On Thu, 1 Sep 2016 14:48:39 +0200 Peter Zijlstra <pet...@infradead.org> wrote:
> On Thu, Sep 01, 2016 at 02:38:59PM +0200, Jesper Dangaard Brouer wrote: > > On Thu, 1 Sep 2016 14:29:25 +0200 > > Jesper Dangaard Brouer <bro...@redhat.com> wrote: > > > > > On Thu, 1 Sep 2016 13:53:56 +0200 > > > Peter Zijlstra <pet...@infradead.org> wrote: > > > > > > > On Thu, Sep 01, 2016 at 01:02:31PM +0200, Jesper Dangaard Brouer wrote: > > > > > > > > > PID S %CPU TIME+ COMMAND > > > > > 3 R 50.0 29:02.23 ksoftirqd/0 > > > > > 10881 R 10.7 1:01.61 udp_sink > > > > > 10837 R 10.0 1:05.20 udp_sink > > > > > 10852 S 10.0 1:01.78 udp_sink > > > > > 10862 R 10.0 1:05.19 udp_sink > > > > > 10844 S 9.7 1:01.91 udp_sink > > > > > > > > > > This is strange, why is ksoftirqd/0 getting 50% of the CPU time??? > > > > > > > > > > > > > Do you run your udp_sink thingy in a cpu-cgroup? > > > > > > That was also Paolo's feedback (IRC). I'm not aware of it, but it > > > might be some distribution (Fedora 22) default thing. > > > > Correction, on the server-under-test, I'm actually running RHEL7.2 > > > > > > > How do I verify/check if I have enabled a cpu-cgroup? > > > > Hannes says I can look in "/proc/self/cgroup" > > > > $ cat /proc/self/cgroup > > 7:net_cls:/ > > 6:blkio:/ > > 5:devices:/ > > 4:perf_event:/ > > 3:cpu,cpuacct:/ > > 2:cpuset:/ > > 1:name=systemd:/user.slice/user-1000.slice/session-c1.scope > > > > And that "/" indicate I've not enabled cgroups, right? > > Mostly so. I think RHEL/Fedora has SCHED_AUTOGROUP enabled, and you can > find that through: > > cat /proc/self/autogroup $ cat /proc/self/autogroup /autogroup-88 nice 0 > And disable with the noautogroup boot param, or: > > echo 0 > /proc/sys/kernel/sched_autogroup_enabled Looks like it is enabled on my system: $ grep -H . /proc/sys/kernel/sched_autogroup_enabled /proc/sys/kernel/sched_autogroup_enabled:1 > although this latter will leave the current state intact while avoiding > creation of any further autogroups iirc. $ sudo sh -c 'echo 0 > /proc/sys/kernel/sched_autogroup_enabled' $ grep -H . /proc/sys/kernel/sched_autogroup_enabled /proc/sys/kernel/sched_autogroup_enabled:0 $ sudo systemctl restart sshd Starting new SSH login: $ cat /proc/self/autogroup /autogroup-153 nice 0 Hmmm, still enabled... $ sudo systemctl stop sshd $ sudo systemctl start sshd $ grep -H . /proc/sys/kernel/sched_autogroup_enabled /proc/sys/kernel/sched_autogroup_enabled:0 $ cat /proc/self/autogroup /autogroup-158 nice 0 Still... enabled! Hmmm.. more idea how to disable this??? -- Best regards, Jesper Dangaard Brouer MSc.CS, Principal Kernel Engineer at Red Hat Author of http://www.iptv-analyzer.org LinkedIn: http://www.linkedin.com/in/brouer
