Commit 4707191c authored by Jakub Kicinski's avatar Jakub Kicinski
Browse files

Merge branch 'tcp-tcp_rcvbuf_grow-changes' 

Eric Dumazet says:

====================
tcp: tcp_rcvbuf_grow() changes

First pach is minor and moves tcp_moderate_rcvbuf in appropriate group.

Second patch is another attempt to keep small sk->sk_rcvbuf for DC
(small RT) TCP flows for optimal performance.
====================

Link: https://patch.msgid.link/20251119084813.3684576-1-edumazet@google.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parents 738cd803 ecfea98b

Documentation/networking/ip-sysctl.rst

+10 −0
Original line number Diff line number Diff line
@@ -673,6 +673,16 @@ tcp_moderate_rcvbuf - BOOLEAN 


	Default: 1 (enabled)



tcp_rcvbuf_low_rtt - INTEGER

	rcvbuf autotuning can over estimate final socket rcvbuf, which

	can lead to cache trashing for high throughput flows.



	For small RTT flows (below tcp_rcvbuf_low_rtt usecs), we can relax

	rcvbuf growth: Few additional ms to reach the final (and smaller)

	rcvbuf is a good tradeoff.



	Default : 1000 (1 ms)



tcp_mtu_probing - INTEGER

	Controls TCP Packetization-Layer Path MTU Discovery.  Takes three

	values:

Documentation/networking/net_cachelines/netns_ipv4_sysctl.rst

+2 −1
Original line number Diff line number Diff line
@@ -102,7 +102,8 @@ u8 sysctl_tcp_app_win 
u8                              sysctl_tcp_frto                                                                      tcp_enter_loss

u8                              sysctl_tcp_nometrics_save                                                            TCP_LAST_ACK/tcp_update_metrics

u8                              sysctl_tcp_no_ssthresh_metrics_save                                                  TCP_LAST_ACK/tcp_(update/init)_metrics

u8                              sysctl_tcp_moderate_rcvbuf                   read_mostly         read_mostly         tcp_tso_should_defer(tx);tcp_rcv_space_adjust(rx)

u8                              sysctl_tcp_moderate_rcvbuf                                       read_mostly         tcp_rcvbuf_grow()

u32                             sysctl_tcp_rcvbuf_low_rtt                                        read_mostly         tcp_rcvbuf_grow()

u8                              sysctl_tcp_tso_win_divisor                   read_mostly                             tcp_tso_should_defer(tcp_write_xmit)

u8                              sysctl_tcp_workaround_signed_windows                                                 tcp_select_window

int                             sysctl_tcp_limit_output_bytes                read_mostly                             tcp_small_queue_check(tcp_write_xmit)

include/net/netns/ipv4.h

+2 −1
Original line number Diff line number Diff line
@@ -74,17 +74,18 @@ struct netns_ipv4 { 


	/* TXRX readonly hotpath cache lines */

	__cacheline_group_begin(netns_ipv4_read_txrx);

	u8 sysctl_tcp_moderate_rcvbuf;

	__cacheline_group_end(netns_ipv4_read_txrx);



	/* RX readonly hotpath cache line */

	__cacheline_group_begin(netns_ipv4_read_rx);

	u8 sysctl_tcp_moderate_rcvbuf;

	u8 sysctl_ip_early_demux;

	u8 sysctl_tcp_early_demux;

	u8 sysctl_tcp_l3mdev_accept;

	/* 3 bytes hole, try to pack */

	int sysctl_tcp_reordering;

	int sysctl_tcp_rmem[3];

	int sysctl_tcp_rcvbuf_low_rtt;

	__cacheline_group_end(netns_ipv4_read_rx);



	struct inet_timewait_death_row tcp_death_row;

net/core/net_namespace.c

+4 −7
Original line number Diff line number Diff line
@@ -1223,14 +1223,12 @@ static void __init netns_ipv4_struct_check(void) 
				      sysctl_tcp_wmem);

	CACHELINE_ASSERT_GROUP_MEMBER(struct netns_ipv4, netns_ipv4_read_tx,

				      sysctl_ip_fwd_use_pmtu);

	CACHELINE_ASSERT_GROUP_SIZE(struct netns_ipv4, netns_ipv4_read_tx, 33);



	/* TXRX readonly hotpath cache lines */

	CACHELINE_ASSERT_GROUP_MEMBER(struct netns_ipv4, netns_ipv4_read_txrx,

				      sysctl_tcp_moderate_rcvbuf);

	CACHELINE_ASSERT_GROUP_SIZE(struct netns_ipv4, netns_ipv4_read_txrx, 1);



	/* RX readonly hotpath cache line */

	CACHELINE_ASSERT_GROUP_MEMBER(struct netns_ipv4, netns_ipv4_read_rx,

				      sysctl_tcp_moderate_rcvbuf);

	CACHELINE_ASSERT_GROUP_MEMBER(struct netns_ipv4, netns_ipv4_read_rx,

				      sysctl_tcp_rcvbuf_low_rtt);

	CACHELINE_ASSERT_GROUP_MEMBER(struct netns_ipv4, netns_ipv4_read_rx,

				      sysctl_ip_early_demux);

	CACHELINE_ASSERT_GROUP_MEMBER(struct netns_ipv4, netns_ipv4_read_rx,
@@ -1241,7 +1239,6 @@ static void __init netns_ipv4_struct_check(void) 
				      sysctl_tcp_reordering);

	CACHELINE_ASSERT_GROUP_MEMBER(struct netns_ipv4, netns_ipv4_read_rx,

				      sysctl_tcp_rmem);

	CACHELINE_ASSERT_GROUP_SIZE(struct netns_ipv4, netns_ipv4_read_rx, 22);

}

#endif

net/ipv4/sysctl_net_ipv4.c

+9 −0
Original line number Diff line number Diff line
@@ -1342,6 +1342,15 @@ static struct ctl_table ipv4_net_table[] = { 
		.mode		= 0644,

		.proc_handler	= proc_dou8vec_minmax,

	},

	{

		.procname	= "tcp_rcvbuf_low_rtt",

		.data		= &init_net.ipv4.sysctl_tcp_rcvbuf_low_rtt,

		.maxlen		= sizeof(int),

		.mode		= 0644,

		.proc_handler	= proc_dointvec_minmax,

		.extra1		= SYSCTL_ZERO,

		.extra2		= SYSCTL_INT_MAX,

	},

	{

		.procname	= "tcp_tso_win_divisor",

		.data		= &init_net.ipv4.sysctl_tcp_tso_win_divisor,