Manually adjust CPU frequency

[cetbal]

I have a ESXi 5 server for development purposes and I use an Intel Core i5 2500k CPU overclocked at 4.3 GHz (from 3.3 GHz).

However ESXi does not recognize the actual frequency and therefore the maximum reservation frequency is limited to less than 12 GHz (which should be at approx. 16 GHz).

Is there any way to manually change the hosts cpu frequency?

Thanks in advance.

[11satya]

hear is the link

http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1010184

_________________________________
Good luck!

[cetbal]

Thanks, but I can't see how that link helps me.

The 4 Cores of my CPU are recognized but the speed is wrong.

[zahidm]

http://jhansonxi.blogspot.com/2008/09/improving-windows-xp-guest-in-vmware.html

hope this will help you

[weinstein5]

Welcome to the Community - I have never heard of anyone over clocking a CPU on an ESX host - I think the issue comes from the fact that the ESX server might not be looking at the actual clock speed but what the speed the CPU thinks it is running at - 

[cetbal]

Thanks again for the help.

I don't want to set the correct cpu frequency on each virtual machine separately.

What I'm trying to do is setting the host frequency to 4.3 GHz because I can't make the right reservations (ESXi shows about 12GHz in total but I have ~17GHz).

Maybe there is a way to set the correct frequency directly in the hosts' filesystem? As far as I know the host is running a Red Hat Linux version but sadly I don't have any experience with that distribution.

[weinstein5]

That is one of the misconceptions - the host is not running Red Hat - ESXi was built from the ground by VMware when it there was ESX where was portion of the install that was a modified version of Red Hat but that is no longer used with vSphere 5 - I am curious why did you iverclock the server?

[golddiggie]

I would imagine (knowing how ESXi works) that you'd need to perform any overcrocking at the bios level, or at the hardware level, in order for ESXi5 to recognize it. Trying to go into the hypervisor and mucking around there, without knowing what you're doing (to the Nth degree) is simply a bad idea. Not to mention you would probably need to make the change with every update/patch made on the host. The chances of remaining 100% static on the host software level is rather remote.

IMO, if you need more CPU resources, then you should add them with actual hardware, not try to cheat. You would probably have more than you need if you had dual sockets (quad core, or more, each).

What is the hardware that you've installed ESXi5 onto? Is this an actual server (doubt it from what you've already posted), a desktop, or a whitebox system? What are you planning to run on the host where you're making CPU/MHz reservations on?

BTW, at 3.3GHz per core, you should have about 13.2GHz total. Minus what ESXi5 will use will be available for VM's.

[cetbal]

The system has desktop components + a server raid controller and it is only used for development puposes.

The cpu is overclocked at the bios level and stability is not an issue - I'm overclocking cpus since years. So please focus on my question. :smileywink:

With 4.3 GHz it almost has the performance of a 6-Core Intel Core i7 with 3.33 GHz at 1/3 of the price. Why should I buy a more expensive CPU for testing?

I have about 12 GHz showing up in vSphere (4x 3.3 would be 13.2 GHz) so I guess ESXi uses about 10% of the total power.

[Dave_Mishchenko]

Have you tested a VM to see if its vCPU is running close to the overclocked value (i.e. using a CPU stress tool)?  Or is your problem limited to setting CPU reservations?

[cetbal]

Windows boots up with the original CPU and if I stress the CPU vSphere shows a usage of about 17.2 GHz.

Yes, I have the overclocked performance but no, I can't make the correct reservations.