Hi Steven, Thanks a lot for your reply. It’s higher about 16% usr, 34% sys in top output but as I observe pidstat has no any process consume this high cpu usage. After reboot it can happen on a certain core on a certain VM, not fixed to any core. For ftrace, I mean function profile tracer by echo 1 > /sys/kernel/debug/tracing/function_profile_enabled I will try your suggestion. Thanks again, Brs, Naruto On Tue, 18 Jun 2019 at 20:02, Steven Rostedt <rostedt@xxxxxxxxxxx> wrote: > > On Tue, 18 Jun 2019 18:40:13 +0700 > Naruto Nguyen <narutonguyen2018@xxxxxxxxx> wrote: > > > Hello everyone, > > > > I have a kvm hypervisor and setup some VMs running OpenSUSE kernel > > 4.0. After some reboot, I saw that sometime there is a VM that a > > certain core has higher %usr and %sys than other cores. The system is > > in ide state. I have some applications running on this VM, but there > > is no issue in other VMs. > > How much higher? And is it always an issue with the same core on the > same VM? > > > > > If I enable ftrace in kernel or load any debug jprobe, the load is > > I'm assuming by "ftrace" you mean the full function tracer? > > # echo function > /sys/kernel/tracing/current_tracer > > > back to normal. The pidstat command output does not show the high load > > on one core like the "top" command. Could you please let me know if it > > is the problem of "top' report higher usage? Any commands that can > > help to troubleshoot this issue? I tried "perf" but most of the time > > the perf output does not show any function that cause the increase as > > well? Not sure, if the malfunction of top or anything else can add > > more work load? > > I would suggest just tracing sched switches and interrupts. That > shouldn't affect the load, as it is very low weight. > > # cd /sys/kernel/tracing > # echo 1 > events/sched/sched_waking/enable > # echo 1 > events/sched/sched_switch/enable > # echo 1 > events/irq/enable > > And then monitor that. > > -- Steve
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