Merge branch 'tcp-receive-side-improvements'

Browse source

Eric Dumazet says:

====================
tcp: receive side improvements

We have set tcp_rmem[2] to 15 MB for about 8 years at Google,
but had some issues for high speed flows on very small RTT.

TCP rx autotuning has a tendency to overestimate the RTT,
thus tp->rcvq_space.space and sk->sk_rcvbuf.

This makes TCP receive queues much bigger than necessary,
to a point cpu caches are evicted before application can
copy the data, on cpus using DDIO.

This series aims to fix this.

- First patch adds tcp_rcvbuf_grow() tracepoint, which was very
  convenient to study the various issues fixed in this series.

- Seven patches fix receiver autotune issues.

- Two patches fix sender side issues.

- Final patch increases tcp_rmem[2] so that TCP speed over WAN
  can meet modern needs.

Tested on a 200Gbit NIC, average max throughput of a single flow:

Before:
 73593 Mbit.

After:
 122514 Mbit.
====================

Link: https://patch.msgid.link/20250513193919.1089692-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

...

This commit is contained in:

Jakub Kicinski 2025-05-15 11:30:11 -07:00

parent bebd7b2626 572be9bf9d

commit 2da35e4b4d

7 changed files with 134 additions and 66 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

4

Documentation/networking/ip-sysctl.rst

View file

2

include/linux/tcp.h

View file

73

include/trace/events/tcp.h

View file

2

net/ipv4/tcp.c

View file

110

net/ipv4/tcp_input.c

View file

4

net/ipv4/tcp_ipv4.c

View file

5

net/ipv4/tcp_output.c

View file