On Thu, Jun 23, 2016 at 08:33:18PM +0200, Peter Zijlstra wrote:
> On Fri, Jun 17, 2016 at 01:04:23AM +0200, Jirka Hladky wrote:
>
> > > What kind of config and userspace setup? Do you run this cruft in a
> > > cgroup of sorts?
> >
> > No, we don't do any special setup except to control the number of threads.
>
> OK, so I'm fairly certain you _do_ run in a cgroup, because its made
> almost impossible not to these days.
>
> Run:
>
> grep java /proc/sched_debug
>
> while the thing is running. That'll show you the actual cgroup the stuff
> is running in.
That'll end up looking something like:
root@ivb-ep:/usr/src/linux-2.6# grep java /proc/sched_debug
java 2714 18270.634925 89 120 0.000000
1.490023 0.000000 0 0 /user.slice/user-0.slice/session-2.scope
java 2666 18643.629673 2 120 0.000000
0.063129 0.000000 0 0 /user.slice/user-0.slice/session-2.scope
java 2676 18655.652878 3 120 0.000000
0.077127 0.000000 0 0 /user.slice/user-0.slice/session-2.scope
java 2680 18655.683384 3 120 0.000000
0.082993 0.000000 0 0 /user.slice/user-0.slice/session-2.scope
which shows a 3 deep hierarchy. Clearly these people haven't the
faintest clue about the cost of what they're doing. This stuff ain't
free.
