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understanding total CPU used on a RedHat VM running in Hyper-V 2012 host

SysEngSysEng Posts: 1
in System Management

I have a Red Hat Enterprise Linux Server release 6.4 (Santiago) [Linux 2.6.32-358.11.1.el6.x86_64 x86_64 x86_64 x86_64 GNU/Linux] virtual machine running on Hyper-V 2012 hypervisor. We have a SCOM monitor that monitors CPU usage on that VM and it continuously reporting that the CPU being used is at around 98%. When I log onto the VM and run "top" command, it shows 74.6%id (idle?) meaning that only 25.4% of total CPU on the VM is being used, right? In Windows it is very easy to see the total amount of CPU being consumed by the system, but in Linux it is a bit confusing.

What's even more confusing is that a different command, like "mpstat -P ALL" shows a different amount of CPU usage.

So my question is, how do I see the total amount of CPU being used at the moment on a Linux system?



top - 11:18:00 up 212 days, 1:47, 54 users, load average: 5.16, 5.21, 5.21

Tasks: 416 total, 6 running, 410 sleeping, 0 stopped, 0 zombie

Cpu(s): 12.0%us, 13.2%sy, 0.0%ni, 74.6%id, 0.0%wa, 0.2%hi, 0.0%si, 0.0%st

Mem: 3916152k total, 3810532k used, 105620k free, 112396k buffers

Swap: 4063224k total, 28208k used, 4035016k free, 3375732k cached



Linux 2.6.32-358.11.1.el6.x86_64 (machine) 05/12/2016 _x86_64_ (4 CPU)

11:21:19 AM CPU %usr %nice %sys %iowait %irq %soft %steal %guest %idle

11:21:19 AM all 4.91 0.00 5.68 1.63 0.07 0.06 0.00 0.00 87.65

11:21:19 AM 0 1.97 0.00 1.88 2.19 0.27 0.16 0.00 0.00 93.53

11:21:19 AM 1 15.92 0.00 19.98 1.10 0.00 0.03 0.00 0.00 62.98

11:21:19 AM 2 0.88 0.00 0.47 1.67 0.00 0.03 0.00 0.00 96.95

11:21:19 AM 3 0.90 0.00 0.43 1.58 0.00 0.03 0.00 0.00 97.06

Comments

  • imortimort Posts: 5

    Hey

    It could be challenging to monitor Linux resources usage, especially after mostly Windows experience.

    I can remember that feeling myself to be honest.

    What you need to looking for is a load average for your host first: load average: 5.16, 5.21, 5.21

    The rule of thumb here is that it should not be higher than total numbers of your server core.

    You also looking at the total CPU load on the 'top' utility output. Press the 'S' key to see how the load distributes over the CPU cores.

    Looking at your top utility output I can say that you either have some CPU hungry processes with peaks of CPU using, or the disk/network is a bottleneck here (unlikely because the wait average (%wa) is about zero here)

    You can look here for more explanations about how to debug Linux servers resources consumption and problems.

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