Failed to set 8 virtual CPUs

[宋广斌]

The CPU of my laptop is 2.4 GHz 8 cores Intel Core i9。My VMware fusion software version is fusion Pro（12.2.4 (20071091)）。When I set the number of CPUs to 4, I enter the virtual system to view 2 slots and 4 virtual CPUs；When I set the number of CPUs to 6, I enter the virtual system to view 2 slots and 6 virtual CPUs; and， I set the number of CPUs to 7, I enter the virtual system to view 1 slots and 7 virtual CPUs。But，When I set the number of CPUs to 8, I enter the virtual system to view 2 slots and 4 virtual CPUs。WHY？？Ask experts for support，Thinks！！！ Note: My laptop‘s system is MacOS Ventura 13.0。

[Technogeezer]

I can't say for sure why Fusion is only assigning 4 virtual CPUs to your VM when you select 8.

What is the guest operating system in the VM, and what is the virtual hardware version (that's available in the VM's Settings under Compatibility).

However it is a very, very bad idea to assign more than n-2 virtual CPUs  - where n represents the number of physical cores - to a virtual machine. Hyperthreaded cores do not count!

The Mac needs to have resources available to run tasks on behalf of Fusion and the rest of whatever else you are running on your Mac. Assigning more than n-2 virtual CPUs will cause CPU contention and poor performance for both host and VM. 

That means for a 8 core Mac, do not assign more than 6 virtual CPUs to a virtual machine, even if it may let you assign more.

[宋广斌]

Thank you for your answer！！ the guest operating system is windows 11; and the virtual hardware version is 19. that's up to 16 virtual CPUs in the VM's settings under hardware. When you have more than 9 virtual CPUs, it will warn that you have set too many CPUs. Ask you said, If the number of virtual CPUs refers to the cores of physical CPUs(Hyperthreaded cores do not count!). Now, my CPU is 2.4 GHz 8 core(16 Hyper-threaded cores)Intel Core i9. Please give me an optimization suggestion about the number of virtual CPUs, Thinks!!

[宋广斌]

A new discovery. When I set the number of CPUs to 4, I enter the virtual system to view 2 slots and 4 virtual CPUs；When I set the number of CPUs to 6, I enter the virtual system to view 2 slots and 6 virtual CPUs; and， I set the number of CPUs to 7, I enter the virtual system to view 1 slots and 7 virtual CPUs。When I set the number of CPUs to 10, I enter the virtual system to view 2 slots and 10 virtual CPUs，When I set the number of CPUs to 12, I enter the virtual system to view 2 slots and 6 virtual CPUsBut，When I set the number of CPUs to 14, I enter the virtual system to view 2 slots and 14 virtual CPUs。When I set the number of CPUs to 16, I enter the virtual system to view 2 slots and 8 virtual CPUs。 It is abnormal when I set the number of CPUs to 8、12、16（8=4，12=6，16=8）. But, It is right when I set the number of CPUs to 10、14 and all singular numbers. Because when I set 10 or 14, its single slot is singular。So, I think this is a bug!

[ColoradoMarmot]

8 is too many for that hardware.  7 is the absolute maximum that you should set, and 6 is the max recommended on a modern operatin g system.

[宋广斌]

I mean, why does this happen（ It is abnormal when I set the number of CPUs to 8、12、16（8=4，12=6，16=8）. But, It is right when I set the number of CPUs to 10、14 and all singular numbers）. This is a bug

[Technogeezer]

Can you run 2 tests? One with 6 virtual CPUs and one with 8. Capture the vmware.log file found in the VMs bundle directory for each run and attach it to a reply. 

[宋广斌]

already send to your email。

[宋广斌]

Your message to community-noreply@vmware.com couldn't be delivered. A custom mail flow rule created by an admin at onevmw.onmicrosoft.com has blocked your message. Mail rejected

[宋广斌]

Please give me an email address you can receive, and I will send you the attachment

[scott28tt]

You can attach logs to posts, the option is just below the text editor.

[宋广斌]

the option is just below the text editor，No files can be added “Drag and drop here or browse files to attach Maximum size: 146 MB • Maximum attachments allowed: 10” This area cannot activate or add any files