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tcp: add tcp_comp_sack_nr sysctl

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This per netns sysctl allows for TCP SACK compression fine-tuning.

This limits number of SACK that can be compressed.
Using 0 disables SACK compression.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2018-05-17 14:47:29 -07:00 committed by David S. Miller
parent 6d82aa2420
commit 9c21d2fc41
5 changed files with 20 additions and 1 deletions
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6
Documentation/networking/ip-sysctl.txt
View file

@ -532,6 +532,12 @@ tcp_comp_sack_delay_ns - LONG INTEGER
Default : 1,000,000 ns (1 ms)
tcp_comp_sack_nr - INTEGER
Max numer of SACK that can be compressed.
Using 0 disables SACK compression.
Detault : 44
tcp_slow_start_after_idle - BOOLEAN
If set, provide RFC2861 behavior and time out the congestion
window after an idle period. An idle period is defined at

1
include/net/netns/ipv4.h
View file

@ -160,6 +160,7 @@ struct netns_ipv4 {
int sysctl_tcp_pacing_ca_ratio;
int sysctl_tcp_wmem[3];
int sysctl_tcp_rmem[3];
int sysctl_tcp_comp_sack_nr;
unsigned long sysctl_tcp_comp_sack_delay_ns;
struct inet_timewait_death_row tcp_death_row;
int sysctl_max_syn_backlog;

10
net/ipv4/sysctl_net_ipv4.c
View file

@ -46,6 +46,7 @@ static int tcp_syn_retries_min = 1;
static int tcp_syn_retries_max = MAX_TCP_SYNCNT;
static int ip_ping_group_range_min[] = { 0, 0 };
static int ip_ping_group_range_max[] = { GID_T_MAX, GID_T_MAX };
static int comp_sack_nr_max = 255;
/* obsolete */
static int sysctl_tcp_low_latency __read_mostly;
@ -1158,6 +1159,15 @@ static struct ctl_table ipv4_net_table[] = {
.mode = 0644,
.proc_handler = proc_doulongvec_minmax,
},
{
.procname = "tcp_comp_sack_nr",
.data = &init_net.ipv4.sysctl_tcp_comp_sack_nr,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec_minmax,
.extra1 = &zero,
.extra2 = &comp_sack_nr_max,
},
{
.procname = "udp_rmem_min",
.data = &init_net.ipv4.sysctl_udp_rmem_min,

3
net/ipv4/tcp_input.c
View file

@ -5106,7 +5106,8 @@ send_now:
return;
}
if (!tcp_is_sack(tp) || tp->compressed_ack >= 44)
if (!tcp_is_sack(tp) ||
tp->compressed_ack >= sock_net(sk)->ipv4.sysctl_tcp_comp_sack_nr)
goto send_now;
tp->compressed_ack++;

1
net/ipv4/tcp_ipv4.c
View file

@ -2573,6 +2573,7 @@ static int __net_init tcp_sk_init(struct net *net)
sizeof(init_net.ipv4.sysctl_tcp_wmem));
}
net->ipv4.sysctl_tcp_comp_sack_delay_ns = NSEC_PER_MSEC;
net->ipv4.sysctl_tcp_comp_sack_nr = 44;
net->ipv4.sysctl_tcp_fastopen = TFO_CLIENT_ENABLE;
spin_lock_init(&net->ipv4.tcp_fastopen_ctx_lock);
net->ipv4.sysctl_tcp_fastopen_blackhole_timeout = 60 * 60;