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Tejun Heo a74ebf047e cgroup, rstat: Don't flush subtree root unless necessary
[ Upstream commit b4ff1b44bc ]

cgroup_rstat_cpu_pop_updated() is used to traverse the updated cgroups
on flush.  While it was only visiting updated ones in the subtree, it
was visiting @root unconditionally.  We can easily check whether @root
is updated or not by looking at its ->updated_next just as with the
cgroups in the subtree.

* Remove the unnecessary cgroup_parent() test.  The system root cgroup
  is never updated and thus its ->updated_next is always NULL.  No
  need to test whether cgroup_parent() exists in addition to
  ->updated_next.

* Terminate traverse if ->updated_next is NULL.  This can only happen
  for subtree @root and there's no reason to visit it if it's not
  marked updated.

This reduces cpu consumption when reading a lot of rstat backed files.
In a micro benchmark reading stat from ~1600 cgroups, the sys time was
lowered by >40%.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2019-04-05 22:33:06 +02:00
arch powerpc/hugetlb: Handle mmap_min_addr correctly in get_unmapped_area callback 2019-04-05 22:33:02 +02:00
block blk-mq: insert rq with DONTPREP to hctx dispatch list when requeue 2019-03-23 20:09:45 +01:00
certs export.h: remove VMLINUX_SYMBOL() and VMLINUX_SYMBOL_STR() 2018-08-22 23:21:44 +09:00
crypto crypto: testmgr - skip crc32c context test for ahash algorithms 2019-03-23 20:09:55 +01:00
Documentation KVM: Reject device ioctls from processes other than the VM's creator 2019-04-03 06:26:29 +02:00
drivers HID: intel-ish-hid: avoid binding wrong ishtp_cl_device 2019-04-05 22:33:06 +02:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs vfs: fix preadv64v2 and pwritev64v2 compat syscalls with offset == -1 2019-04-05 22:33:06 +02:00
include scsi: fcoe: make use of fip_mode enum complete 2019-04-05 22:33:04 +02:00
init Revert "mm: use early_pfn_to_nid in page_ext_init" 2019-03-23 20:09:46 +01:00
ipc ipc/shm.c: use ERR_CAST() for shm_lock() error return 2018-10-05 16:32:04 -07:00
kernel cgroup, rstat: Don't flush subtree root unless necessary 2019-04-05 22:33:06 +02:00
lib rhashtable: Still do rehash when we get EEXIST 2019-04-03 06:26:17 +02:00
LICENSES LICENSES: Remove CC-BY-SA-4.0 license text 2018-10-18 11:28:50 +02:00
mm page_poison: play nicely with KASAN 2019-04-05 22:32:59 +02:00
net netfilter: conntrack: tcp: only close if RST matches exact sequence 2019-04-05 22:33:00 +02:00
samples samples: mei: use /dev/mei0 instead of /dev/mei 2019-02-15 08:10:11 +01:00
scripts kbuild: modversions: Fix relative CRC byte order interpretation 2019-04-03 06:26:23 +02:00
security security/selinux: fix SECURITY_LSM_NATIVE_LABELS on reused superblock 2019-03-23 20:10:06 +01:00
sound SoC: imx-sgtl5000: add missing put_device() 2019-04-05 22:33:05 +02:00
tools perf report: Don't shadow inlined symbol with different addr range 2019-04-05 22:33:05 +02:00
usr initramfs: move gen_initramfs_list.sh from scripts/ to usr/ 2018-08-22 23:21:44 +09:00
virt KVM: Reject device ioctls from processes other than the VM's creator 2019-04-03 06:26:29 +02:00
.clang-format clang-format: Set IndentWrappedFunctionNames false 2018-08-01 18:38:51 +02:00
.cocciconfig
.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 libnvdimm-for-4.19_misc 2018-08-25 18:13:10 -07:00
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 MAINTAINERS: Add Sasha as a stable branch maintainer 2018-12-01 09:37:25 +01:00
Makefile kbuild: invoke syncconfig if include/config/auto.conf.cmd is missing 2019-04-05 22:33:01 +02:00
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.