VM's very slow after mainboard change


Active Member
Dec 11, 2019

I have a PVE installation here (7.4-17). After the motherboard broke I replaced it. Previously, an AM3 board with a 6-core CPU was installed. I have replaced this with a dual Xenon board with (a total of) 8 cores. The LSI 8 port RAID controller incl. storage (4 x 1TB SSD / RAID5) I took over 1:1.

Since the VM's CPU was/is set to "kvm64" there were no problems. The VM's are exclusively Linux (pfSense, UCS).

These VM's are now significantly slower than before. This is already noticeable when the VM boots. Do I have to do or pay attention to other steps after the mainboard change?

with best
What CPUs do you got? 4 core Xeons sounds like they are very old and the single-threaded performance will probably not be great. Also make sure to enable NUMA when working with multiple sockets. When one CPU is trying to access ressources connected to the other CPU you will see a performance hit. So I wouldn't assign more than 4 vCPUs per VM.
Yes, the board/CPU is a bit older:

Intel(R) Xeon(R) CPU E5450 @ 3.00GHz

On NUMA is activated or can I must look tonight. The VM has 2 sockets / 2 cores


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