This per netns sysctl allows for TCP SACK compression fine-tuning.
Its default value is 1,000,000, or 1 ms to meet TSO autosizing period.
Signed-off-by: Eric Dumazet <eduma...@google.com>
---
Documentation/networking/ip-sysctl.txt | 7 +++++++
include/net/netns/ipv4.h | 1 +
net/ipv4/sysctl_net_ipv4.c | 7 +++++++
net/ipv4/tcp_input.c | 4 ++--
net/ipv4/tcp_ipv4.c | 1 +
5 files changed, 18 insertions(+), 2 deletions(-)
diff --git a/Documentation/networking/ip-sysctl.txt
b/Documentation/networking/ip-sysctl.txt
index
59afc9a10b4f42bac6871f9183f2bac78ca87803..a7d44627d6356171891fb3c0ab5783f69b6dcb3d
100644
--- a/Documentation/networking/ip-sysctl.txt
+++ b/Documentation/networking/ip-sysctl.txt
@@ -523,6 +523,13 @@ tcp_rmem - vector of 3 INTEGERs: min, default, max
tcp_sack - BOOLEAN
Enable select acknowledgments (SACKS).
+tcp_comp_sack_delay_ns - LONG INTEGER
+ TCP tries to reduce number of SACK sent, using a timer
+ based on 5% of SRTT, capped by this sysctl, in nano seconds.
+ The default is 1ms, based on TSO autosizing period.
+
+ Default : 1,000,000 ns (1 ms)
+
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
diff --git a/include/net/netns/ipv4.h b/include/net/netns/ipv4.h
index
8491bc9c86b1553ab603e4363e8e38ca7ff547e0..927318243cfaa2ddd8eb423c6ba6e66253f771d3
100644
--- a/include/net/netns/ipv4.h
+++ b/include/net/netns/ipv4.h
@@ -160,6 +160,7 @@ struct netns_ipv4 {
int sysctl_tcp_pacing_ca_ratio;
int sysctl_tcp_wmem[3];
int sysctl_tcp_rmem[3];
+ unsigned long sysctl_tcp_comp_sack_delay_ns;
struct inet_timewait_death_row tcp_death_row;
int sysctl_max_syn_backlog;
int sysctl_tcp_fastopen;
diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
index
4b195bac8ac0eefe0a224528ad854338c4f8e6e3..11fbfdc1566eca95f91360522178295318277588
100644
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -1151,6 +1151,13 @@ static struct ctl_table ipv4_net_table[] = {
.proc_handler = proc_dointvec_minmax,
.extra1 = &one,
},
+ {
+ .procname = "tcp_comp_sack_delay_ns",
+ .data = &init_net.ipv4.sysctl_tcp_comp_sack_delay_ns,
+ .maxlen = sizeof(unsigned long),
+ .mode = 0644,
+ .proc_handler = proc_doulongvec_minmax,
+ },
{
.procname = "udp_rmem_min",
.data = &init_net.ipv4.sysctl_udp_rmem_min,
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index
2e03c1b4d327558fa4187b9dd53432df2e7d307f..480a647fd5922c1736455e625890da5f85d19ea7
100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -5106,9 +5106,9 @@ static void __tcp_ack_snd_check(struct sock *sk, int
ofo_possible)
if (hrtimer_is_queued(&tp->compressed_ack_timer))
return;
- /* compress ack timer : 5 % of srtt, but no more than 1 ms */
+ /* 5 % of srtt, but no more than tcp_comp_sack_delay_ns */
- delay = min_t(unsigned long, NSEC_PER_MSEC,
+ delay = min_t(unsigned long,
sock_net(sk)->ipv4.sysctl_tcp_comp_sack_delay_ns,
tp->rcv_rtt_est.rtt_us * (NSEC_PER_USEC >> 3)/20);
sock_hold(sk);
hrtimer_start(&tp->compressed_ack_timer, ns_to_ktime(delay),
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index
caf23de88f8a369c2038cecd34ce42c522487e90..a3f4647341db2eb5a63c3e9f1e8b93099aedadab
100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -2572,6 +2572,7 @@ static int __net_init tcp_sk_init(struct net *net)
init_net.ipv4.sysctl_tcp_wmem,
sizeof(init_net.ipv4.sysctl_tcp_wmem));
}
+ net->ipv4.sysctl_tcp_comp_sack_delay_ns = NSEC_PER_MSEC;
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;
--
2.17.0.441.gb46fe60e1d-goog
