diff options
| -rw-r--r-- | Documentation/networking/ip-sysctl.rst | 7 | ||||
| -rw-r--r-- | include/linux/tcp.h | 14 | ||||
| -rw-r--r-- | include/net/netns/ipv4.h | 1 | ||||
| -rw-r--r-- | net/ipv4/sysctl_net_ipv4.c | 9 | ||||
| -rw-r--r-- | net/ipv4/tcp_input.c | 8 | ||||
| -rw-r--r-- | net/ipv4/tcp_ipv4.c | 1 | ||||
| -rw-r--r-- | net/ipv4/tcp_output.c | 5 |
7 files changed, 38 insertions, 7 deletions
diff --git a/Documentation/networking/ip-sysctl.rst b/Documentation/networking/ip-sysctl.rst index a66054d0763a..5bfa1837968c 100644 --- a/Documentation/networking/ip-sysctl.rst +++ b/Documentation/networking/ip-sysctl.rst @@ -745,6 +745,13 @@ tcp_comp_sack_nr - INTEGER Default : 44 +tcp_backlog_ack_defer - BOOLEAN + If set, user thread processing socket backlog tries sending + one ACK for the whole queue. This helps to avoid potential + long latencies at end of a TCP socket syscall. + + Default : true + 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/linux/tcp.h b/include/linux/tcp.h index 3c5efeeb024f..44d946161d4a 100644 --- a/include/linux/tcp.h +++ b/include/linux/tcp.h @@ -463,15 +463,17 @@ enum tsq_enum { TCP_MTU_REDUCED_DEFERRED, /* tcp_v{4|6}_err() could not call * tcp_v{4|6}_mtu_reduced() */ + TCP_ACK_DEFERRED, /* TX pure ack is deferred */ }; enum tsq_flags { - TSQF_THROTTLED = (1UL << TSQ_THROTTLED), - TSQF_QUEUED = (1UL << TSQ_QUEUED), - TCPF_TSQ_DEFERRED = (1UL << TCP_TSQ_DEFERRED), - TCPF_WRITE_TIMER_DEFERRED = (1UL << TCP_WRITE_TIMER_DEFERRED), - TCPF_DELACK_TIMER_DEFERRED = (1UL << TCP_DELACK_TIMER_DEFERRED), - TCPF_MTU_REDUCED_DEFERRED = (1UL << TCP_MTU_REDUCED_DEFERRED), + TSQF_THROTTLED = BIT(TSQ_THROTTLED), + TSQF_QUEUED = BIT(TSQ_QUEUED), + TCPF_TSQ_DEFERRED = BIT(TCP_TSQ_DEFERRED), + TCPF_WRITE_TIMER_DEFERRED = BIT(TCP_WRITE_TIMER_DEFERRED), + TCPF_DELACK_TIMER_DEFERRED = BIT(TCP_DELACK_TIMER_DEFERRED), + TCPF_MTU_REDUCED_DEFERRED = BIT(TCP_MTU_REDUCED_DEFERRED), + TCPF_ACK_DEFERRED = BIT(TCP_ACK_DEFERRED), }; #define tcp_sk(ptr) container_of_const(ptr, struct tcp_sock, inet_conn.icsk_inet.sk) diff --git a/include/net/netns/ipv4.h b/include/net/netns/ipv4.h index 7a41c4791536..d96d05b08819 100644 --- a/include/net/netns/ipv4.h +++ b/include/net/netns/ipv4.h @@ -132,6 +132,7 @@ struct netns_ipv4 { u8 sysctl_tcp_syncookies; u8 sysctl_tcp_migrate_req; u8 sysctl_tcp_comp_sack_nr; + u8 sysctl_tcp_backlog_ack_defer; int sysctl_tcp_reordering; u8 sysctl_tcp_retries1; u8 sysctl_tcp_retries2; diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c index 6ac890b4073f..e7f024d93572 100644 --- a/net/ipv4/sysctl_net_ipv4.c +++ b/net/ipv4/sysctl_net_ipv4.c @@ -1367,6 +1367,15 @@ static struct ctl_table ipv4_net_table[] = { .extra1 = SYSCTL_ZERO, }, { + .procname = "tcp_backlog_ack_defer", + .data = &init_net.ipv4.sysctl_tcp_backlog_ack_defer, + .maxlen = sizeof(u8), + .mode = 0644, + .proc_handler = proc_dou8vec_minmax, + .extra1 = SYSCTL_ZERO, + .extra2 = SYSCTL_ONE, + }, + { .procname = "tcp_reflect_tos", .data = &init_net.ipv4.sysctl_tcp_reflect_tos, .maxlen = sizeof(u8), diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 06fe1cf645d5..41b471748437 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -5553,6 +5553,14 @@ static void __tcp_ack_snd_check(struct sock *sk, int ofo_possible) tcp_in_quickack_mode(sk) || /* Protocol state mandates a one-time immediate ACK */ inet_csk(sk)->icsk_ack.pending & ICSK_ACK_NOW) { + /* If we are running from __release_sock() in user context, + * Defer the ack until tcp_release_cb(). + */ + if (sock_owned_by_user_nocheck(sk) && + READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_backlog_ack_defer)) { + set_bit(TCP_ACK_DEFERRED, &sk->sk_tsq_flags); + return; + } send_now: tcp_send_ack(sk); return; diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index 27140e5cdc06..f13eb7e23d03 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -3263,6 +3263,7 @@ static int __net_init tcp_sk_init(struct net *net) net->ipv4.sysctl_tcp_comp_sack_delay_ns = NSEC_PER_MSEC; net->ipv4.sysctl_tcp_comp_sack_slack_ns = 100 * NSEC_PER_USEC; net->ipv4.sysctl_tcp_comp_sack_nr = 44; + net->ipv4.sysctl_tcp_backlog_ack_defer = 1; net->ipv4.sysctl_tcp_fastopen = TFO_CLIENT_ENABLE; net->ipv4.sysctl_tcp_fastopen_blackhole_timeout = 0; atomic_set(&net->ipv4.tfo_active_disable_times, 0); diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index b4cac12d0e63..1fc1f879cfd6 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -1077,7 +1077,8 @@ static void tcp_tasklet_func(struct tasklet_struct *t) #define TCP_DEFERRED_ALL (TCPF_TSQ_DEFERRED | \ TCPF_WRITE_TIMER_DEFERRED | \ TCPF_DELACK_TIMER_DEFERRED | \ - TCPF_MTU_REDUCED_DEFERRED) + TCPF_MTU_REDUCED_DEFERRED | \ + TCPF_ACK_DEFERRED) /** * tcp_release_cb - tcp release_sock() callback * @sk: socket @@ -1114,6 +1115,8 @@ void tcp_release_cb(struct sock *sk) inet_csk(sk)->icsk_af_ops->mtu_reduced(sk); __sock_put(sk); } + if ((flags & TCPF_ACK_DEFERRED) && inet_csk_ack_scheduled(sk)) + tcp_send_ack(sk); } EXPORT_SYMBOL(tcp_release_cb); |