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Commit 9c21d2fc authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

tcp: add tcp_comp_sack_nr sysctl 



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: 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 6d82aa24

Documentation/networking/ip-sysctl.txt

+6 −0
Original line number Diff line number Diff line
@@ -532,6 +532,12 @@ 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

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];

	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;

net/ipv4/sysctl_net_ipv4.c

+10 −0
Original line number Diff line number Diff line
@@ -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,

net/ipv4/tcp_input.c

+2 −1
Original line number Diff line number Diff line
@@ -5106,7 +5106,8 @@ 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++;

net/ipv4/tcp_ipv4.c

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