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VMWare, number of vCPU
I know I am a little slow about this, but I have been experimenting, and yes, my VM's perform better with less vCPU, instead of more, especially when they are not running at a high CPU utilization
So from reading the posts and the documentation, what I am gleaning is that the scheduler is swapping the vCPU'sfrequently, and with less vCPU it basically swaps less often,a nd can obtain a higher performance.
Is this correct. Can anyone enlighten me as to the 'core' reasons less vCPU seems to improve performance.
So from reading the posts and the documentation, what I am gleaning is that the scheduler is swapping the vCPU'sfrequently, and with less vCPU it basically swaps less often,a nd can obtain a higher performance.
Is this correct. Can anyone enlighten me as to the 'core' reasons less vCPU seems to improve performance.
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Andrew Hancock (VMware vExpert PRO / EE Fellow/British Beekeeper)
less time spent waiting for cpu states.
If you are over allocated more vcpu just makes it worse
Only add vcpu not counting hyperthreading.
It really depends on your boxes and vms how to best set this up. For example, I have a osx vm for Xcode compiling runnin on an Xserve. I gave it 4 vcpu because it can compile multithreaded.
I also have a mailserver that would run at 90% inside the vm with one vcpu which was basically maxing one core of the real CPU. So I gave it two vcpu and now it's running at 30%. Whatever, it's happy. The general rule is as few as possible. Most of my vms are 1vcpu.
Only add vcpu not counting hyperthreading.
It really depends on your boxes and vms how to best set this up. For example, I have a osx vm for Xcode compiling runnin on an Xserve. I gave it 4 vcpu because it can compile multithreaded.
I also have a mailserver that would run at 90% inside the vm with one vcpu which was basically maxing one core of the real CPU. So I gave it two vcpu and now it's running at 30%. Whatever, it's happy. The general rule is as few as possible. Most of my vms are 1vcpu.