Hi Peter, thanks a lot for looking into it!
I have tried to disable autogroups sysctl -w kernel.sched_autogroup_enabled=0 and I can confirm that performance is then back at level as in 4.6 kernel. I have double checked default settings and kernel.sched_autogroup_enabled is by default ON both in 4.6 and 4.7 kernel. Jirka On Thu, Jun 23, 2016 at 8:43 PM, Peter Zijlstra <pet...@infradead.org> wrote: > 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. > >
