From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: David Miller <davem@davemloft.net>,
dada1@cosmosbay.com, minyard@acm.org,
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 07:36:11 -0700 [thread overview]
Message-ID: <20081007143611.GB6384@linux.vnet.ibm.com> (raw)
In-Reply-To: <1223368290.26330.10.camel@lappy.programming.kicks-ass.net>
On Tue, Oct 07, 2008 at 10:31:30AM +0200, Peter Zijlstra wrote:
> On Mon, 2008-10-06 at 14:40 -0700, David Miller wrote:
> > From: Eric Dumazet <dada1@cosmosbay.com>
> > Date: Mon, 06 Oct 2008 23:22:31 +0200
> >
> > > Me wondering what impact this synchronize_rcu() can have on mono-threaded
> > > VOIP applications using lot of UDP sockets. What is the maximum delay of
> > > this function ?
> >
> > The cost is enormous, we really can't use it here.
> >
> > I have a patch that did top-level socket destruction using RCU,
> > and that didn't use synchronize_rcu(), and that killed connection
> > rates by up to %20.
>
> Did you ever figure out why you lost those 20% ?
>
> > I can only imagine what the cost would be if I had to add such a call
> > in there.
>
> Yeah, sync_rcu() is rediculously expensive, at best 3 jiffies IIRC.
I could make it -much- faster, but at the expense of -serious- CPU
overhead. Still, might be useful during boot time (when the system
can't do anything useful anyway) to accelerate getting data structures
initialized.
Thanx, Paul
next prev parent reply other threads:[~2008-10-07 14:36 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
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 [this message]
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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