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Filename Latest commit message Latest commit date
Eric Dumazet 79134e6ce2 net: do not create fallback tunnels for non-default namespaces
fallback tunnels (like tunl0, gre0, gretap0, erspan0, sit0,
ip6tnl0, ip6gre0) are automatically created when the corresponding
module is loaded.

These tunnels are also automatically created when a new network
namespace is created, at a great cost.

In many cases, netns are used for isolation purposes, and these
extra network devices are a waste of resources. We are using
thousands of netns per host, and hit the netns creation/delete
bottleneck a lot. (Many thanks to Kirill for recent work on this)

Add a new sysctl so that we can opt-out from this automatic creation.

Note that these tunnels are still created for the initial namespace,
to be the least intrusive for typical setups.

Tested:
lpk43:~# cat add_del_unshare.sh
for i in `seq 1 40`
do
 (for j in `seq 1 100` ; do  unshare -n /bin/true >/dev/null ; done) &
done
wait

lpk43:~# echo 0 >/proc/sys/net/core/fb_tunnels_only_for_init_net
lpk43:~# time ./add_del_unshare.sh

real	0m37.521s
user	0m0.886s
sys	7m7.084s
lpk43:~# echo 1 >/proc/sys/net/core/fb_tunnels_only_for_init_net
lpk43:~# time ./add_del_unshare.sh

real	0m4.761s
user	0m0.851s
sys	1m8.343s
lpk43:~#

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-03-09 11:23:11 -05:00
arch Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-03-06 01:20:46 -05:00
block for-linus-20180302 2018-03-02 09:35:36 -08:00
certs
crypto
Documentation net: do not create fallback tunnels for non-default namespaces 2018-03-09 11:23:11 -05:00
drivers net: dsa: mv88e6xxx: Fix irq free'ing 2018-03-09 11:20:59 -05:00
firmware
fs Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-03-06 01:20:46 -05:00
include net: do not create fallback tunnels for non-default namespaces 2018-03-09 11:23:11 -05:00
init
ipc
kernel Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-03-06 01:20:46 -05:00
lib Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-03-06 01:20:46 -05:00
LICENSES
mm
net net: do not create fallback tunnels for non-default namespaces 2018-03-09 11:23:11 -05:00
samples Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-03-06 01:20:46 -05:00
scripts Kbuild fixes for v4.16 2018-03-03 10:37:01 -08:00
security
sound
tools tools: tc-testing: Can pause just before post-suite 2018-03-09 11:22:18 -05:00
usr
virt
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS lan743x: Update MAINTAINERS to include lan743x driver 2018-03-07 11:44:42 -05:00
Makefile Linux 4.16-rc4 2018-03-04 14:54:11 -08:00
README

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

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

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.