On Mon, 13 Apr 2009 19:40:24 +0200 Eric Dumazet <dada1@xxxxxxxxxxxxx> wrote: > Stephen Hemminger a écrit : > > This is an alternative version of ip/ip6/arp tables locking using > > per-cpu locks. This avoids the overhead of synchronize_net() during > > update but still removes the expensive rwlock in earlier versions. > > > > The idea for this came from an earlier version done by Eric Duzamet. > > Locking is done per-cpu, the fast path locks on the current cpu > > and updates counters. The slow case involves acquiring the locks on > > all cpu's. > > > > The mutex that was added for 2.6.30 in xt_table is unnecessary since > > there already is a mutex for xt[af].mutex that is held. > > > > Tested basic functionality (add/remove/list), but don't have test cases > > for stress, ip6tables or arptables. > > > > Signed-off-by: Stephen Hemminger <shemminger@xxxxxxxxxx> > > Patch seems good to me, but apparently xt_replace_table() > misses the "acquiring the locks on all cpus" you mentioned in ChangeLog ? It happens in get_counters already. > I am still off-computers until tomorrow so cannot provide a patch for this, sorry. > > Some form of > > local_bh_disable(); > for_each_possible_cpu(cpu) > spin_lock(&per_cpu(ip_tables_lock, cpu)); > > oldinfo = private; > /* do the substitution */ > table->private = newinfo; > newinfo->initial_entries = oldinfo->initial_entries; > > for_each_possible_cpu(cpu) > spin_unlock(&per_cpu(ip_tables_lock, cpu)); > local_bh_enable(); > > > But I wonder if this could hit a limit of max spinlocks held by this cpu, say on a 4096 cpu machine ? > > > -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
