Messages in this thread | | | Date | Mon, 10 Mar 2014 14:17:21 +0000 | From | Glyn Normington <> | Subject | Re: [PATCH] control groups: documentation improvements |
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Hi Tejun
Thanks for your quick reply. Responses inline.
Regards, Glyn
On 10/03/2014 14:07, Tejun Heo wrote: > Hello, Glyn. > > On Mon, Mar 10, 2014 at 11:39:28AM +0000, Glyn Normington wrote: >> Clarify that each hierarchy must be associated with at least one >> subsystem. > Hmmm... but named hierarchies can exist without any controllers > attached to them. Then we missed how to create a hierarchy with no associated subsystems. The only way I can think of is to use mount, specify no subsystems on -o (which defaults to all the subsystems defined in the kernel), and run it in a kernel with no subsystems defined (which seems unlikely these days).
Is that what you had in mind or is there some other way of creating a hierarchy with no subsystems attached? > >> Clarify that subsystems may be attached to multiple hierarchies, >> although this isn't very useful, and explain what happens. > And a subsystem may only be attached to a single hierarchy. Perhaps that's what should happen, but the following experiment demonstrates a subsystem being attached to two hierarchies:
$ pwd /home/vagrant $ mkdir mem1 $ mkdir mem2 $ sudo su # mount -t cgroup -o memory none /home/vagrant/mem1 # mount -t cgroup -o memory none /home/vagrant/mem2 # cd mem1 # mkdir inst1 # ls inst1 cgroup.clone_children memory.failcnt ... # ls ../mem2 cgroup.clone_children inst1 memory.limit_in_bytes ... # cd inst1 # echo 1000000 > memory.limit_in_bytes # cat memory.limit_in_bytes 1003520 # cat ../../mem2/inst1/memory.limit_in_bytes 1003520 # echo $$ > tasks # cat tasks 1365 1409 # cat ../../mem2/inst1/tasks 1365 1411 > > Thanks. >
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