From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jarek Poplawski Subject: Re: weird problem Date: Sat, 11 Jul 2009 08:24:55 +0200 Message-ID: <20090711062455.GA3095@ami.dom.local> References: <20090708223459.GB3666@ami.dom.local> <4A5679CC.800@itcare.pl> <4A568444.7010307@itcare.pl> <20090710144754.GA25385@ami.dom.local> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-2 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Eric Dumazet , Eric Dumazet , Linux Network Development list To: =?iso-8859-2?Q?Pawe=B3?= Staszewski Return-path: Received: from mail-fx0-f218.google.com ([209.85.220.218]:43750 "EHLO mail-fx0-f218.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751475AbZGKGZS (ORCPT ); Sat, 11 Jul 2009 02:25:18 -0400 Received: by fxm18 with SMTP id 18so1285084fxm.37 for ; Fri, 10 Jul 2009 23:25:16 -0700 (PDT) Content-Disposition: inline In-Reply-To: <20090710144754.GA25385@ami.dom.local> Sender: netdev-owner@vger.kernel.org List-ID: On Fri, Jul 10, 2009 at 04:47:54PM +0200, Jarek Poplawski wrote: > On Fri, Jul 10, 2009 at 01:59:00AM +0200, Pawe=B3 Staszewski wrote: > > Today i make other tests with change of =20 > > /proc/sys/net/ipv4/rt_cache_rebuild_count and kernel 2.6.30.1 > > > > And when rt_cache_rebuild_count is set to "-1" i have always load o= n =20 > > x86_64 machine approx 40-50% of each cpu where network card is bind= ed by =20 > > irq_aff > > > > when rt_cache_rebuild_count is set to more than "-1" i have 15 to 2= 0 sec =20 > > of 1 to 3% cpu and after 40-50% cpu > ... >=20 > Here is one more patch for testing (with caution!). It adds possibili= ty > to turn off cache disabling (so it should even more resemble 2.6.28) > after setting: rt_cache_rebuild_count =3D 0 >=20 > I'd like you to try this patch: > 1) together with the previous patch and "rt_cache_rebuild_count =3D 0= " > to check if there is still the difference wrt. 2.6.28; Btw., let > me know which /proc/sys/net/ipv4/route/* settings do you need to > change and why >=20 > 2) alone (without the previous patch) and "rt_cache_rebuild_count =3D= 0" >=20 > 3) if it's possible to try 2.6.30.1 without these patches, but with > default /proc/sys/net/ipv4/route/* settings, and higher > rt_cache_rebuild_count, e.g. 100; I'm interested if/how long it > takes to trigger higher cpu load and the warning "... rebuilds is > over limit, route caching disabled"; (Btw., I wonder why you didn'= t > mention about these or maybe also other route caching warnings?) Here is take 2 to respect setting "rt_cache_rebuild_count =3D 0" even after cache rebuild counter has been increased earlier. (Btw, don't forget about this setting after going back to vanilla kernel.) Jarek P. --- (debugging patch #2 take 2; apply to 2.6.30.1 or 2.6.29.6) net/ipv4/route.c | 21 ++++++++++++++------- 1 files changed, 14 insertions(+), 7 deletions(-) diff --git a/net/ipv4/route.c b/net/ipv4/route.c index 278f46f..f74db20 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -678,8 +678,9 @@ static inline u32 rt_score(struct rtable *rt) =20 static inline bool rt_caching(const struct net *net) { - return net->ipv4.current_rt_cache_rebuild_count <=3D - net->ipv4.sysctl_rt_cache_rebuild_count; + return (net->ipv4.current_rt_cache_rebuild_count <=3D + net->ipv4.sysctl_rt_cache_rebuild_count) || + net->ipv4.sysctl_rt_cache_rebuild_count =3D=3D 0; } =20 static inline bool compare_hash_inputs(const struct flowi *fl1, @@ -1181,12 +1182,18 @@ restart: } else { if (chain_length > rt_chain_length_max) { struct net *net =3D dev_net(rt->u.dst.dev); - int num =3D ++net->ipv4.current_rt_cache_rebuild_count; - if (!rt_caching(dev_net(rt->u.dst.dev))) { - printk(KERN_WARNING "%s: %d rebuilds is over limit, route caching = disabled\n", - rt->u.dst.dev->name, num); + + if (net->ipv4.sysctl_rt_cache_rebuild_count > 0) { + int num =3D ++net->ipv4.current_rt_cache_rebuild_count; + + if (!rt_caching(net)) + printk(KERN_WARNING + "%s: %d rebuilds is over limit, " + "route caching disabled\n", + rt->u.dst.dev->name, num); + + rt_emergency_hash_rebuild(net); } - rt_emergency_hash_rebuild(dev_net(rt->u.dst.dev)); } } =20