VM CPU kernel times too high

[Nikhil_Patwa]

Hello,

My ESXi 4.0 VMs are showing too high kernel times, is there a way I can reduce the kernel times. Kernel times directly affects I/O, does it mean too high kernel times means lot of I/O is utilized. The VM is mostly used for MS Office applications by some 15-20 remote users.

I would like to know ways on reducing the VM kernel times

Regards

Nikhil

[Linjo]

Is there any problems with the VM:s or a general question?

What hardware is this running and what storage-protocols are used?

Best regards,

Linjo

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[Nikhil_Patwa]

Hi,

My ESXi Host server is Dell PowerEdge T710 with 2 RAID 5 Datastores (8 x 146GB, 15K RPM disks & 8 x 300GB, 10K RPM disks)

The VM specifications are:

CPU = 4

RAM = 4GB

hosted in the 15K RAID 5 datastore.

Sometimes the servers becomes slow and while monitoring came to know the kernel times are very high. So far we have not faced any problems but am just curious to know what causes the kernel times to be so high and are there any ways to reduce it. Suprisingly the VM memory usage is very low.

Regards

Nikhil

[Linjo]

Depending on how many cores you have and how many virrtual machines it could be the problem with too many vCPU:s (4)

Since every time the virtual machine needs to do something the hypervisor needs to find 4 empty slots to run the machine on.

More vCPU:s does not mean more performance, quite frequently the other way around.

Try to reduce the vCPU:s from 4 to 2 or even 1 (depending on the workload) and monitor the CPU Kernel times.

Best regards,

Linjo

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[Nikhil_Patwa]

Have reduced vCPUs in some VMs but still the kernel times are too high, I could not figure out what causes the Kernel times to be so high.

The kernel times are not the same for all the VMs. I have seen kernel times in a VM accessed by many users in our office to be not so high and another VM that is accessed by only few users (2-3) to have high kernel times. Both the Vs have the same specifications interms of vCPU, memory

Need to figure out how to control kernel times, improve performance of virtual machines

Nikhil