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Nicholas Piggin 1e1c15839d fs/epoll: use a per-cpu counter for user's watches count
This counter tracks the number of watches a user has, to compare against
the 'max_user_watches' limit. This causes a scalability bottleneck on
SPECjbb2015 on large systems as there is only one user. Changing to a
per-cpu counter increases throughput of the benchmark by about 30% on a
16-socket, > 1000 thread system.

[rdunlap@infradead.org: fix build errors in kernel/user.c when CONFIG_EPOLL=n]
[npiggin@gmail.com: move ifdefs into wrapper functions, slightly improve panic message]
  Link: https://lkml.kernel.org/r/1628051945.fens3r99ox.astroid@bobo.none
[akpm@linux-foundation.org: tweak user_epoll_alloc(), per Guenter]
  Link: https://lkml.kernel.org/r/20210804191421.GA1900577@roeck-us.net

Link: https://lkml.kernel.org/r/20210802032013.2751916-1-npiggin@gmail.com
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reported-by: Anton Blanchard <anton@ozlabs.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-08 11:50:27 -07:00
arch arch: Kconfig: fix spelling mistake "seperate" -> "separate" 2021-09-08 11:50:25 -07:00
block block-5.14-2021-08-27 2021-08-27 16:08:29 -07:00
certs Kbuild updates for v5.13 (2nd) 2021-05-08 10:00:11 -07:00
crypto crypto: drbg - select SHA512 2021-07-16 15:49:31 +08:00
Documentation Documentation/llvm: update IRC location 2021-09-08 11:50:26 -07:00
drivers phy/drivers/stm32: use HZ macros 2021-09-08 11:50:26 -07:00
fs fs/epoll: use a per-cpu counter for user's watches count 2021-09-08 11:50:27 -07:00
include fs/epoll: use a per-cpu counter for user's watches count 2021-09-08 11:50:27 -07:00
init init: Suppress wrong warning for bootconfig cmdline parameter 2021-08-12 13:35:57 -04:00
ipc Merge branch 'akpm' (patches from Andrew) 2021-07-02 12:08:10 -07:00
kernel fs/epoll: use a per-cpu counter for user's watches count 2021-09-08 11:50:27 -07:00
lib lib/iov_iter.c: fix kernel-doc warnings 2021-09-08 11:50:26 -07:00
LICENSES LICENSES/dual/CC-BY-4.0: Git rid of "smart quotes" 2021-07-15 06:31:24 -06:00
mm percpu: remove export of pcpu_base_addr 2021-09-08 11:50:25 -07:00
net This is a one-liner fix for a serious bug that can cause the server to 2021-08-26 13:26:40 -07:00
samples Networking fixes for 5.14-rc2, including fixes from bpf and netfilter. 2021-07-14 09:24:32 -07:00
scripts checkpatch: improve GIT_COMMIT_ID test 2021-09-08 11:50:27 -07:00
security bpf: Add lockdown check for probe_write_user helper 2021-08-10 10:10:10 +02:00
sound another sound-fixes for 5.14-rc7 2021-08-20 12:31:10 -07:00
tools tools: rename bitmap_alloc() to bitmap_zalloc() 2021-09-08 11:50:27 -07:00
usr .gitignore: prefix local generated files with a slash 2021-05-02 00:43:35 +09:00
virt KVM: Do not leak memory for duplicate debugfs directories 2021-08-04 06:02:03 -04:00
.clang-format clang-format: Update with the latest for_each macro list 2021-05-12 23:32:39 +02:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap m68k updates for v5.14 2021-06-28 14:01:03 -07:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: move Murali Karicheri to credits 2021-04-29 15:47:30 -07:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS MAINTAINERS: update ClangBuiltLinux mailing list 2021-09-08 11:50:26 -07:00
Makefile Linux 5.14 2021-08-29 15:04:50 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.