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 <eduma...@google.com> --- Documentation/networking/ip-sysctl.txt | 6 ++++++ include/net/netns/ipv4.h | 1 + net/ipv4/sysctl_net_ipv4.c | 10 ++++++++++ net/ipv4/tcp_input.c | 3 ++- net/ipv4/tcp_ipv4.c | 1 + 5 files changed, 20 insertions(+), 1 deletion(-) diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt index a7d44627d6356171891fb3c0ab5783f69b6dcb3d..e46fe037da48ace9bb03bb61690fb238601c3558 100644 --- a/Documentation/networking/ip-sysctl.txt +++ b/Documentation/networking/ip-sysctl.txt @@ -530,6 +530,12 @@ 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 diff --git a/include/net/netns/ipv4.h b/include/net/netns/ipv4.h index 927318243cfaa2ddd8eb423c6ba6e66253f771d3..661348f23ea5a3a9320b2cafcd17e23960214771 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]; + 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; diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c index 11fbfdc1566eca95f91360522178295318277588..d2eed3ddcb0a1ad9778d96d46c685f6c60b93d8d 100644 --- a/net/ipv4/sysctl_net_ipv4.c +++ b/net/ipv4/sysctl_net_ipv4.c @@ -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, diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 480a647fd5922c1736455e625890da5f85d19ea7..f763637e83c7412da73cea77b0eae4076e90ca6a 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -5099,7 +5099,8 @@ static void __tcp_ack_snd_check(struct sock *sk, int ofo_possible) 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++; diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index a3f4647341db2eb5a63c3e9f1e8b93099aedadab..adbdb503db0c983ef4185f83b138aa51bafd15bf 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -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; -- 2.17.0.441.gb46fe60e1d-goog