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From: Oleg Nesterov <oleg@tv-sign.ru>
To: vatsa@in.ibm.com
Cc: linux-kernel@vger.kernel.org,
	Dipankar Sarma <dipankar@in.ibm.com>,
	Manfred Spraul <manfred@colorfullife.com>,
	Linus Torvalds <torvalds@osdl.org>,
	"Paul E. McKenney" <paulmck@us.ibm.com>,
	Andrew Morton <akpm@osdl.org>
Subject: Re: [PATCH 2/5] rcu: don't check ->donelist in __rcu_pending()
Date: Mon, 09 Jan 2006 18:33:03 +0300	[thread overview]
Message-ID: <43C2822F.F26F855E@tv-sign.ru> (raw)
In-Reply-To: 20060109134238.GA26700@in.ibm.com

Srivatsa Vaddagiri wrote:
> 
> On Mon, Jan 09, 2006 at 05:51:08PM +0300, Oleg Nesterov wrote:
> > Srivatsa Vaddagiri wrote:
> > >             If we have to do a rcu_move_batch of ->donelist also,
> > > then perhaps the ->donelist != NULL check is required in
> > > rcu_pending?
> >
> > rcu_move_batch() always adds entries to the ->nxttail, so I think
> > this patch is correct.
> 
> Hmm ..adding entries on dead cpu's ->donelist to ->nxtlist of some other CPU
> doesnt make sense (it re-triggers graceperiods for all those callbacks which is
> not needed).

Yes, but this is rare event, so ...

>              Maybe rcu_move_batch should take that into account and instead add
> to ->donelist of current CPU which is processing the CPU_DEAD callback.

May be you are right,

> In which case, ->donelist != NULL check is still reqd in rcu_pending ?

Yes, in that case it is required. Do you think it is worth to optimize
CPU_DEAD case?

Oleg.

  reply	other threads:[~2006-01-09 14:16 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-01-08 19:19 [PATCH 2/5] rcu: don't check ->donelist in __rcu_pending() Oleg Nesterov
2006-01-08 22:00 ` Paul E. McKenney
2006-01-09  9:31 ` Srivatsa Vaddagiri
2006-01-09 14:51   ` Oleg Nesterov
2006-01-09 13:42     ` Srivatsa Vaddagiri
2006-01-09 15:33       ` Oleg Nesterov [this message]
2006-01-09 18:59 ` Paul E. McKenney
2006-01-09 20:31   ` Oleg Nesterov
2006-01-09 19:59     ` Paul E. McKenney
2006-01-10  9:58       ` Srivatsa Vaddagiri
2006-01-10 14:24         ` [PATCH] rcu: fix hotplug-cpu ->donelist leak Oleg Nesterov
2006-01-11  5:01           ` Paul E. McKenney
2006-01-11 16:28           ` Paul E. McKenney
2006-01-11 19:25             ` Oleg Nesterov
2006-01-11 18:21               ` Paul E. McKenney
2006-01-10 14:27         ` [PATCH 2/5] rcu: don't check ->donelist in __rcu_pending() Oleg Nesterov
2006-01-10 18:13 ` Dipankar Sarma

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