KVM / CPU question

[locusofself]

Hello,
Given a server like this:

CPU(s)
24 x Intel(R) Xeon(R) CPU X5650 @ 2.67GHz (2 Sockets)


What would be a good CPU configuration for a virtual machine that has some CPU heavy tasks? I don't want to overload the host machine, but I'd like to give most resources to this VM.


Its a php task, so I don't really even know if adding more virtual sockets or cores will help. But I'd like to try.


Currently I had the VM set at 2 sockets and 2 cores per socket, and the result is that when the task runs, it shows 1 core pegged at 100% CPU in the VM, but on the proxmox summary tab of that node, it shows just 6% of the overall CPU being used, I guess just 1 core.

 

[dcsapak]

Currently I had the VM set at 2 sockets and 2 cores per socket, and the result is that when the task runs, it shows 1 core pegged at 100% CPU in the VM, but on the proxmox summary tab of that node, it shows just 6% of the overall CPU being used, I guess just 1 core.

if the task only uses one core in the vm, there is nothing you can do on the pve side to increase performance,

you can only try to rewrite the tool to use more threads/processes/etc.

but be aware of https://en.wikipedia.org/wiki/Amdahl's_law

 

[LnxBil]

Its a php task, so I don't really even know if adding more virtual sockets or cores will help. But I'd like to try.

You should consider to rewrite your task in a easily parallelizable programming language that is not interpreted to gain the most possible performance.