Any plans to increase the maximum number of virtual CPUs above 16?

[Simon Connah]

On 27/11/2018 23:06, Rodney W. Grimes wrote:
>> I was reading the bhyve man page and noticed that it said the maximum
>> number of virtual CPUs is limited to 16. With AMD Epyc being out with 32
>> cores and 64 threads per CPU and being able to have 2 of them in one
>> system this number seems rather low by modern standards.
> 
> So you can run 4 x 16 vcpu VM's, probably more common than
> someone trying to run 1 VM of 32 or 64 vcpu.
> 
>>
>> Are there any plans to increase this number to something like 32 virtual
>> CPUs?
> 
> There is work in process to change this from a compile time
> kernel constant to a per VM value set using the undocumnted,
> but present value in the cpu_topology option max_cpu.
> 
> We do not want to just crank this value up as data structures
> for each VM are sized on the MAXCPU connstant, and doubling
> that to 32 would be fairly wasteful for low core count VM's.
> 

Thank you for the reply.

Ah, that makes sense. Nice to know that it is something that is being 
worked on.

The only reason I really want to go above 16 vCPUs is that some other 
providers offer VPS instances with more vCPUs than that. I could quite 
happily live with 16 myself.