How to handle VMs using lots of CPU

Shadow Sysop

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Mar 7, 2021
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I'm still pretty new to Proxmox but have been learning rapidly. I have concerns with some user's VMs utilizing large, continuous amounts of CPU. I have been only allowing 75% for the CPU Limits (eg. A 4 Core VM will have a 3 as CPU limit. a 2 Core VM will have 1.5 as CPU limit). I've also been looking at CPU Units to possibly distribute weighted resources but haven't tried it yet. I notice a 4 Core VM using 100% cores will only utilize 75% of my actual CPU when setting CPU limits (still a bit high imo). Is this a good practice? How does this negatively affect user's VM? Can anyone recommend a better way to address this?
 
You could write a script that runs on the host, logs cpu utilization and dynamically adjusts the CPU limit. As far as I know you could change the CPU limit without stopping the VM.
That way you could give a VM 4 of 4 cores for short high CPU usage peaks but limit it slowly down to 2 of 4 cores on long term heavy CPU usage... maybe someone already coded something like that.
 
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You could write a script that runs on the host, logs cpu utilization and dynamically adjusts the CPU limit. As far as I know you could change the CPU limit without stopping the VM.
That way you could give a VM 4 of 4 cores for short high CPU usage peaks but limit it slowly down to 2 of 4 cores on long term heavy CPU usage... maybe someone already coded something like that.
Yes, you can adjust the CPU limit on a running a VM. This is actually an excellent idea.
 

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