Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 6d82aa24 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

tcp: add tcp_comp_sack_delay_ns sysctl 



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: default avatarEric Dumazet <edumazet@google.com>
Acked-by: default avatarNeal Cardwell <ncardwell@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 200d95f4

Documentation/networking/ip-sysctl.txt

+7 −0
Original line number Diff line number Diff line
@@ -525,6 +525,13 @@ 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

include/net/netns/ipv4.h

+1 −0
Original line number Diff line number Diff line
@@ -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;

net/ipv4/sysctl_net_ipv4.c

+7 −0
Original line number Diff line number Diff line
@@ -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,

net/ipv4/tcp_input.c

+2 −2
Original line number Diff line number Diff line
@@ -5113,13 +5113,13 @@ 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 rtt, but no more than 1 ms */

	/* compress ack timer : 5 % of rtt, but no more than tcp_comp_sack_delay_ns */



	rtt = tp->rcv_rtt_est.rtt_us;

	if (tp->srtt_us && tp->srtt_us < rtt)

		rtt = tp->srtt_us;



	delay = min_t(unsigned long, NSEC_PER_MSEC,

	delay = min_t(unsigned long, sock_net(sk)->ipv4.sysctl_tcp_comp_sack_delay_ns,

		      rtt * (NSEC_PER_USEC >> 3)/20);

	sock_hold(sk);

	hrtimer_start(&tp->compressed_ack_timer, ns_to_ktime(delay),

net/ipv4/tcp_ipv4.c

+1 −0
Original line number Diff line number Diff line
@@ -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;