Issue with Ubuntu CPU utilization

[iTerra]

Hi,

We’re experiencing the following problem with an Ubuntu VM:

The VM has 8 vCPU’s (switched from 2 sockets with 4 cores to 8 sockets with one core) and the latest VMware tools installed. Even though there’s a lot of workload on that system, the VM only seems to utilize about 25 % till 50 % of its CPU capacity. The return of the vmstat 1 command during that time is:

user: 28 %

system: 4 %

idle: 78 %

wait: 0 %

The vCenter statistics does show a spike on the CPU load, but the spike only climbs up and stays in between 25 and 50 percent or a maximal usage of 7,309 MHz (out of 16,000).

Here are some specs about the environment and the VM:

Server:

VMware ESXi 5.5

VMware vCenter 5.5

HP ProLiant DL380p Gen8

• 2x Intel Xeon E5-2620 @ 2.00 GHz
• 96 GB RAM
• QNAP-TS-869U-RP via iSCSI

VM:

Ubuntu 12.04.4 LTS (GNU/Linux 3.8.0-36-generic x86_64)

VM-Version 8

8 vCPU

8 GB vRAM

Up to date version of VMware tools installed

What can we do to improve the CPU utilization of that VM?

Please let me know if you need further information.

Thanks in advance

Christian

[Linjo · Accepted solution]

Since a thread can only use 100% of one vCPU it can be a threading problem on your application.

You should look at the individual cpu utilization instead of the overall consumption.

Lets say that the application can only use 1 thread but it uses that 100%, that means that it will use 12.5% of the total cpu resources allocated to this virtual machine. (100/8)

// Linjo

[Jayden56]

Hi

Welcome to the communities.

If its under utilization then I think nothing need to worry .

If you need to test CPU utilization could you please put more load \utilization.

[iTerra]

Thanks a lot for your quick responses and advice.

It seems to be a multithreading problem of the application that we're running on that server and not a VMware problem.