So I accidentally had CPU host passthrough AND emulated QEMU64 running on the same cores.  I had believe that passthrough was like locking the guest to those cores physically.  However after thinking about it for a bit, i thought maybe emulated was more around getting a reduced but more consistent set of CPU extensions so that virtual machines can be live migrated.

 

So if host passthrough allows more CPU extensions to be passed through (and it does), is there anything stopping me from running all my VM's in host passthrough mode even if they touch the same cores simultaneously?

 

Does anyone have a definitive answer?  I'm still googling, but haven't come up with anything yet.

 

Many thanks,

 

Marshalleq

16 hours ago, Marshalleq said:

So if host passthrough allows more CPU extensions to be passed through (and it does), is there anything stopping me from running all my VM's in host passthrough mode even if they touch the same cores simultaneously?

no, you can stack as many vm's on a core as you want but will pay a penalty in performance and latency.

 

 

Yes, of course, however I'm just particualrly referring to the difference of host pass through vs emulation of the CPU.  I though host passthrough locked those cores for exclusive use, but I'm now thinking it doesn't.