topic VM CPU entitlement optimization in Operating System - HP-UX

VM CPU entitlement optimization

Kasper_USB — Tue, 09 Feb 2010 15:04:51 GMT

Asume the given VM's
[Virtual CPU entitlement]
Percent Cumulative
Virtual Machine Name VM # #VCPUs Entitlement Maximum Usage Usage
==================== ===== ====== =========== ======= ======= ================
vm1 1 4 50.0% 100.0% 1.1% 32206919
vm2 6 4 50.0% 100.0% 33.6% 494727237

on the given VM-Host:

hpvmstatus -s
[HPVM Server System Resources]

Processor speed = 1595 Mhz
Total physical memory = 131040 Mbytes
Total number of processors = 8
Available memory = 12275 Mbytes
Available swap space = 72996 Mbytes
Maximum vcpus for an HP-UX virtual machine = 8
Maximum vcpus for a Windows virtual machine = 8
Maximum vcpus for a Linux virtual machine = 8
Available entitlement for a 1 way virtual machine = 1595 Mhz
Available entitlement for a 2 way virtual machine = 1595 Mhz
Available entitlement for a 3 way virtual machine = 1595 Mhz
Available entitlement for a 4 way virtual machine = 1595 Mhz
Available entitlement for a 5 way virtual machine = 797 Mhz
Available entitlement for a 6 way virtual machine = 797 Mhz
Available entitlement for a 7 way virtual machine = 797 Mhz
Available entitlement for a 8 way virtual machine = 797 Mhz

To spend more CPU-Resources (Power) to vm2 (wich is more loaded) is to reduce the maximum entitlement from vm1 to 50% and the minimum to 25% ?

Is this a good way ?

Re: VM CPU entitlement optimization

Steven E. Protter — Tue, 09 Feb 2010 15:41:38 GMT

Shalom,

This will work as you say. Right now you have 50% maximum for your two virtual environments.

I see no reason to make any changes unless you have issues with performance actually running the systems.

SEP

Re: VM CPU entitlement optimization

Eric SAUBIGNAC — Mon, 15 Feb 2010 09:25:08 GMT

Bonjour Kasper,

I think it is a bit more complicated

You have 8 physical core, each VM has 4 vCPU.

Let us suppose that at a given moment vm1 relies on physical cores 0 to 3, and vm2 relies on cores 4 to 7. (Not so obvious, but we can suppose)

Lest us suppose now that vm1 and vm2 require both the maximum availaible CPU. Lowering vm1 to 25/50 % will not help to give more power to vm2, because at this moment vm2 has the maximum possible power : 100% of 4 core, that is 50 % of the whole box.

And this exemple is the better situation you can expect, because you will find that sometimes vm1 and vm2 share some cores.

Suppose now that vm1 and vm2 shares the same 4 cores. Suppose again that vm1 and vm2 require the maximum availaible CPU. Because vm1 has an entitlement of 25% and vm2 an entitlement of 50%, it means that vm2 will get 66,67% of 4 core, it means 33,33% of the whole box.

In a summary, with the configuration you have described, vm2 can expect a maximum of CPU between 33,33% and 50% of the whole box.

So if you want that vm2 can have more than 50% CPU of the whole box, you should increase the number of vCPU of this VM.

You can do that online, from inside the vm, with command "hpvmmgmt -c #'. Not correctly documented, so see Release Notes, T2767-90797.pdf, page 59/120

Hope this will help

Eric

Re: VM CPU entitlement optimization

Kasper_USB — Tue, 23 Feb 2010 15:54:11 GMT

Thanks to all comments.
Was usable for me.
We tried with min 5% max 10% and min 50% max 100% on the other. ->10% definitvely the system goes no more.
Then we go to min 5% and max 50% and min 50% max 100%.
So we ensure that the Resources of the max 50% VM goes to the other (up to 95% max) it the other VM needs the resources.
Its only a small improvement, but better than nothing. In addition we understand more the entitlement functions and ther usability in customer environment.
regards Olaf