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davidcrowder
Enthusiast
Enthusiast

Strange CPU Consumed

We have a new vSphere/ESXi host, and I have been noticing that the guest CPU activity is often far below the host CPU activity.  Here is a representative screen shot from webgui:

Untitled.png

As you can see, CPU 0 & 1 are at around 40-41%, while the combined guests are 26%.  While this is not yet a problem, as this server grows and sees more usage, this will become a problem.  I'd like to solve it before then.

From the notes below, Guest #1 is the only that is actively in use.  Perhaps there is something in its configuration that is leading to over-consumption of the host CPU...?

Any ideas?

The hardware / basic setup is below:

Running ESXi 6.5.0 U1 build 5969303

System Board:  Supermicro SYS-1029P-WTR

CPU: (2x) Intel Xeon Gold 6144 (8 physical cores each, 16 hyper-threaded)

Memory:  192 GB memory

Storage:  (2x in RAID-1) 1.6 TB SAS SSD via LSI 9361-8i, configured in single datastore

Network:  Single 10G network card, used for both management and guests

Currently only three guests.  All have the guest-tools installed and running.

#1 Win 2012 R2

#2 Win 2016

#3 Win7

Guest #1 was originally bare-metal, and was P2V using VMWare's tools.  It is used as a Remote Desktop Server.  It sees spurts of CPU activity, and is not disk or network bound.  It is allocated 28 vCPU's, 64 GB memory, 200 GB disk in a thick-provision.

Guest #2 is a new VM, and is currently in pre-production.  It is allocated 8 vCPU's, 64 GB memory, 200 GB disk in a thick-provision.

Guest #3 was originally bare-metal, and was P2V using VMWare's tools.  It is lightly utilized by our phone system for admin purposes.  It sees little activity for CPU, disk or network.  It is allocated 2 vCPU's, 4 GB memory, 220 GB disk in a thick provision.

Thank you in advance.

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davidcrowder
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Enthusiast

After testing various settings, I finally reduced the core-count to 16 (2-sockets, 8 cores per socket).  With this configuration, when VM #1 has CPU usage at 40%, the host system shows CPU usage at 40%.  No more mystery overhead.

This leads to a follow-up question:

Does VMWare require me to base guest vCPU count on base-2  (2^x)?  Or, does it require me to base vCPU count on the host architecture's physical CPU core count (if the host has 8-core CPU's, the guest should be multiples of 8)?  Or is something weird going on here?

Thanks,

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