netdev - [PATCH net-next 11/11] tcp: increase tcp

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Message-ID: <20250513193919.1089692-12-edumazet@google.com>
Date: Tue, 13 May 2025 19:39:19 +0000
From: Eric Dumazet <edumazet@...gle.com>
To: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, 
	Paolo Abeni <pabeni@...hat.com>, Neal Cardwell <ncardwell@...gle.com>
Cc: Simon Horman <horms@...nel.org>, Kuniyuki Iwashima <kuniyu@...zon.com>, 
	Rick Jones <jonesrick@...gle.com>, Wei Wang <weiwan@...gle.com>, netdev@...r.kernel.org, 
	eric.dumazet@...il.com, Eric Dumazet <edumazet@...gle.com>
Subject: [PATCH net-next 11/11] tcp: increase tcp_rmem[2] to 32 MB

Last change to tcp_rmem[2] happened in 2012, in commit b49960a05e32
("tcp: change tcp_adv_win_scale and tcp_rmem[2]")

TCP performance on WAN is mostly limited by tcp_rmem[2] for receivers.

After this series improvements, it is time to increase the default.

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 Documentation/networking/ip-sysctl.rst | 2 +-
 net/ipv4/tcp.c                         | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/Documentation/networking/ip-sysctl.rst b/Documentation/networking/ip-sysctl.rst
index 91b7d0a1c7fd884ee964d5be0d4dbd10ce040f76..0f1251cce31491930c3e446ae746e538d22fc5c7 100644
--- a/Documentation/networking/ip-sysctl.rst
+++ b/Documentation/networking/ip-sysctl.rst
@@ -735,7 +735,7 @@ tcp_rmem - vector of 3 INTEGERs: min, default, max
 	net.core.rmem_max.  Calling setsockopt() with SO_RCVBUF disables
 	automatic tuning of that socket's receive buffer size, in which
 	case this value is ignored.
-	Default: between 131072 and 6MB, depending on RAM size.
+	Default: between 131072 and 32MB, depending on RAM size.
 
 tcp_sack - BOOLEAN
 	Enable select acknowledgments (SACKS).
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 0ae265d39184ed1a40a724a1ad6bb8f2f22d4fff..b7b6ab41b496f98bf82e099fab1da454dce1fe67 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -5231,7 +5231,7 @@ void __init tcp_init(void)
 	/* Set per-socket limits to no more than 1/128 the pressure threshold */
 	limit = nr_free_buffer_pages() << (PAGE_SHIFT - 7);
 	max_wshare = min(4UL*1024*1024, limit);
-	max_rshare = min(6UL*1024*1024, limit);
+	max_rshare = min(32UL*1024*1024, limit);
 
 	init_net.ipv4.sysctl_tcp_wmem[0] = PAGE_SIZE;
 	init_net.ipv4.sysctl_tcp_wmem[1] = 16*1024;
-- 
2.49.0.1045.g170613ef41-goog