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Shakeel Butt 8de7ecc648 memcg: reduce memcg tree traversals for stats collection
Currently cgroup-v1's memcg_stat_show traverses the memcg tree ~17 times
to collect the stats while cgroup-v2's memory_stat_show traverses the
memcg tree thrice.  On a large machine, a couple thousand memcgs is very
normal and if the churn is high and memcgs stick around during to several
reasons, tens of thousands of nodes in memcg tree can exist.  This patch
has refactored and shared the stat collection code between cgroup-v1 and
cgroup-v2 and has reduced the tree traversal to just one.

I ran a simple benchmark which reads the root_mem_cgroup's stat file
1000 times in the presense of 2500 memcgs on cgroup-v1. The results are:

Without the patch:
$ time ./read-root-stat-1000-times

real    0m1.663s
user    0m0.000s
sys     0m1.660s

With the patch:
$ time ./read-root-stat-1000-times

real    0m0.468s
user    0m0.000s
sys     0m0.467s

Link: http://lkml.kernel.org/r/20180724224635.143944-1-shakeelb@google.com
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Bruce Merry <bmerry@ska.ac.za>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-08-22 10:52:44 -07:00
arch mm: zero out the vma in vma_init() 2018-08-22 10:52:44 -07:00
block for-4.19/block-20180812 2018-08-14 10:23:25 -07:00
certs Replace magic for trusting the secondary keyring with #define 2018-08-16 09:57:20 -07:00
crypto DMAengine updates for v4.19-rc1 2018-08-18 15:55:59 -07:00
Documentation mm: clarify CONFIG_PAGE_POISONING and usage 2018-08-22 10:52:44 -07:00
drivers mm, oom: distinguish blockable mode for mmu notifiers 2018-08-22 10:52:44 -07:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs mm: zero out the vma in vma_init() 2018-08-22 10:52:44 -07:00
include mm: zero out the vma in vma_init() 2018-08-22 10:52:44 -07:00
init Updates for v4.19: 2018-08-20 18:32:00 -07:00
ipc Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2018-08-15 15:04:25 -07:00
kernel mm: zero out the vma in vma_init() 2018-08-22 10:52:44 -07:00
lib Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-08-19 11:51:45 -07:00
LICENSES LICENSES: Add Linux-OpenIB license text 2018-04-27 16:41:53 -06:00
mm memcg: reduce memcg tree traversals for stats collection 2018-08-22 10:52:44 -07:00
net The main things are support for cephx v2 authentication protocol and 2018-08-20 18:26:55 -07:00
samples samples/bpf: all XDP samples should unload xdp/bpf prog on SIGTERM 2018-08-16 21:55:32 +02:00
scripts Updates for v4.19: 2018-08-20 18:32:00 -07:00
security Merge branch 'next-integrity' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2018-08-15 22:54:12 -07:00
sound DMAengine updates for v4.19-rc1 2018-08-18 15:55:59 -07:00
tools linux-kselftest-4.19-rc1 2018-08-20 19:02:17 -07:00
usr kbuild: rename built-in.o to built-in.a 2018-03-26 02:01:19 +09:00
virt mm, oom: distinguish blockable mode for mmu notifiers 2018-08-22 10:52:44 -07:00
.clang-format clang-format: Set IndentWrappedFunctionNames false 2018-08-01 18:38:51 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore Kbuild updates for v4.17 (2nd) 2018-04-15 17:21:30 -07:00
.mailmap Merge branch 'linus/master' into rdma.git for-next 2018-08-16 14:21:29 -06:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS 9p: remove Ron Minnich from MAINTAINERS 2018-08-17 16:20:26 -07:00
Kbuild Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
Kconfig kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt 2018-08-02 08:06:55 +09:00
MAINTAINERS - New Drivers 2018-08-20 15:38:44 -07:00
Makefile Updates for v4.19: 2018-08-20 18:32:00 -07:00
README Docs: Added a pointer to the formatted docs to README 2018-03-21 09:02:53 -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.
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.