Matt Helsley wrote: > On Fri, Oct 22, 2010 at 04:11:41PM +0800, Li Zefan wrote: >> To make it bindable, we need to thaw all processes when unbinding >> the freezer subsystem from a cgroup hierarchy. >> >> Signed-off-by: Li Zefan <lizf@xxxxxxxxxxxxxx> > > Based on experience using cgroups and questions we've fielded in the > past on IRC I'd say users will really appreciate this. > > We're planning to use the freezer in checkpoint/restart. Since > checkpoint requires the tasks to remain frozen for the duration of > the syscall we add a kernel-internal freezer subsystem interface > which prevents the cgroup from thawing. So we'll need some way to > "block" unbinding for that as well. > How about, we allow unbinding only when all the cgroups' state is THAWED ? > Perhaps the bind op should be able to return an error when > unbind == true? Although that raises the question of what to do if > only one of multiple unbinds fails.. > > Alternately you could split the bind/unbind op function pointers > and get rid of the boolean argument. Then just don't fill in the > freezer's unbind op and refuse to unbind subsystems that lack > the unbind op. That seems a bit cleaner for now at least. > We can use bindable:1 along with a callback can_bind(). For some subsystems, we just set bindable to true. For freezer subsystem, we set it to true and provide freezer_can_bind(), and return true only if no cgroup's state is FROZEN. _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/containers
