Re: [PATCH v4 2/2] cgroups: add a pids subsystem

From: Austin S Hemmelgarn
Date: Tue Mar 10 2015 - 07:32:45 EST

On 2015-03-10 04:10, Aleksa Sarai wrote:
Hi Austin,

Does pids limit make sense in the root cgroup?

I would say it kind of does, although I would just expect it to track
/proc/sys/kernel/pid_max (either as a read-only value, or as an alternative
way to set it).

Personally, that seems unintuitive. /proc/sys/kernel/pid_max and the pids
cgroup controller are orthogonal features, why should they be able to affect
each other (or even be aware of each other)?
I wouldn't consider them entirely orthogonal, the sysctl value is the limiting factor for the maximal value that can be set in a given pids cgroup. Setting an unlimited value in the cgroup is functionally identical to setting it to be equal to /proc/sys/kernel/pid_max, and the root cgroup is functionally equivalent to /proc/sys/kernel/pid_max, because all tasks that aren't in another cgroup get put in the root.

My only thought is that having the file that would set the limit there might make things much simpler for software that expects the entire cgroup structure to be hierarchical.

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at