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
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)
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;
.proc_handler = proc_dou8vec_minmax,
.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,
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;
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);
#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
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);