diff options
| author | Eric Dumazet <edumazet@google.com> | 2015-04-13 04:51:09 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2015-04-13 23:40:05 +0300 |
| commit | 789f558cfb3680aeb52de137418637f6b04b7d22 (patch) | |
| tree | 0031c54a2fe41480ed509ba140a1c12ecad075a6 /net/ipv6 | |
| parent | 20a1d16526b79c76cd45e29cb637aec1d43c41de (diff) | |
| download | linux-789f558cfb3680aeb52de137418637f6b04b7d22.tar.xz | |
tcp/dccp: get rid of central timewait timer
Using a timer wheel for timewait sockets was nice ~15 years ago when
memory was expensive and machines had a single processor.
This does not scale, code is ugly and source of huge latencies
(Typically 30 ms have been seen, cpus spinning on death_lock spinlock.)
We can afford to use an extra 64 bytes per timewait sock and spread
timewait load to all cpus to have better behavior.
Tested:
On following test, /proc/sys/net/ipv4/tcp_tw_recycle is set to 1
on the target (lpaa24)
Before patch :
lpaa23:~# ./super_netperf 200 -H lpaa24 -t TCP_CC -l 60 -- -p0,0
419594
lpaa23:~# ./super_netperf 200 -H lpaa24 -t TCP_CC -l 60 -- -p0,0
437171
While test is running, we can observe 25 or even 33 ms latencies.
lpaa24:~# ping -c 1000 -i 0.02 -qn lpaa23
...
1000 packets transmitted, 1000 received, 0% packet loss, time 20601ms
rtt min/avg/max/mdev = 0.020/0.217/25.771/1.535 ms, pipe 2
lpaa24:~# ping -c 1000 -i 0.02 -qn lpaa23
...
1000 packets transmitted, 1000 received, 0% packet loss, time 20702ms
rtt min/avg/max/mdev = 0.019/0.183/33.761/1.441 ms, pipe 2
After patch :
About 90% increase of throughput :
lpaa23:~# ./super_netperf 200 -H lpaa24 -t TCP_CC -l 60 -- -p0,0
810442
lpaa23:~# ./super_netperf 200 -H lpaa24 -t TCP_CC -l 60 -- -p0,0
800992
And latencies are kept to minimal values during this load, even
if network utilization is 90% higher :
lpaa24:~# ping -c 1000 -i 0.02 -qn lpaa23
...
1000 packets transmitted, 1000 received, 0% packet loss, time 19991ms
rtt min/avg/max/mdev = 0.023/0.064/0.360/0.042 ms
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv6')
| -rw-r--r-- | net/ipv6/inet6_hashtables.c | 2 | ||||
| -rw-r--r-- | net/ipv6/tcp_ipv6.c | 4 |
2 files changed, 3 insertions, 3 deletions
diff --git a/net/ipv6/inet6_hashtables.c b/net/ipv6/inet6_hashtables.c index 033f17816ef4..871641bc1ed4 100644 --- a/net/ipv6/inet6_hashtables.c +++ b/net/ipv6/inet6_hashtables.c @@ -246,7 +246,7 @@ static int __inet6_check_established(struct inet_timewait_death_row *death_row, *twp = tw; } else if (tw) { /* Silly. Should hash-dance instead... */ - inet_twsk_deschedule(tw, death_row); + inet_twsk_deschedule(tw); inet_twsk_put(tw); } diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c index f73a97f6e68e..ad51df85aa00 100644 --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -1486,7 +1486,7 @@ do_time_wait: ntohs(th->dest), tcp_v6_iif(skb)); if (sk2) { struct inet_timewait_sock *tw = inet_twsk(sk); - inet_twsk_deschedule(tw, &tcp_death_row); + inet_twsk_deschedule(tw); inet_twsk_put(tw); sk = sk2; tcp_v6_restore_cb(skb); @@ -1728,9 +1728,9 @@ static void get_tcp6_sock(struct seq_file *seq, struct sock *sp, int i) static void get_timewait6_sock(struct seq_file *seq, struct inet_timewait_sock *tw, int i) { + long delta = tw->tw_timer.expires - jiffies; const struct in6_addr *dest, *src; __u16 destp, srcp; - s32 delta = tw->tw_ttd - inet_tw_time_stamp(); dest = &tw->tw_v6_daddr; src = &tw->tw_v6_rcv_saddr; |