WSL2-Linux-Kernel/init
Kirill A. Shutemov 0dea116876 cgroup: implement eventfd-based generic API for notifications
This patchset introduces eventfd-based API for notifications in cgroups
and implements memory notifications on top of it.

It uses statistics in memory controler to track memory usage.

Output of time(1) on building kernel on tmpfs:

Root cgroup before changes:
	make -j2  506.37 user 60.93s system 193% cpu 4:52.77 total
Non-root cgroup before changes:
	make -j2  507.14 user 62.66s system 193% cpu 4:54.74 total
Root cgroup after changes (0 thresholds):
	make -j2  507.13 user 62.20s system 193% cpu 4:53.55 total
Non-root cgroup after changes (0 thresholds):
	make -j2  507.70 user 64.20s system 193% cpu 4:55.70 total
Root cgroup after changes (1 thresholds, never crossed):
	make -j2  506.97 user 62.20s system 193% cpu 4:53.90 total
Non-root cgroup after changes (1 thresholds, never crossed):
	make -j2  507.55 user 64.08s system 193% cpu 4:55.63 total

This patch:

Introduce the write-only file "cgroup.event_control" in every cgroup.

To register new notification handler you need:
- create an eventfd;
- open a control file to be monitored. Callbacks register_event() and
  unregister_event() must be defined for the control file;
- write "<event_fd> <control_fd> <args>" to cgroup.event_control.
  Interpretation of args is defined by control file implementation;

eventfd will be woken up by control file implementation or when the
cgroup is removed.

To unregister notification handler just close eventfd.

If you need notification functionality for a control file you have to
implement callbacks register_event() and unregister_event() in the
struct cftype.

[kamezawa.hiroyu@jp.fujitsu.com: Kconfig fix]
Signed-off-by: Kirill A. Shutemov <kirill@shutemov.name>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Paul Menage <menage@google.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Dan Malek <dan@embeddedalley.com>
Cc: Vladislav Buzov <vbuzov@embeddedalley.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Alexander Shishkin <virtuoso@slind.org>
Cc: Davide Libenzi <davidel@xmailserver.org>
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-03-12 15:52:37 -08:00
..
Kconfig cgroup: implement eventfd-based generic API for notifications 2010-03-12 15:52:37 -08:00
Makefile kbuild: move compile.h to include/generated 2009-12-12 13:08:14 +01:00
calibrate.c timers, init: Limit the number of per cpu calibration bootup messages 2009-11-26 10:18:42 +01:00
do_mounts.c Driver Core: devtmpfs - kernel-maintained tmpfs-based /dev 2009-09-15 09:50:49 -07:00
do_mounts.h md: move lots of #include lines out of .h files and into .c 2009-03-31 14:33:13 +11:00
do_mounts_initrd.c init: Open /dev/console from rootfs 2010-03-03 14:56:07 -05:00
do_mounts_md.c md: move lots of #include lines out of .h files and into .c 2009-03-31 14:33:13 +11:00
do_mounts_rd.c init: make initrd/initramfs decompression failure a KERN_EMERG event 2009-01-14 11:28:35 -08:00
initramfs.c init/initramfs.c: fix "symbol shadows an earlier one" noise 2010-03-06 11:26:29 -08:00
main.c init/main.c: make setup_max_cpus static for !SMP 2010-03-06 11:26:32 -08:00
noinitramfs.c [PATCH] disable init/initramfs.c 2007-02-11 10:51:25 -08:00
version.c kbuild: move utsrelease.h to include/generated 2009-12-12 13:08:15 +01:00