Messages in this thread | | | Date | Fri, 14 Oct 2011 17:38:47 +0200 | From | Frederic Weisbecker <> | Subject | Re: A Plumber’ s Wish List for Linux |
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On Wed, Oct 12, 2011 at 10:16:41PM +0400, Cyrill Gorcunov wrote: > On Wed, Oct 12, 2011 at 10:40:14AM -0700, Tejun Heo wrote: > ... > > > > In general, I think making freezer work nicely with the rest of the > > system is a good idea and have been working towards that direction. > > Allowing a frozen task to be killed is not only handy for use cases > > like above but also makes solving freezer involved deadlocks much less > > likely and easier to solve. Another that I have in mind is allowing > > ptrace from unfrozen task to a frozen task. This can be helpful in > > general debugging (currently attaching to multi-threaded, violently > > cloning process is quite cumbersome) and userland checkpointing. > > Yeah, being able to ptrace a frozen cgroup would be great for us. > We stick with signals start/stop cycle at moment but the final target > is the cgroups and freezer of course. (btw while were poking freezer > code I noticed that there is no shortcut to move all tasks in cgroup > into the root cgroup, so I guess say "echo -1 > tasks" might be a good > addition to move all tasks from some particular cgroup to the root > by single action).
Well, wouldn't it be better to pull that complexity to userspace? After all, moving tasks from a cgroup to another is not a performance critical operation so that probably doesn't need to be all handled by the kernel.
If one worries about concurrent clone/fork while moving tasks, then freezing the cgroup and moving its tasks away from userspace could be enough?
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