vSphere virtual cpu speed built-in limit ?

[komanek]

Hello,

I have a cluster of four vSphere 4.0u1 hosts with plenty of free resources (4-core nehalem 2.27GHz + 32GB RAM for each host). There is a virtual machine (Debian 5 linux, 64bit) with one vCPU. Although this VM would like to have more CPU speed (triggering alerts on CPU usage), it never becomes more than about 2GHz. In the resource pool I tried add more shares (up to 8000), but with no luck

Is there a limit for vCPU speed in vSphere so that the only vay to increace computing pover of VM is to add another vCPU ? Or am I missing something basic where I can set the vCPU maximum for all my VMs ? I think the vCPU shloud be scalable in runtime up to 4x2.27GHz minus what service console needs, while other lesscpu usingVMs should be migrated to other hosts by DRS. Is it true or not ?

Thanks in advance,

David

[FranckRookie · Accepted solution]

Hi,

You will never have more than the power of a single core for each vCpu. At any time, each vCpu is attached to a physical core. The ESX scheduler do not aggregate the power of several CPUs to "emulate" a super processor.

In your configuration, every vCpu will never have more than 2.27GHz .

Franck

[komanek]

thank you very much