From: Christoph Lameter <cl@linux-foundation.org>
To: Eric Dumazet <dada1@cosmosbay.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>,
minyard@acm.org, Linux Kernel <linux-kernel@vger.kernel.org>,
netdev@vger.kernel.org, shemminger@vyatta.com,
paulmck@linux.vnet.ibm.com
Subject: Re: [PATCH 3/3] Convert the UDP hash lock to RCU
Date: Tue, 07 Oct 2008 10:23:22 -0500 [thread overview]
Message-ID: <48EB7EEA.4040809@linux-foundation.org> (raw)
In-Reply-To: <48EB7747.9060505@cosmosbay.com>
Eric Dumazet wrote:
>
> 1) Hum, do you know why "struct file" objects dont use
> SLAB_DESTROY_BY_RCU then,
> since we noticed a performance regression for several workloads at
> RCUification
> of file structures ?
Because my patches were not accepted that fix the issue.
http://lkml.org/lkml/2006/6/16/144
> 2) What prevents an object to be *freed* (and deleted from a hash
> chain), then
> re-allocated and inserted to another chain (different keys) ? (final
> refcount=1)
Nothing.
> If the lookup detects a key mismatch, how will it continue to the next
> item,
> since 'next' pointer will have been reused for the new chain insertion...
>
> Me confused...
If there is a mismatch then you have to do another hash lookup. Do an rcu
unlock and start over.
prev parent reply other threads:[~2008-10-07 15:24 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-10-06 18:50 Corey Minyard
2008-10-06 21:22 ` Eric Dumazet
2008-10-06 21:40 ` David Miller
2008-10-06 23:08 ` Corey Minyard
2008-10-07 8:37 ` Evgeniy Polyakov
2008-10-07 14:16 ` Christoph Lameter
2008-10-07 14:29 ` Evgeniy Polyakov
2008-10-07 14:38 ` Christoph Lameter
2008-10-07 14:33 ` Paul E. McKenney
2008-10-07 14:45 ` Christoph Lameter
2008-10-07 15:07 ` Eric Dumazet
2008-10-07 15:07 ` Paul E. McKenney
2008-10-07 5:24 ` Eric Dumazet
2008-10-07 8:54 ` Benny Amorsen
2008-10-07 12:59 ` Eric Dumazet
2008-10-07 14:07 ` Stephen Hemminger
2008-10-07 20:55 ` David Miller
2008-10-07 21:20 ` Stephen Hemminger
2008-10-08 13:55 ` Eric Dumazet
2008-10-08 18:45 ` David Miller
2008-10-07 16:43 ` Corey Minyard
2008-10-07 18:26 ` David Miller
2008-10-08 8:35 ` Eric Dumazet
2008-10-08 16:38 ` David Miller
2008-10-07 8:31 ` Peter Zijlstra
2008-10-07 14:36 ` Paul E. McKenney
2008-10-07 18:29 ` David Miller
2008-10-06 22:07 ` Corey Minyard
2008-10-07 8:17 ` Peter Zijlstra
2008-10-07 9:24 ` Eric Dumazet
2008-10-07 14:15 ` Christoph Lameter
2008-10-07 14:38 ` Paul E. McKenney
2008-10-07 14:50 ` Eric Dumazet
2008-10-07 15:05 ` Paul E. McKenney
2008-10-07 15:09 ` Peter Zijlstra
2008-10-07 15:23 ` Christoph Lameter [this message]
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