Date: Fri, 24 Aug 2007 13:51:21 +0530
From: Gautham R Shenoy <ego@in.ibm.com>
To: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: linux-kernel@vger.kernel.org, linux-rt-users@vger.kernel.org,
       mingo@elte.hu, akpm@linux-foundation.org, dipankar@in.ibm.com,
       josht@linux.vnet.ibm.com, tytso@us.ibm.com, dvhltc@us.ibm.com,
       tglx@linutronix.de
Subject: Re: [PATCH RFC] Priority boosting for preemptible RCU
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On Thu, Aug 23, 2007 at 08:55:26AM -0700, Paul E. McKenney wrote:
> > Even if we use another cpumask_t, whenever a cpu goes down or comes up,
> > that will be reflected in this map, no? So what's the additional
> > advantage of using it?
> 
> The additional map allows the code to use something other than the
> lock_cpu_hotplug/unlock_cpu_hotplug, and also is robust against any
> changes to the hotplug synchronization mechanism.  Might well be
> better just to use the current hotplug synchronization mechanism,
> but I was feeling paranoid.  ;-)

If it was doing something more complicated in the critical section other
than summing stuff up, I would probably recommend going for another map
instead of using the current hotplug synchronization. But for this case
the current hotplug synchronization would work just fine.

I can very well understand your paranoia, but let me assure you, you are
not the only one ;-)

Regards
gautham.
> 
> 						Thanx, Paul

-- 
Gautham R Shenoy
Linux Technology Center
IBM India.
"Freedom comes with a price tag of responsibility, which is still a bargain,
because Freedom is priceless!"
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