ESXI 6.7 U3 Dual EPYC system

[Rp42Systems]

Hello everyone,

Currently i have a problem with a dual EPYC system and it is a tricky one. (EPYC 7502 32 core, 64 virtual)

I got 2 VM's (windows 10 pro) with 2 quadro cards passthrough and each VM have 64 vCPU's but when i run V-RAY benchmark just for the CPU on the VMs at the same time the score is around 23k but if i run one at a time it goes to 32k of score.

I don't know why the performance dips so much and i don't know if ESXI is confusing with the dual cpu and just trying to do everything on one.

I've already tried setting each VM with 32 cores per socket, 64 vCPU's and i get a score of 25k.

[Rp42Systems]

UPDATE: I only added the EPYC CPU's into this topic but this can go to a general topic of a dual CPU system

[larstr]

r42systems,

I don't have a definite answer for you here, but as you're trying to put all cpus to maximum load they are probably running at a lower GHz than if you only ran the test on a single VM. This is typically power (psu) and heating related. Be also aware that the turbo boost is also only available if only a certain amount of cores have high load.

Lars

[Rp42Systems]

Hi larstr,

I did thought about that, and i did a test with a single socket system (same CPU, same ram, etc) and it actually worked beautifully and got the score of 32k on both VM's running them at the same time.

It's only on a dual socket system this happens.

[larstr]

RP42Systems,

That is very strange. Have you used esxtop to monitor the physical cpu load while the tests are running? Have you disabled C-states in your BIOS?

Lars

[Rp42Systems]

Hi larstr,

I have disabled C-states in the BIOS and it did mess up some other settings but never the less the scores didn't do anything.

Esxtop didn't gave any news, looked to be stable.

Although when i tweaked with cTDP and setup both VM's to 32 cores per socket and 32 vCPU the scores bumped to 28k.
It's weird, it is as is when the physical cores are put into the VM's it works fine (with low scores of course) but when running any virtualized cores on a 2 socket motherboard then ESXI does something weird.