RFC Container Freezer: Reuse Suspend Freezer
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- v1 RFC Latest5 patches 49 repliesIn review
v2 (roughly patches 3 and 5) from the cover letter
Moved the "kill" file into a separate cgroup subsystem (signal) and
it's own patch.
Changed the name of the file from freezer.freeze to freezer.state. Switched from taking 1 and 0 as input to the strings "FROZEN" and
"RUNNING", respectively. This helps keep the interface human-usable if/when we need to more states.
Checked that stopped or interrupted is "frozen enough"
Since try_to_freeze() is called upon wakeup of these tasks this should be fine. This idea comes from recent changes to the freezer.
Checked that if (task == current) whilst freezing cgroup we're ok Fixed bug where -EBUSY would always be returned when freezing Added code to handle userspace retries for any remaining -EBUSY
Patches in v1 No applies recorded yet
| # | Subject and files | Size | Replies | Applied |
|---|---|---|---|---|
| 1/5 | Container Freezer: Add TIF_FREEZE flag to all architecturesinclude/ include/ include/ +10 more | +25 | 0 replies | |
| 1/5 | Container Freezer: Add TIF_FREEZE flag to all architecturesinclude/ include/ include/ +10 more | +25 | 3 replies | |
| 2/5 | Container Freezer: Make refrigerator always availableinclude/ kernel/ kernel/ +1 more | +133 | 0 replies | |
| 2/5 | Container Freezer: Make refrigerator always availableinclude/ kernel/ kernel/ +1 more | +133 | 15 replies | |
| 3/5 | Container Freezer: Implement freezer cgroup subsysteminclude/ include/ init/ +3 more | +356 | 0 replies | |
| 3/5 | Container Freezer: Implement freezer cgroup subsysteminclude/ include/ init/ +3 more | +356 | 15 replies | |
| 4/5 | Container Freezer: Skip frozen cgroups during power management resumekernel/ | +4 | 0 replies | |
| 4/5 | Container Freezer: Skip frozen cgroups during power management resumekernel/ | +4 | 0 replies | |
| 5/5 | Add a Signal Control Group Subsysteminclude/ include/ init/ +2 more | +170 | 0 replies | |
| 5/5 | Add a Signal Control Group Subsysteminclude/ include/ init/ +2 more | +170 | 19 replies |
Reviews trailers per patch
None of the 10 patches has a Reviewed-by or Acked-by.
| Patch | Matt Helsley |
|---|---|
| Series | T-b T-b T-b T-b |
| 1/5 | T-b T-b |
| 1/5 | T-b T-b |
| 2/5 | T-b T-b |
| 2/5 | T-b T-b |
| 3/5 | T-b T-b |
| 3/5 | T-b T-b |
| 4/5 | T-b T-b |
| 4/5 | T-b T-b |
| 5/5 | |
| 5/5 |
Trailers given in replies are filled; those carried in the patches from earlier versions are outlined with dashes.
Cover letter [RFC][PATCH 0/5] Container Freezer: Reuse Suspend Freezer
This patchset reuses 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-mm1 and tested the expected common cases.
Changes since v1:
v2 (roughly patches 3 and 5):
Moved the "kill" file into a separate cgroup subsystem (signal) and
it's own patch.
Changed the name of the file from freezer.freeze to freezer.state. Switched from taking 1 and 0 as input to the strings "FROZEN" and
"RUNNING", respectively. This helps keep the interface human-usable if/when we need to more states.
Checked that stopped or interrupted is "frozen enough"
Since try_to_freeze() is called upon wakeup of these tasks this should be fine. This idea comes from recent changes to the freezer.
Checked that if (task == current) whilst freezing cgroup we're ok Fixed bug where -EBUSY would always be returned when freezing Added code to handle userspace retries for any remaining -EBUSY
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,signal 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.state RUNNING
to freeze all tasks in the container :
# echo FROZEN > /containers/freezer/0/freezer.state # cat /containers/freezer/0/freezer.state FREEZING # cat /containers/freezer/0/freezer.state FROZEN
to unfreeze all tasks in the container :
# echo RUNNING > /containers/freezer/0/freezer.state # cat /containers/freezer/0/freezer.state RUNNING
to kill all tasks in the container :
# echo 9 > /containers/freezer/0/signal.kill
* Caveats:
- The cgroup moves into the FROZEN state once all tasks in the cgroup are frozen. This is calculated and changed when the container file "freezer.state" is read or written.
- Frozen containers will be unfrozen when a system is resumed after a suspend. This is addressed by a subsequent patch.
* Series
Applies to 2.6.25-mm1
The first patches make the freezer available to all architectures before implementing the freezer cgroup subsystem.
[RFC PATCH 1/5] Add TIF_FREEZE flag to all architectures [RFC PATCH 2/5] Make refrigerator always available
[RFC PATCH 3/5] Implement freezer cgroup subsystem
[RFC PATCH 4/5] Skip frozen cgroups during power management resume [RFC PATCH 5/5] Implement signal cgroup subsytem
Comments are welcome. I'm planning to finish up testing with ptrace'd and vforking processes and then, if it still seems appropriate, resubmit as a non-RFC series next.
Cheers,
-Matt Helsley