This patchset is a prototype using the container infrastructure and
the swsusp freezer to freeze a group of tasks. I've merely taken Cedric's
patches, forward-ported them to 2.6.25-rc8-mm1 and done a small amount of
testing.
2 files are defined by the freezer subsystem in the container
filesystem :
* "freezer.freeze"
writing 1 will freeze all tasks and 0 unfreeze
reading will return the status of the freezer
* "freezer.kill"
writing <n> will send signal number <n> to all tasks
* Usage :
# mkdir /containers/freezer
# mount -t container -ofreezer freezer /containers/freezer
# mkdir /containers/freezer/0
# echo $some_pid > /containers/freezer/0/tasks
to get status of the freezer subsystem :
# cat /containers/freezer/0/freezer.freeze
RUNNING
to freeze all tasks in the container :
# echo 1 > /containers/freezer/0/freezer.freeze
# cat /containers/freezer/0/freezer.freeze
FREEZING
# cat /containers/freezer/0/freezer.freeze
FROZEN
to unfreeze all tasks in the container :
# echo 1 > /containers/freezer/0/freezer.freeze
# cat /containers/freezer/0/freezer.freeze
RUNNING
to kill all tasks in the container :
# echo 9 > /containers/freezer/0/freezer.kill
* Caveats:
- the FROZEN status is calculated and changed when the container
file "freezer.freeze" is read.
- frozen containers will be unfrozen when a system is resumed after
a suspend. This is addressed by the last patch.
* Series
Applies to 2.6.25-rc8-mm1
The first patches make the freezer available to all architectures
before implementing the freezer subsystem.
[PATCH 1/4] Add TIF_FREEZE flag to all architectures
[PATCH 2/4] Make refrigerator always available
[PATCH 3/4] Implement freezer cgroup subsystem
[PATCH 4/4] Skip frozen cgroups during power management resume
Each patch compiles, boots, and survives basic LTP containers and controllers
tests.
Comments are welcome.
Cheers,
-Matt Helsley
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