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Date: Fri, 1 Aug 2008 14:10:32 -0700
From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Ingo Molnar <mingo@elte.hu>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>, Dipankar Sarma <dipankar@in.ibm.com>,
       Gautham Shenoy <ego@in.ibm.com>,
       Dhaval Giani <dhaval@linux.vnet.ibm.com>,
       Peter Zijlstra <a.p.zijlstra@chello.nl>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [RFC][PATCH 2/2] rcu classic: new algorithm for
	callbacks-processing(v2)
Message-ID: <20080801211032.GT14851@linux.vnet.ibm.com>
Reply-To: paulmck@linux.vnet.ibm.com
References: <48708F2F.2060406@cn.fujitsu.com> <20080718140930.GT6875@elte.hu>
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On Fri, Jul 18, 2008 at 04:09:30PM +0200, Ingo Molnar wrote:
> 
> * Lai Jiangshan <laijs@cn.fujitsu.com> wrote:
> 
> > This is v2, it's a little deference from v1 that I
> > had send to lkml.
> > use ACCESS_ONCE
> > use rcu_batch_after/rcu_batch_before for batch # comparison.
> > 
> > rcutorture test result:
> > (hotplugs: do cpu-online/offline once per second)
> > 
> > No CONFIG_NO_HZ:           OK, 12hours
> > No CONFIG_NO_HZ, hotplugs: OK, 12hours
> > CONFIG_NO_HZ=y:            OK, 24hours
> > CONFIG_NO_HZ=y, hotplugs:  Failed.
> > (Failed also without my patch applied, exactly the same bug occurred,
> > http://lkml.org/lkml/2008/7/3/24)
> 
> thanks, i've applied this to tip/core/rcu - but it would be nice have an 
> ack/nak from Paul as well, before we can proceed further.

I like the general approach -- simplification is a good thing.

So, for the moment:

Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

I need to do a more detailed review (e.g., the memory-barrier changes
and the incorporation of some grace-period processing into call_rcu()),
after which I will either ask for changes or give a Reviewed-by.

I need to do this more-detailed review before we ship to mainline.
(Gak, already two weeks since Jiangshan sent this!!!  My apologies!!!)

							Thanx, Paul