Matt Helsley dc52ddc0e6 container freezer: implement freezer cgroup subsystem ... This patch implements a new freezer subsystem in the control groups framework. It provides a way to stop and resume execution of all tasks in a cgroup by writing in the cgroup filesystem. The freezer subsystem in the container filesystem defines a file named freezer.state. Writing "FROZEN" to the state file will freeze all tasks in the cgroup. Subsequently writing "RUNNING" will unfreeze the tasks in the cgroup. Reading will return the current state. * Examples of usage : # mkdir /containers/freezer # mount -t cgroup -ofreezer freezer /containers # mkdir /containers/0 # echo $some_pid > /containers/0/tasks to get status of the freezer subsystem : # cat /containers/0/freezer.state RUNNING to freeze all tasks in the container : # echo FROZEN > /containers/0/freezer.state # cat /containers/0/freezer.state FREEZING # cat /containers/0/freezer.state FROZEN to unfreeze all tasks in the container : # echo RUNNING > /containers/0/freezer.state # cat /containers/0/freezer.state RUNNING This is the basic mechanism which should do the right thing for user space task in a simple scenario. It's important to note that freezing can be incomplete. In that case we return EBUSY. This means that some tasks in the cgroup are busy doing something that prevents us from completely freezing the cgroup at this time. After EBUSY, the cgroup will remain partially frozen -- reflected by freezer.state reporting "FREEZING" when read. The state will remain "FREEZING" until one of these things happens: 1) Userspace cancels the freezing operation by writing "RUNNING" to the freezer.state file 2) Userspace retries the freezing operation by writing "FROZEN" to the freezer.state file (writing "FREEZING" is not legal and returns EIO) 3) The tasks that blocked the cgroup from entering the "FROZEN" state disappear from the cgroup's set of tasks. [akpm@linux-foundation.org: coding-style fixes] [akpm@linux-foundation.org: export thaw_process] Signed-off-by: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Matt Helsley <matthltc@us.ibm.com> Acked-by: Serge E. Hallyn <serue@us.ibm.com> Tested-by: Matt Helsley <matthltc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>		2008-10-20 08:52:34 -07:00
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amiga	m68k: Modular Amiga keyboard needs key_maps	2008-10-14 10:23:26 -07:00
apollo
atari	m68k: Remove the broken Hades support	2008-10-14 10:23:27 -07:00
bvme6000	m68k: use bcd2bin/bin2bcd	2008-10-14 10:23:26 -07:00
configs	m68k: Update defconfigs for 2.6.27-rc6	2008-09-10 14:15:29 -07:00
fpsp040	Stringify support commas	2008-07-20 17:24:38 -07:00
hp300	m68k: kill arch/m68k/hp300/ksyms.c	2008-02-05 09:44:23 -08:00
ifpsp060	Stringify support commas	2008-07-20 17:24:38 -07:00
kernel	m68k: init_irq_proc depends on CONFIG_PROC_FS	2008-10-14 10:23:27 -07:00
lib	Stringify support commas	2008-07-20 17:24:38 -07:00
mac	remove unneeded #include <linux/ide.h>'s	2008-08-05 18:17:00 +02:00
math-emu	Stringify support commas	2008-07-20 17:24:38 -07:00
mm	arch/m68k/mm/kmap.c: introduce missing kfree	2008-10-14 10:23:27 -07:00
mvme16x	m68k: use bcd2bin/bin2bcd	2008-10-14 10:23:26 -07:00
mvme147
q40	m68k: use bcd2bin/bin2bcd	2008-10-14 10:23:26 -07:00
sun3	m68k/sun3/: possible cleanups	2008-07-20 17:24:39 -07:00
sun3x	m68k: use bcd2bin/bin2bcd	2008-10-14 10:23:26 -07:00
tools/amiga	Convert files to UTF-8 and some cleanups	2007-10-19 23:21:04 +02:00
Kconfig	container freezer: implement freezer cgroup subsystem	2008-10-20 08:52:34 -07:00
Kconfig.debug
Makefile	m68k: make multi_defconfig the default defconfig	2008-07-20 17:24:38 -07:00