[lxc-users] LXC reports memory usage as 0

[Dwight Engen]

On Tue, 7 Jan 2014 13:44:36 -0800
Allan Caffee <allan.caffee at gmail.com> wrote:

> I'm trying to use lxc to limit the memory that can be consumed by a
> process, but when I run something with a container all of the
> resource usage statistics
> report back as 0.
> 
> I'm using the following config for my container:
> 
>     lxc.cgroup.memory.soft_limit_in_bytes = 512M
>     lxc.cgroup.memory.limit_in_bytes = 512M
>     lxc.cgroup.memory.memsw.limit_in_bytes = 1G
> 
> And when I create the container and start an app inside of it I can
> see that the limits are reflected by the container, but the current
> values always report as 0:
> 
>     $
> head /cgroup/lxc/large-app/memory.{limit_in_bytes,usage_in_bytes}
> ==> /cgroup/lxc/large-app/memory.limit_in_bytes <== 536870912
> 
>     ==> /cgroup/lxc/large-app/memory.usage_in_bytes <==
>     0
> 
> When I look up one directory in "/cgroup/lxc" the usage also appears
> to be 0, but
> when I go all the way to the top level "/cgroup" directory I get
> stats that seem
> to accurately reflect the system stats as a whole.

Maybe check /cgroup/memory/memory.use_hierarchy? I've seen where that
isn't set to 1 and thus lxc can set it to 1 at lower tree levels.

> I'm running RHEL 6.1 and lxc version 0.9.0. And the system appears to
> be configured to support cgroups:
> 
>     $ lxc-checkconfig
>     Kernel configuration not found at /proc/config.gz; searching...
>     Kernel configuration found
> at /boot/config-2.6.32-131.4.1.el6.x86_64 --- Namespaces ---
>     Namespaces: enabled
>     Utsname namespace: enabled
>     Ipc namespace: enabled
>     Pid namespace: enabled
>     User namespace: enabled
>     Network namespace: enabled
>     Multiple /dev/pts instances: enabled
> 
>     --- Control groups ---
>     Cgroup: enabled
>     Cgroup namespace: enabled
>     Cgroup device: enabled
>     Cgroup sched: enabled
>     Cgroup cpu account: enabled
>     Cgroup memory controller: enabled
>     Cgroup cpuset: enabled
> 
>     --- Misc ---
>     Veth pair device: enabled
>     Macvlan: enabled
>     Vlan: enabled
>     File capabilities: enabled
> 
>     Note : Before booting a new kernel, you can check its
> configuration usage : CONFIG=/path/to/config /usr/bin/lxc-checkconfig
> 
> Thanks in advance for any help you can provide.
> 
> --
> Allan