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Filename Latest commit message Latest commit date
Maciej Żenczykowski 79e9fed460 net-tcp: extend tcp_tw_reuse sysctl to enable loopback only optimization
This changes the /proc/sys/net/ipv4/tcp_tw_reuse from a boolean
to an integer.

It now takes the values 0, 1 and 2, where 0 and 1 behave as before,
while 2 enables timewait socket reuse only for sockets that we can
prove are loopback connections:
  ie. bound to 'lo' interface or where one of source or destination
  IPs is 127.0.0.0/8, ::ffff:127.0.0.0/104 or ::1.

This enables quicker reuse of ephemeral ports for loopback connections
- where tcp_tw_reuse is 100% safe from a protocol perspective
(this assumes no artificially induced packet loss on 'lo').

This also makes estblishing many loopback connections *much* faster
(allocating ports out of the first half of the ephemeral port range
is significantly faster, then allocating from the second half)

Without this change in a 32K ephemeral port space my sample program
(it just establishes and closes [::1]:ephemeral -> [::1]:server_port
connections in a tight loop) fails after 32765 connections in 24 seconds.
With it enabled 50000 connections only take 4.7 seconds.

This is particularly problematic for IPv6 where we only have one local
address and cannot play tricks with varying source IP from 127.0.0.0/8
pool.

Signed-off-by: Maciej Żenczykowski <maze@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Cc: Wei Wang <weiwan@google.com>
Change-Id: I0377961749979d0301b7b62871a32a4b34b654e1
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-06-04 17:13:35 -04:00
arch Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-06-03 09:31:58 -04:00
block
certs
crypto
Documentation net-tcp: extend tcp_tw_reuse sysctl to enable loopback only optimization 2018-06-04 17:13:35 -04:00
drivers qed: Add srq core support for RoCE and iWARP 2018-06-04 17:09:54 -04:00
firmware
fs rxrpc: Fix handling of call quietly cancelled out on server 2018-06-04 16:06:26 -04:00
include qed: Add srq core support for RoCE and iWARP 2018-06-04 17:09:54 -04:00
init
ipc
kernel Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-06-03 09:31:58 -04:00
lib
LICENSES
mm mm: fix the NULL mapping case in __isolate_lru_page() 2018-06-02 09:33:47 -07:00
net net-tcp: extend tcp_tw_reuse sysctl to enable loopback only optimization 2018-06-04 17:13:35 -04:00
samples
scripts
security Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-06-03 09:31:58 -04:00
sound
tools selftests: forwarding: mirror_vlan: Change test description 2018-06-04 10:08:45 -04:00
usr
virt
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.cocciconfig
.get_maintainer.ignore
.gitattributes
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COPYING
CREDITS
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MAINTAINERS MAINTAINERS: TCP gets its first maintainer 2018-06-04 10:32:00 -04:00
Makefile
README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.