From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: [PATCH] netfilter: use per-CPU recursive lock {XIV} Date: Fri, 24 Apr 2009 06:58:39 +0200 Message-ID: <49F146FF.5050200@cosmosbay.com> References: <20090418094001.GA2369@ioremap.net> <20090418141455.GA7082@linux.vnet.ibm.com> <20090420103414.1b4c490f@nehalam> <49ECBE0A.7010303@cosmosbay.com> <18924.59347.375292.102385@cargo.ozlabs.ibm.com> <20090420215827.GK6822@linux.vnet.ibm.com> <18924.64032.103954.171918@cargo.ozlabs.ibm.com> <20090420160121.268a8226@nehalam> <20090421111541.228e977a@nehalam> <20090421193924.GA24404@elte.hu> <20090421143927.52d7d89d@nehalam> <20090423210938.1501507b@nehalam> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Linus Torvalds , Ingo Molnar , Paul Mackerras , paulmck@linux.vnet.ibm.com, Evgeniy Polyakov , David Miller , kaber@trash.net, jeff.chua.linux@gmail.com, laijs@cn.fujitsu.com, jengelh@medozas.de, r000n@r000n.net, linux-kernel@vger.kernel.org, netfilter-devel@vger.kernel.org, netdev@vger.kernel.org, benh@kernel.crashing.org, mathieu.desnoyers@polymtl.ca To: Stephen Hemminger Return-path: In-Reply-To: <20090423210938.1501507b@nehalam> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Stephen Hemminger a =E9crit : > In days of old in 2.6.29, netfilter did locketh using a=20 > lock of the reader kind when doing its table business, and do > a writer when with pen in hand like a overworked accountant > did replace the tables. This sucketh and caused the single > lock to fly back and forth like a poor errant boy. >=20 > But then netfilter was blessed with RCU and the performance > was divine, but alas there were those that suffered for > trying to replace their many rules one at a time. >=20 > So now RCU must be vanquished from the scene, and better > chastity belts be placed upon this valuable asset most dear. > The locks that were but one are now replaced by one per suitor. >=20 > The repair was made after much discussion involving > Eric the wise, and Linus the foul. With flowers springing > up amid the thorns some peace has finally prevailed and > all is soothed. This patch and purple prose was penned by > in honor of "Talk like Shakespeare" day. >=20 > Signed-off-by: Stephen Hemminger Philip Davis of the university=92s School of English said : "Shakespeare surprises the brain and catches it off guard in a manner that produces a sudden burst of activity - a sense=20 of drama created out of the simplest of things." http://www.physorg.com/news85664210.html >=20 > --- > What hath changed over the last two setting suns: > * more words, mostly correct... >=20 > * no need to locketh for writeh on current cpu tis=20 > always so >=20 > * the locking of all cpu's on replace is always done as > part of the get_counters cycle, so the sychronize swip > in replace tables is gone with only a comment remaing >=20 > include/linux/netfilter/x_tables.h | 55 ++++++++++++++-- > net/ipv4/netfilter/arp_tables.c | 125 ++++++++++----------------= ---------- > net/ipv4/netfilter/ip_tables.c | 126 ++++++++++----------------= ----------- > net/ipv6/netfilter/ip6_tables.c | 123 ++++++++++----------------= ---------- > net/netfilter/x_tables.c | 55 ++++++++-------- > 5 files changed, 188 insertions(+), 296 deletions(-) >=20 > =20 > static int __init xt_init(void) > { > - int i, rv; > + unsigned int i; > + int rv; > + static struct lock_class_key xt_lock_key[NR_CPUS]; Could we avoid this [NR_CPUS] thing ? > + > + for_each_possible_cpu(i) { > + rwlock_t *lock =3D &per_cpu(xt_info_locks, i); > + > + rwlock_init(lock); > + lockdep_set_class(lock, xt_lock_key+i); > + } Did you tried : static DECLARE_PER_CPU(struct lock_class_key, xt_locks_key); static int __init xt_init(void) { unsigned int i; int rv; for_each_possible_cpu(i) { rwlock_t *lock =3D &per_cpu(xt_info_locks, i); rwlock_init(lock); lockdep_set_class(lock, &per_cpu(&xt_locks_key, i)); } =2E.. Thanks