is there a vCPU hard limit for bhyve guests?

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is there a vCPU hard limit for bhyve guests?

tech-lists
Hi,

On a host with hw.ncpu=48 I tried to start a bhyve guest with -c 24 and
it failed to start. So I tried -c 16 and it starts and runs as
expected. Any more than -c 16 fails to run.

Is a maximum of 16 vCPU hardwired somewhere, and if so, why? Is there a
way to overcome the limit?

thanks,
--
J.
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Re: is there a vCPU hard limit for bhyve guests?

Rodney W. Grimes-4
> Hi,
>
> On a host with hw.ncpu=48 I tried to start a bhyve guest with -c 24 and
> it failed to start. So I tried -c 16 and it starts and runs as
> expected. Any more than -c 16 fails to run.
>
> Is a maximum of 16 vCPU hardwired somewhere, and if so, why? Is there a
> way to overcome the limit?

man bhyve
Look at -c option, default is 1 max is 16.

There is a compile time constant VM_MAXCPU, you can raise that
to 20, then other problems come about that require more patching.

Last time I played with this it failed above 16, I suspect
some other places have had a bad derived constant using the
assumption that 16 is the max.

> thanks,
> --
> J.
> _______________________________________________
> [hidden email] mailing list
> https://lists.freebsd.org/mailman/listinfo/freebsd-virtualization
> To unsubscribe, send any mail to "[hidden email]"
>

--
Rod Grimes                                                 [hidden email]
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