diff options
| author | Kuniyuki Iwashima <kuniyu@amazon.com> | 2022-09-08 04:10:18 +0300 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2022-09-20 20:21:49 +0300 |
| commit | e9bd0cca09d13ac2f08d25e195203e42d4ad1ce8 (patch) | |
| tree | c098713403c2ed7e70d310348766a1acf9d5e374 /include | |
| parent | 08eaef90403110e51861d93e8008a355af467bbe (diff) | |
| download | linux-e9bd0cca09d13ac2f08d25e195203e42d4ad1ce8.tar.xz | |
tcp: Don't allocate tcp_death_row outside of struct netns_ipv4.
We will soon introduce an optional per-netns ehash and access hash
tables via net->ipv4.tcp_death_row->hashinfo instead of &tcp_hashinfo
in most places.
It could harm the fast path because dereferences of two fields in net
and tcp_death_row might incur two extra cache line misses. To save one
dereference, let's place tcp_death_row back in netns_ipv4 and fetch
hashinfo via net->ipv4.tcp_death_row"."hashinfo.
Note tcp_death_row was initially placed in netns_ipv4, and commit
fbb8295248e1 ("tcp: allocate tcp_death_row outside of struct netns_ipv4")
changed it to a pointer so that we can fire TIME_WAIT timers after freeing
net. However, we don't do so after commit 04c494e68a13 ("Revert "tcp/dccp:
get rid of inet_twsk_purge()""), so we need not define tcp_death_row as a
pointer.
Also, we move refcount_dec_and_test(&tw_refcount) from tcp_sk_exit() to
tcp_sk_exit_batch() as a debug check.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/net/netns/ipv4.h | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/include/net/netns/ipv4.h b/include/net/netns/ipv4.h index 6320a76cefdc..2c7df93e3403 100644 --- a/include/net/netns/ipv4.h +++ b/include/net/netns/ipv4.h @@ -34,6 +34,7 @@ struct inet_hashinfo; struct inet_timewait_death_row { refcount_t tw_refcount; + /* Padding to avoid false sharing, tw_refcount can be often written */ struct inet_hashinfo *hashinfo ____cacheline_aligned_in_smp; int sysctl_max_tw_buckets; }; @@ -41,7 +42,7 @@ struct inet_timewait_death_row { struct tcp_fastopen_context; struct netns_ipv4 { - struct inet_timewait_death_row *tcp_death_row; + struct inet_timewait_death_row tcp_death_row; #ifdef CONFIG_SYSCTL struct ctl_table_header *forw_hdr; |