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author | Jesper Dangaard Brouer <brouer@redhat.com> | 2014-03-03 14:46:13 +0100 |
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committer | Pablo Neira Ayuso <pablo@netfilter.org> | 2014-03-07 11:41:13 +0100 |
commit | 93bb0ceb75be2fdfa9fc0dd1fb522d9ada515d9c (patch) | |
tree | e47e7b701d8aa47683816a2d913ad7d005c25939 /include/net/netfilter | |
parent | ca7433df3a672efc88e08222cfa4b3aa965ca324 (diff) | |
download | linux-stable-93bb0ceb75be2fdfa9fc0dd1fb522d9ada515d9c.tar.gz linux-stable-93bb0ceb75be2fdfa9fc0dd1fb522d9ada515d9c.tar.bz2 linux-stable-93bb0ceb75be2fdfa9fc0dd1fb522d9ada515d9c.zip |
netfilter: conntrack: remove central spinlock nf_conntrack_lock
nf_conntrack_lock is a monolithic lock and suffers from huge contention
on current generation servers (8 or more core/threads).
Perf locking congestion is clear on base kernel:
- 72.56% ksoftirqd/6 [kernel.kallsyms] [k] _raw_spin_lock_bh
- _raw_spin_lock_bh
+ 25.33% init_conntrack
+ 24.86% nf_ct_delete_from_lists
+ 24.62% __nf_conntrack_confirm
+ 24.38% destroy_conntrack
+ 0.70% tcp_packet
+ 2.21% ksoftirqd/6 [kernel.kallsyms] [k] fib_table_lookup
+ 1.15% ksoftirqd/6 [kernel.kallsyms] [k] __slab_free
+ 0.77% ksoftirqd/6 [kernel.kallsyms] [k] inet_getpeer
+ 0.70% ksoftirqd/6 [nf_conntrack] [k] nf_ct_delete
+ 0.55% ksoftirqd/6 [ip_tables] [k] ipt_do_table
This patch change conntrack locking and provides a huge performance
improvement. SYN-flood attack tested on a 24-core E5-2695v2(ES) with
10Gbit/s ixgbe (with tool trafgen):
Base kernel: 810.405 new conntrack/sec
After patch: 2.233.876 new conntrack/sec
Notice other floods attack (SYN+ACK or ACK) can easily be deflected using:
# iptables -A INPUT -m state --state INVALID -j DROP
# sysctl -w net/netfilter/nf_conntrack_tcp_loose=0
Use an array of hashed spinlocks to protect insertions/deletions of
conntracks into the hash table. 1024 spinlocks seem to give good
results, at minimal cost (4KB memory). Due to lockdep max depth,
1024 becomes 8 if CONFIG_LOCKDEP=y
The hash resize is a bit tricky, because we need to take all locks in
the array. A seqcount_t is used to synchronize the hash table users
with the resizing process.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Reviewed-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'include/net/netfilter')
-rw-r--r-- | include/net/netfilter/nf_conntrack_core.h | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/include/net/netfilter/nf_conntrack_core.h b/include/net/netfilter/nf_conntrack_core.h index d12a631d0415..cc0c18827602 100644 --- a/include/net/netfilter/nf_conntrack_core.h +++ b/include/net/netfilter/nf_conntrack_core.h @@ -77,7 +77,12 @@ print_tuple(struct seq_file *s, const struct nf_conntrack_tuple *tuple, const struct nf_conntrack_l3proto *l3proto, const struct nf_conntrack_l4proto *proto); -extern spinlock_t nf_conntrack_lock ; +#ifdef CONFIG_LOCKDEP +# define CONNTRACK_LOCKS 8 +#else +# define CONNTRACK_LOCKS 1024 +#endif +extern spinlock_t nf_conntrack_locks[CONNTRACK_LOCKS]; extern spinlock_t nf_conntrack_expect_lock; |