mirror of https://github.com/torvalds/linux.git
93bb0ceb75
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>
|
||
|---|---|---|
| .. | ||
| ipv4 | ||
| ipv6 | ||
| nf_conntrack.h | ||
| nf_conntrack_acct.h | ||
| nf_conntrack_core.h | ||
| nf_conntrack_ecache.h | ||
| nf_conntrack_expect.h | ||
| nf_conntrack_extend.h | ||
| nf_conntrack_helper.h | ||
| nf_conntrack_l3proto.h | ||
| nf_conntrack_l4proto.h | ||
| nf_conntrack_labels.h | ||
| nf_conntrack_seqadj.h | ||
| nf_conntrack_synproxy.h | ||
| nf_conntrack_timeout.h | ||
| nf_conntrack_timestamp.h | ||
| nf_conntrack_tuple.h | ||
| nf_conntrack_zones.h | ||
| nf_log.h | ||
| nf_nat.h | ||
| nf_nat_core.h | ||
| nf_nat_helper.h | ||
| nf_nat_l3proto.h | ||
| nf_nat_l4proto.h | ||
| nf_queue.h | ||
| nf_tables.h | ||
| nf_tables_core.h | ||
| nf_tables_ipv4.h | ||
| nf_tables_ipv6.h | ||
| nfnetlink_log.h | ||
| nfnetlink_queue.h | ||
| nft_reject.h | ||
| xt_log.h | ||
| xt_rateest.h | ||