From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Christoph Lameter <cl@linux-foundation.org>
Cc: Evgeniy Polyakov <johnpol@2ka.mipt.ru>,
Corey Minyard <minyard@acm.org>,
David Miller <davem@davemloft.net>,
dada1@cosmosbay.com, linux-kernel@vger.kernel.org,
netdev@vger.kernel.org, shemminger@vyatta.com
Subject: Re: [PATCH 3/3] Convert the UDP hash lock to RCU
Date: Tue, 7 Oct 2008 07:33:46 -0700 [thread overview]
Message-ID: <20081007143346.GA6384@linux.vnet.ibm.com> (raw)
In-Reply-To: <48EB6F2D.100@linux-foundation.org>
On Tue, Oct 07, 2008 at 09:16:13AM -0500, Christoph Lameter wrote:
> Evgeniy Polyakov wrote:
> > On Mon, Oct 06, 2008 at 06:08:09PM -0500, Corey Minyard (minyard@acm.org) wrote:
> >> Would using SLAB_DESTROY_BY_RCU be ok, or would that be too expensive?
> >
> > I tested skb destruction via RCU path, and got 2.5 times worse numbers
> > with small-packets-bulk-transfer workload.
>
> Was this with regular RCU freeing? This will cool down the cacheline before
> frees. You need SLAB_DESTROY_BY_RCU to keep the objects cache hot.
Indeed!
But care is required -- SLAB_DESTROY_BY_RCU permits objects to be freed
and reallocated while a reader holds a reference. The only guarantee is
that the -type- of the data structure will not change while a reader holds
a reference. With something like UDP, this might well be sufficient.
Just be careful! ;-)
Thanx, Paul
next prev parent reply other threads:[~2008-10-07 14:40 UTC|newest]
Thread overview: 134+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-10-06 18:50 [PATCH 3/3] Convert the UDP hash lock to RCU 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 [this message]
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
2008-10-28 20:37 ` [PATCH 1/2] udp: introduce struct udp_table and multiple rwlocks Eric Dumazet
2008-10-28 21:23 ` Christian Bell
2008-10-28 21:31 ` Evgeniy Polyakov
2008-10-28 21:48 ` Eric Dumazet
2008-10-28 21:28 ` Evgeniy Polyakov
2008-10-28 20:42 ` [PATCH 2/2] udp: RCU handling for Unicast packets Eric Dumazet
2008-10-28 22:45 ` Eric Dumazet
2008-10-29 5:05 ` David Miller
2008-10-29 8:23 ` Eric Dumazet
2008-10-29 8:56 ` David Miller
2008-10-29 10:19 ` Eric Dumazet
2008-10-29 18:19 ` David Miller
2008-10-29 9:04 ` Eric Dumazet
2008-10-29 9:17 ` David Miller
2008-10-29 13:17 ` Corey Minyard
2008-10-29 14:36 ` Eric Dumazet
2008-10-29 15:34 ` Corey Minyard
2008-10-29 16:09 ` Eric Dumazet
2008-10-29 16:37 ` Paul E. McKenney
2008-10-29 17:22 ` Corey Minyard
2008-10-29 17:45 ` Eric Dumazet
2008-10-29 18:28 ` Corey Minyard
2008-10-29 18:52 ` Paul E. McKenney
2008-10-29 20:00 ` Eric Dumazet
2008-10-29 20:17 ` Paul E. McKenney
2008-10-29 21:29 ` Corey Minyard
2008-10-29 21:57 ` Eric Dumazet
2008-10-29 21:58 ` Paul E. McKenney
2008-10-29 22:08 ` Eric Dumazet
2008-10-30 3:22 ` Corey Minyard
2008-10-30 5:50 ` Eric Dumazet
2008-11-02 4:19 ` David Miller
2008-10-30 5:40 ` David Miller
