vCPU prioritization and CPU entitlement

[Jeromejay]

Hello,

Here is a quick description:
We have 4 virtual guests, running on 8 vCPU.

For now, we have basically allocated 2vCPU with entitlement 10 to 100% for each virtual machine.

However, in the course of time, we noticed that:
- 2 virtual machines are almost always idle (we get a CPU spike for each user logging in, but then, the CPU is idle)
- 1 virtual machine is heavily loaded (CPU-wise): almost 100% all the time
- 1 virtual machine is right in-between (CPU spiking when guests login, and at ~50% load after that)


=> Obviously, we are wasting CPU time, since 4vCPU are idle, 2 are too loaded, and 2 are in between.


The idea is:
I would like to, somehow, allocate the idle time of the 2 idle vguest to the one that is too loaded.
However, I want those 2 idle machines to be able to take back this CPU power when necessary (when a guest login).

=> How can I "prioritize" the 2 idle guests ?


just rephrasing the same question:
I was thinking of allocating 2vCPU to the "in between" guest, and the remaining 6vCPU to the 3 other guests.
What I fear is that the heavily loaded guest will eat all the ressources available, and the 2 other will have nothing left when they need a CPU spike.



I know I can play with vCPU allocation and entitlement, but I'm not sure of a few things:
can I exceed the max entitlement somehow ? (ie: what if I tell the 4 guests to have 8vCPU each, and 50% CPU entitlement for each vCPU). What will happen then ?

What would be the best way to allocate the vCPU on those machines ?

Thanks for your help,

[Vivek_Pendse]

I think, prioritization of vpus is not possible across guests allocation.

Still you can assign "cummulative/all" vpus to guests & define the minimum entitlement depending upon their loads.

So, wherever cpu cyles are free & the guest is demanding then can manage of their own till 100% of assigned (all) cpus.

Or, you can check performance by assigning a full vcpus with full entitlement for crunch cpu guests & rests you can entitle in % assignment.

Thanks,
Vivek

[Duncan Edmonstone · Accepted solution]

Maybe you should consider using gWLM to manage your entitlements? This can adjust entitlements based on policies/priorities between the different VMs.

This whitepaper should be a useful introduction:

http://bizsupport2.austin.hp.com/bc/docs/support/SupportManual/c02018662/c02018662.pdf

HTH

Duncan

[Vivek_Pendse]

Hi,

gWLM is a good solution.

Also, there is a new product from HP called "Blade Support Matrix for HP-UX", which you can think of. And, it's a good product for development sites.

Thanks,
Vivek

[Duncan Edmonstone]

Vivek,

>> Also, there is a new product from HP called "Blade Support Matrix for HP-UX",

I'm pretty sure you meant "BladeSystem Matrix with HP-UX" :

http://h18000.www1.hp.com/products/quickspecs/13755_div/13755_div.html

That includes gWLM under the covers and in fact gWLM would be the tools doing the resource allocation in BladeSystem Matrix as well.

HTH

Duncan

[Vivek_Pendse]

Ohh.. was not aware of it.
But, will get a chance to work on it soon :)