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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>		17 years ago
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appldata	Merge branch 'generic-ipi' into generic-ipi-for-linus	17 years ago
boot	[PATCH] use ${CROSS_COMPILE}installkernel in arch/*/boot/install.sh	20 years ago
crypto	Merge branch 'bkl-removal' of git://git.lwn.net/linux-2.6	17 years ago
hypfs	vfs: Use const for kernel parser table	17 years ago
include/asm	container freezer: add TIF_FREEZE flag to all architectures	17 years ago
kernel	compat: generic compat get/settimeofday	17 years ago
kvm	KVM: s390: Make facility bits future-proof	17 years ago
lib	[S390] Move private simple udelay function to arch/s390/lib/delay.c.	17 years ago
math-emu	[S390] remove -traditional	17 years ago
mm	mm: cleanup to make remove_memory() arch-neutral	17 years ago
oprofile	Combine instrumentation menus in kernel/Kconfig.instrumentation	18 years ago
Kconfig	container freezer: implement freezer cgroup subsystem	17 years ago
Kconfig.debug	[S390] DEBUG_PAGEALLOC support for s390.	17 years ago
Makefile	KVM: s390: arch backend for the kvm kernel module	17 years ago
defconfig	[S390] Update default configuration.	17 years ago