Stephen Hemminger a écrit : > The reader/writer lock in ip_tables is acquired in the critical path of > processing packets and is one of the reasons just loading iptables can cause > a 20% performance loss. The rwlock serves two functions: > > 1) it prevents changes to table state (xt_replace) while table is in use. > This is now handled by doing rcu on the xt_table. When table is > replaced, the new table(s) are put in and the old one table(s) are freed > after RCU period. > > 2) it provides synchronization when accesing the counter values. > This is now handled by swapping in new table_info entries for each cpu > then summing the old values, and putting the result back onto one > cpu. On a busy system it may cause sampling to occur at different > times on each cpu, but no packet/byte counts are lost in the process. > > Signed-off-by: Stephen Hemminger <shemminger@xxxxxxxxxx> Acked-by: Eric Dumazet <dada1@xxxxxxxxxxxxx> Sucessfully tested on my dual quad core machine too, but iptables only (no ipv6 here) BTW, my new "tbench 8" result is 2450 MB/s, (it was 2150 MB/s not so long ago) Thanks Stephen, thats very cool stuff, yet another rwlock out of kernel :) > > --- > Added missing preempt_enable. Patch against nf-next-2.6 git tree. > > include/linux/netfilter/x_tables.h | 6 + > net/ipv4/netfilter/arp_tables.c | 115 +++++++++++++++++++++++++++-------- > net/ipv4/netfilter/ip_tables.c | 120 ++++++++++++++++++++++++++----------- > net/ipv6/netfilter/ip6_tables.c | 119 +++++++++++++++++++++++++----------- > net/netfilter/x_tables.c | 26 ++++++-- > 5 files changed, 284 insertions(+), 102 deletions(-) > -- 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
