Different CPU usage in pfSense and vSphere



  • I have an issue that vSphere client and pfSense report different CPU utilization (see attached screenshots). This problem was discussed some time ago (https://forum.pfsense.org/index.php?topic=83428.0, https://forum.pfsense.org/index.php?topic=70092.0) but I could not find an actual explanation there. Those threads are quite old, so I decided to start a new one. The test case was a downloading on full speed with OpenVPN client enabled. vSphere client shows 100% CPU load and almost 7GHz used. pfSense shows 51% CPU load and the current CPU clock of 412 MHz. How can this be explained?

    ESXi host:

    • ESXi-6.0.0-20150902001-standard

    • SuperMicro X10SLM+-LN4F

    • Intel Xeon E3-1230v3

    • 16GB of DDR3 ECC Reg RAM

    pfSense VM:

    • pfSense 2.2.6-RELEASE (amd64)

    • 2 vCore

    • 1GB of RAM

    • 2 physical NICs (Intel® i210AT) passed-through to VM

    • Open-VM tools installed






  • i guess it is because the virtualmachine can't know the overhead the hypervisor gets.

    this is true in every OS you run in a virtual machine. the type of OS will generate different amounts  of overhead, depending on task its doing.



  • @heper:

    i guess it is because the virtualmachine can't know the overhead the hypervisor gets.

    this is true in every OS you run in a virtual machine. the type of OS will generate different amounts  of overhead, depending on task its doing.

    First of all, thanks for your reply, what you're saying makes sense. I thought that passing-through NICs would minimize the overhead, but if you're right - then I have 50% of overhead. This doesn't sound right to me, but I'm not an expert :) Do you have any ideas why pfSense shows that the current frequency is 412 MHz?