No description
  • C 98.2%
  • Assembly 1%
  • Makefile 0.3%
  • Shell 0.2%
  • Python 0.1%
Find a file
Repository files (latest commit first)
Filename Latest commit message Latest commit date
David S. Miller bedf3b3320 Merge branch 'net-mitigate-retpoline-overhead'
Paolo Abeni says:

====================
net: mitigate retpoline overhead

The spectre v2 counter-measures, aka retpolines, are a source of measurable
overhead[1]. We can partially address that when the function pointer refers to
a builtin symbol resorting to a list of tests vs well-known builtin function and
direct calls.

Experimental results show that replacing a single indirect call via
retpoline with several branches and a direct call gives performance gains
even when multiple branches are added - 5 or more, as reported in [2].

This may lead to some uglification around the indirect calls. In netconf 2018
Eric Dumazet described a technique to hide the most relevant part of the needed
boilerplate with some macro help.

This series is a [re-]implementation of such idea, exposing the introduced
helpers in a new header file. They are later leveraged to avoid the indirect
call overhead in the GRO path, when possible.

Overall this gives > 10% performance improvement for UDP GRO benchmark and
smaller but measurable for TCP syn flood.

The added infra can be used in follow-up patches to cope with retpoline overhead
in other points of the networking stack (e.g. at the qdisc layer) and possibly
even in other subsystems.

v2  -> v3:
 - fix build error with CONFIG_IPV6=m

v1  -> v2:
 - list explicitly the builtin function names in INDIRECT_CALL_*(),
   as suggested by Ed Cree
 - expand the recipients list

rfc -> v1:
 - use branch prediction hints, as suggested by Eric

[1] http://vger.kernel.org/netconf2018_files/PaoloAbeni_netconf2018.pdf
[2] https://linuxplumbersconf.org/event/2/contributions/99/attachments/98/117/lpc18_paper_af_xdp_perf-v2.pdf
====================

Signed-off-by: David S. Miller <davem@davemloft.net>
2018-12-15 13:23:03 -08:00
arch Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2018-12-10 18:00:43 -08:00
block blk-mq: punt failed direct issue to dispatch list 2018-12-07 08:16:11 -07:00
certs
crypto crypto: user - Disable statistics interface 2018-12-07 13:56:08 +08:00
Documentation dt-bindings: net: ravb: Add support for r8a774c0 SoC 2018-12-15 13:04:55 -08:00
drivers net: socionext: remove mmio reads on Tx 2018-12-15 13:15:19 -08:00
firmware
fs a fix for smb3 direct i/o, a fix for CIFS DFS for stable and a minor cifs Kconfig fix 2018-12-09 10:15:13 -08:00
include net: use indirect call wrappers at GRO transport layer 2018-12-15 13:23:02 -08:00
init initramfs: clean old path before creating a hardlink 2018-11-30 14:56:14 -08:00
ipc
kernel Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2018-12-10 18:00:43 -08:00
lib Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-12-09 21:43:31 -08:00
LICENSES
mm dax fixes 4.20-rc6 2018-12-09 09:54:04 -08:00
net udp: use indirect call wrappers for GRO socket lookup 2018-12-15 13:23:02 -08:00
samples samples: bpf: fix: seg fault with NULL pointer arg 2018-12-03 23:58:03 +01:00
scripts Fixes for stackleak 2018-12-07 13:13:07 -08:00
security selinux/stable-4.20 PR 20181129 2018-11-29 10:15:06 -08:00
sound ALSA: hda/realtek: Fix mic issue on Acer AIO Veriton Z4860G/Z6860G 2018-12-05 16:39:59 +01:00
tools selftests: net: test that listening sockets match on address properly 2018-12-14 15:55:20 -08:00
usr
virt
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS MAINTAINERS: change Sparse's maintainer 2018-11-25 09:17:43 -08:00
Kbuild
Kconfig
MAINTAINERS Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-12-09 21:43:31 -08:00
Makefile Linux 4.20-rc6 2018-12-09 15:31:00 -08:00
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.

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.