CPU Efficient-Cores (E-Cores) in VM

Does CPU Efficient-Cores (E-Cores) matter in Virtual Machine?

Who knows?

Many discussions on web and no obvious conclusion.

My basic take is who cares so long as vm performs well?

cereberus said:

Who knows?

Many discussions on web and no obvious conclusion.

My basic take is who cares so long as vm performs well?

Click to expand...

Agree -- main thing on VM's is ensure fast Disk I/O and enough RAM. These days CPU power isn't usually an issue unless you really overload the HOST's physical CPU. I'd suggest also where you can - pass enough hardware through to the VM so you can avoid any overhead due to paravirtualisation. Also if you have multiple HDMI or other GPU ports assign a separate one to the VM rather than sharing with the host.

(Also use more than the default nr of vCPU's if on Hyper-V -- default often set as 2 - but if you have 4 or 8 or more cores use that nr and if poss shared memory).

Cheers
jimbo

jimbo45 said:

Agree -- main thing on VM's is ensure fast Disk I/O and enough RAM. These days CPU power isn't usually an issue unless you really overload the HOST's physical CPU. I'd suggest also where you can - pass enough hardware through to the VM so you can avoid any overhead due to paravirtualisation. Also if you have multiple HDMI or other GPU ports assign a separate one to the VM rather than sharing with the host.

(Also use more than the default nr of vCPU's if on Hyper-V -- default often set as 2 - but if you have 4 or 8 or more cores use that nr and if poss shared memory).

Cheers
jimbo

Click to expand...

They seem to have updated the core selection i.e. it chooses how many be default by how many cores in Host CPU.

Performance Cores: 6 Cores, 12 Threads, 2.6 GHz Base, 5.4 GHz Turbo

Efficient Cores: 8 Cores, 8 Threads, 1.9 GHz Base, 4.1 GHz Turbo

Hyper-V selects 10 on this pc if I do not specifically set it but does not seems to differentiate betweeen Performance cores and Efficiency cores.

I guess Hyper-V tries to make a balance between selecting too few (slowing down vm) and selecting too many (slowing host and indirectly vm). Of course, I could be talking double gibberish here LOL.

cereberus said:

They seem to have updated the core selection i.e. it chooses how many be default by how many cores in Host CPU.

Performance Cores: 6 Cores, 12 Threads, 2.6 GHz Base, 5.4 GHz Turbo

Efficient Cores: 8 Cores, 8 Threads, 1.9 GHz Base, 4.1 GHz Turbo

Hyper-V selects 10 on this pc if I do not specifically set it but does not seems to differentiate betweeen Performance cores and Efficiency cores.

I guess Hyper-V tries to make a balance between selecting too few (slowing down vm) and selecting too many (slowing host and indirectly vm). Of course, I could be talking double gibberish here LOL.

Click to expand...

Hi there
If you have 12 or 8 Threads it pays to create the VM with the number of vCPU's to the number of physical CPU's. If multi threading isn't enabled / supported in physical BIOS (modern machines all support it these days) then use 1/2 the number of physical cores.

I can't mathematically prove this is the best combo but just enough trial and error with all sorts of VM's and various bits of hardware just lead me to this conclusion. I'm also not sure why one would use a CPU at 1.9GHZ base if it could be used at 4.1GHZ turbo -- some sort of overclocking to say around 3.0GHZ surely would be better - certainly if using VM's.

For my servers now I've decided to standardize on Debian 12.8 --- stable as a rock --everything works and I can just leave the whole kybosh running 24/7 - and keep W11 (native) and Archlinux on my laptops / test machines.

Testing on a MiniPC with 40TB of storage attached and running under decent load I haven't been able to "break" it yet or been pestered with "rolling release" updates. Working perfectly for Windows client backups, file serving, VM testing, multi media streaming etc. I've replaced 2X older HP servers (noisy, huge power consumption etc) with a couple of these boxes and they will I'm sure do the trick really well -- at a Black Friday sale at around €200 a pop -- who can complain -- particularly as servers can run headless -- and be controlled (as can Windows via cmd line using SSH).





Anybody whose thinking of a new machine and has their own keyboard/mouse/monitor should consider these (they come with W11 PRO ore-installed too if you want to run Windows on them).


Cheers
jimbo