Commit 9ea3bfa6 authored by Eric Dumazet's avatar Eric Dumazet Committed by Jakub Kicinski
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tcp: increase tcp_limit_output_bytes default value to 4MB 



Last change happened in 2018 with commit c73e5807
("tcp: tsq: no longer use limit_output_bytes for paced flows")

Modern NIC speeds got a 4x increase since then.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20250513193919.1089692-10-edumazet@google.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent a00f135c

Documentation/networking/ip-sysctl.rst

+1 −1
Original line number Diff line number Diff line
@@ -1099,7 +1099,7 @@ tcp_limit_output_bytes - INTEGER 
	limits the number of bytes on qdisc or device to reduce artificial

	RTT/cwnd and reduce bufferbloat.



	Default: 1048576 (16 * 65536)

	Default: 4194304 (4 MB)



tcp_challenge_ack_limit - INTEGER

	Limits number of Challenge ACK sent per second, as recommended

net/ipv4/tcp_ipv4.c

+2 −2
Original line number Diff line number Diff line
@@ -3495,8 +3495,8 @@ static int __net_init tcp_sk_init(struct net *net) 
	 * which are too large can cause TCP streams to be bursty.

	 */

	net->ipv4.sysctl_tcp_tso_win_divisor = 3;

	/* Default TSQ limit of 16 TSO segments */

	net->ipv4.sysctl_tcp_limit_output_bytes = 16 * 65536;

	/* Default TSQ limit of 4 MB */

	net->ipv4.sysctl_tcp_limit_output_bytes = 4 << 20;



	/* rfc5961 challenge ack rate limiting, per net-ns, disabled by default. */

	net->ipv4.sysctl_tcp_challenge_ack_limit = INT_MAX;