Re: [PATCH] netfilter: use per-cpu spinlock rather than RCU

Patrick McHardy
2009-04-14T12:27:59Z

Stephen Hemminger wrote:
> 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.

Thanks Stephen, I'll do some testing with ip6tables.