efficios.com, dhowells@redhat.com,
        loic.minier@linaro.org, dhaval.giani@gmail.com, tglx@linutronix.de,
        linux-kernel@vger.kernel.org, josh@joshtriplett.org,
        houston.jim@comcast.net
Subject: Re: [PATCH] a local-timer-free version of RCU
Message-ID: <20101111041920.GD3134@linux.vnet.ibm.com>
Reply-To: paulmck@linux.vnet.ibm.com
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On Wed, Nov 10, 2010 at 06:31:11PM +0100, Peter Zijlstra wrote:
> On Wed, 2010-11-10 at 16:54 +0100, Frederic Weisbecker wrote:
> > run the sched tick and if there was nothing to do
> > for some time and we are in userspace, deactivate it. 
> 
> Not for some time, immediately, have the tick track if it was useful, if
> it was not, have it stop itself, like:
> 
> tick()
> {
>  int stop = 1;
> 
>  if (nr_running > 1)
>   stop = 0;
> 
>  if(rcu_needs_cpu())
>   stop = 0;
> 
>  ...
> 
> 
>  if (stop)
>   enter_nohz_mode();
> }

I am still holding out for a dyntick-hpc version of RCU that does not
need the tick.  ;-)

							Thanx, Paul
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