2008-10-30 5:51 ` Eric Dumazet
2008-10-30 7:04 ` Eric Dumazet
2008-10-30 7:05 ` David Miller
2008-10-30 15:40 ` [PATCH] udp: Introduce special NULL pointers for hlist termination Eric Dumazet
2008-10-30 15:51 ` Stephen Hemminger
2008-10-30 16:28 ` Corey Minyard
2008-10-31 14:37 ` Eric Dumazet
2008-10-31 14:55 ` Pavel Emelyanov
2008-11-02 4:22 ` David Miller
2008-10-30 17:12 ` Eric Dumazet
2008-10-31 7:51 ` David Miller
2008-10-30 16:01 ` Peter Zijlstra
2008-10-31 0:14 ` Keith Owens
2008-11-13 13:13 ` [PATCH 0/3] net: RCU lookups for UDP, DCCP and TCP protocol Eric Dumazet
2008-11-13 17:20 ` Andi Kleen
2008-11-17 3:41 ` David Miller
2008-11-19 19:52 ` Christoph Lameter
2008-11-13 13:14 ` [PATCH 1/3] rcu: Introduce hlist_nulls variant of hlist Eric Dumazet
2008-11-13 13:29 ` Peter Zijlstra
2008-11-13 13:44 ` Eric Dumazet
2008-11-13 16:02 ` [PATCH 4/3] rcu: documents rculist_nulls Eric Dumazet
2008-11-14 15:16 ` Peter Zijlstra
2008-11-17 3:36 ` David Miller
2008-11-19 17:07 ` Paul E. McKenney
2008-11-14 15:16 ` [PATCH 1/3] rcu: Introduce hlist_nulls variant of hlist Peter Zijlstra
2008-11-19 17:01 ` Paul E. McKenney
2008-11-19 17:53 ` Eric Dumazet
2008-11-19 18:46 ` Paul E. McKenney
2008-11-19 18:53 ` Arnaldo Carvalho de Melo
2008-11-19 21:17 ` Paul E. McKenney
2008-11-19 20:39 ` Eric Dumazet
2008-11-19 21:21 ` Paul E. McKenney
2008-11-13 13:15 ` [PATCH 2/3] udp: Use hlist_nulls in UDP RCU code Eric Dumazet
2008-11-19 17:29 ` Paul E. McKenney
2008-11-19 17:53 ` Eric Dumazet
2008-11-13 13:15 ` [PATCH 3/3] net: Convert TCP & DCCP hash tables to use RCU / hlist_nulls Eric Dumazet
2008-11-13 13:34 ` Peter Zijlstra
2008-11-13 13:51 ` Eric Dumazet
2008-11-13 14:08 ` Christoph Lameter
2008-11-13 14:22 ` Peter Zijlstra
2008-11-13 14:27 ` Christoph Lameter
2008-11-19 17:53 ` Paul E. McKenney
2008-11-23 9:33 ` [PATCH] net: Convert TCP/DCCP listening hash tables to use RCU Eric Dumazet
2008-11-23 15:59 ` Paul E. McKenney
2008-11-23 18:42 ` Eric Dumazet
2008-11-23 19:17 ` Paul E. McKenney
2008-11-23 20:18 ` Eric Dumazet
2008-11-23 22:33 ` Paul E. McKenney
2008-11-24 1:23 ` David Miller
2008-10-30 11:04 ` [PATCH 2/2] udp: RCU handling for Unicast packets Peter Zijlstra
2008-10-30 11:30 ` Eric Dumazet
2008-10-30 18:25 ` Paul E. McKenney
2008-10-31 16:40 ` Eric Dumazet
2008-11-01 3:10 ` Paul E. McKenney
2008-10-29 17:32 ` Eric Dumazet
2008-10-29 18:11 ` Paul E. McKenney
2008-10-29 18:29 ` David Miller
2008-10-29 18:38 ` Paul E. McKenney
2008-10-29 18:36 ` Eric Dumazet
2008-10-29 18:20 ` David Miller
2008-10-30 11:12 ` Peter Zijlstra
2008-10-30 11:29 ` Eric Dumazet
2008-10-28 20:37 ` [PATCH 0/2] udp: Convert the UDP hash lock to RCU Eric Dumazet
2008-10-28 21:28 ` Stephen Hemminger
2008-10-28 21:50 ` Eric Dumazet
2008-10-07 16:43 ` [PATCH 3/3] " 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
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