HostCPU is near idle nevertheless the VM are extremely slow

[ozzproject]

Hello,

I am using the latest version of ESXi on my home server. Currently these are two virtual machines.

One with Windows 7 and 10 (MySql Server).

Currently I have the problem again and again, that the assigned HostCPU is with few Mhz (sometimes 12 MHz) and very fluctuate (although on the computer some jobs run)

As a result, the two machines cannot communicate correctly with each other (timeout).

The average CPU utilization in the VSphere Center is 20%.

The following configuration:

Both machines have 2 CPU assigned (2:1)

ESXi Reservation 500 mhz (for the CPU)

Both machines I have deactivated the power saving mode

Also on the ESXi host

CPU on the ESXi host one Intel Core i7 8550U (Core 4 / 8 thread)

How do I prevent that the computers get so little CPU time or that the existing CPUs are also exploited (the computers actually have enough to do)?

[KocPawel]

Check other parameters like CPU Ready.

Check this a nd take a look on your system:

http://www.running-system.com/wp-content/uploads/2015/04/ESXTOP_vSphere6.pdf

Also check in BIOS if your CPU has something like Power Saving mode enabled.

[Ardaneh]

Hi

When you check the CPU performance of an ESXi host, you should consider more counters. by using esxtop command in your esxi shell you can find out more about your VMs CPU performance. there are two important counters: RDY and CSTP for each VM

if these counters are showing with high numbers, it means that your VMs are facing some CPU problems and in your ESXi web client, the progress bar for CPU usage shows a big percentage of free CPU. so the solution is to check your VMs CPU configuration and ESXi power profile. I put some hits down there:

- It's better to keep the size of your VMs CPU as small as you can and also the same, for example, 2 VMs with 4 vCPU for each is better than 2 VMs with 2 vCPU and 6 vCPU. (you can search for CO-Scheduling process for more information)

- It's better to change your esxi power profile to High Performance (If you have big workloads)

- It's better to use virtualized hardware components for your VMs (VMXNET3, ISCSI Paravirtual controller) to reduce CPU overhead.

I hope this could help you to solve your problem

cheers

[ozzproject]

Hi KocPawel,

thanks for the link.

I have done the trace for on day. %Rdy for all VM is below 0.20, %SWPWT is zero and also MLMTD

[Acry27]

Hi OzzProject,

Did you check Memory & also the storage performance ?

Are you sure your performance issues are due to CPU ?

Regards,

bbes

[larstr]

ozzproject,

What is your ESXi version? vsish -e get /system/version

Is powersaving options completely disabled or do you still have acces to cpu turbo modes?  vsish -e get /Power/hardwareSupport    <- on 6.7. On 6.5 you will have to run:  vsish -e get /power/hardwareSupport

Lars

[ozzproject]

Hi Lars,

i run this version

   product:VMware ESXi

   productVersion:6.7.0

   buildVersion:Releasebuild-15018017

   buildType:Release

   buildVersionNumeric:15018017

   releaseUpdate:3

   releasePatch:77

   buildDate:Nov  4 2019

   buildTime:19:07:27

   cpu architecture:CPU architecture: 1 -> x86_64

   vmkernelBuild:15018017

   vmkcall:InterfaceVersion {

      major:45

      minor:0

and the power Management is disabled in Esxi.

The anwser of vsish -e get /power/hardwareSupport is

-- CPU power management:ACPI P-states, ACPI C-states

[ozzproject]

Hi Arcy27,

yes, i checked it Storage is fine and also the memory.

if i am sure , the performance issue are due the CPU... no.

but take a look at the performance counter

[larstr · Accepted solution]

Very good, ozzproject.

Please reboot your server and disable C-states from your BIOS configuration. It will make a big impact on your performance.

Lars

[ozzproject]

Hello Lars,

I deactivated the power management in the bios and restarted the server.

Currently all VMs are assigned to 44 Mhz or less.

i am run again vsish -e get /power/hardwareSupport

Hardware power management support {

   CPU power management:ACPI P-states, ACPI C-states

}

[larstr]

It doesn't look like you've managed to disable C-states completely as it still lists "ACPI C-states" as an available feature. Have you tried updating your BIOS to see if it gives you more options?

Lars

[ozzproject]

Hi Lars,

Yeah, I saw it, too.

I looked in AMI Bios again. The energy saving option is on high perfomance (previously non top performance) and I have disabled all available C.Modes (C1 to C3).

But I already have the improvement and the system is now at least stable.

Thanks for the help

[larstr]

Very good! Not all C-states have equally bad negative impact for performance so I guess you found the important ones.

Lars