linux/arch/mips
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
..
alchemy MIPS: Alchemy: rename directory 2008-10-11 16:18:50 +01:00
basler/excite [MIPS] kgdb: Remove existing implementation 2008-07-30 21:54:42 +01:00
bcm47xx MIPS: WGT634U: Add reset button support 2008-10-15 12:46:51 +01:00
boot [MIPS] checkfiles: Fix "need space after that ','" errors. 2007-10-11 23:46:15 +01:00
cobalt [MIPS] Cobalt: Fix I/O port resource range 2008-07-20 14:38:20 +01:00
configs [MIPS] Cobalt: update defconfig 2008-07-30 21:54:43 +01:00
dec [MIPS] DS1287: Add clockevent driver 2008-04-28 17:14:32 +01:00
emma2rh MIPS: Kill unused <asm/debug.h> inclusions 2008-10-15 12:46:52 +01:00
fw [MIPS] Remove mips_machtype from ARC based machines 2008-07-15 18:44:38 +01:00
gt64120/wrppmc [MIPS] remove wrppmc_machine_power_off() 2008-07-15 18:44:36 +01:00
include/asm [PATCH] remove unused ibcs2/PER_SVR4 in SET_PERSONALITY 2008-10-16 15:40:05 +02:00
jazz [MIPS] Jazz: Fix build error by header file inclusion weeding. 2008-08-26 09:10:20 +01:00
kernel Merge git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core-2.6 2008-10-16 12:40:26 -07:00
lasat sysctl: simplify ->strategy 2008-10-16 11:21:47 -07:00
lemote/lm2e [MIPS] Fulong: don't reinitialize pci_probe_only to it's default value. 2008-01-29 10:14:59 +00:00
lib MIPS: IP checksums: Optimize adjust of sum on buffers of odd alignment. 2008-10-11 16:18:53 +01:00
math-emu [MIPS] Fix missing prototypes in asm/fpu.h 2008-07-20 14:38:17 +01:00
mipssim [MIPS] Remove TLB sanitation code 2008-04-28 17:14:25 +01:00
mm [MIPS] TX39xx: Add missing local_flush_icache_range initialization 2008-09-05 21:24:12 +01:00
mti-malta [MIPS] SMTC: Fix SMTC dyntick support. 2008-10-03 17:58:58 +01:00
nxp/pnx8550 [MIPS] kgdb: Remove existing implementation 2008-07-30 21:54:42 +01:00
oprofile generic-ipi: more merge fallout 2008-07-15 22:08:52 +02:00
pci MIPS: Kill unused <asm/debug.h> inclusions 2008-10-15 12:46:52 +01:00
pmc-sierra MIPS: PMC MSP71XX gpio drivers 2008-10-11 16:18:41 +01:00
rb532 MIPS: Kill unused <asm/debug.h> inclusions 2008-10-15 12:46:52 +01:00
sgi-ip22 MIPS: IP22/28: Switch over to RTC class driver 2008-10-15 12:46:51 +01:00
sgi-ip27 MIPS: IP27: Switch over to RTC class driver 2008-10-15 12:46:51 +01:00
sgi-ip32 MIPS: IP32: Add platform device for CMOS RTC; remove dead code 2008-10-15 12:46:52 +01:00
sibyte device create: misc: convert device_create_drvdata to device_create 2008-10-16 09:24:43 -07:00
sni [MIPS] Remove obsolete isa_slot_offset 2008-07-15 18:44:29 +01:00
txx9 MIPS: TXx9: Add TX4939 ATA support (v2) 2008-10-11 16:18:54 +01:00
vr41xx [MIPS] VR41xx: unsigned irq cannot be negative 2008-09-16 11:04:30 +02:00
Kconfig container freezer: implement freezer cgroup subsystem 2008-10-20 08:52:34 -07:00
Kconfig.debug [MIPS] kgdb: Remove existing implementation 2008-07-30 21:54:42 +01:00
Makefile MIPS: Move headfiles to new location below arch/mips/include 2008-10-11 16:18:52 +01:00