From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: [PATCH v2 nf-next] netfilter: conntrack: remove the central spinlock Date: Wed, 22 May 2013 12:26:12 -0700 Message-ID: <1369250772.3301.349.camel@edumazet-glaptop> References: <1368068665.13473.81.camel@edumazet-glaptop> <1369244868.3301.343.camel@edumazet-glaptop> <1369246816.2143.84.camel@joe-AO722> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: Pablo Neira Ayuso , netfilter-devel@vger.kernel.org, netdev , Tom Herbert , Patrick McHardy To: Joe Perches Return-path: Received: from mail-pa0-f53.google.com ([209.85.220.53]:33703 "EHLO mail-pa0-f53.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755190Ab3EVT0O (ORCPT ); Wed, 22 May 2013 15:26:14 -0400 In-Reply-To: <1369246816.2143.84.camel@joe-AO722> Sender: netdev-owner@vger.kernel.org List-ID: On Wed, 2013-05-22 at 11:20 -0700, Joe Perches wrote: > On Wed, 2013-05-22 at 10:47 -0700, Eric Dumazet wrote: > > From: Eric Dumazet > > > > nf_conntrack_lock is a monolithic lock and suffers from huge contention > > on current generation servers (8 or more core/threads). > [] > > diff --git a/include/net/netfilter/nf_conntrack.h b/include/net/netfilter/nf_conntrack.h > [] > > @@ -76,7 +76,8 @@ struct nf_conn { > > plus 1 for any connection(s) we are `master' for */ > > struct nf_conntrack ct_general; > > > > - spinlock_t lock; > > + spinlock_t lock; > > + u16 cpu; > > trivia: > > What's the real value in not using int here? > On some machines, sizeof(spinlock_t) is 2 So this addition doesn't increase size of the structure, as I fill a hole. Thats the case on x86 when NR_CPUS < 256