bhyve max CPUs in bhyve?

oodler

oodler

I can't seem to get a Debian instance started > 16 CPUs. I am on a system that has 40 physical CPUs, 80 as recognized by FreeBSD (13.1) due to hyperthreading. I'd like to capture 32, 48, or even 64 of these processors under a bhyve VM. Good people, please advise.

Update: It seems when I had my issues, I was not running 13.2 yet. I upgraded before I tried again just as a normal thing not to get the increased CPU support; but that came along with it.
 
See bhyve(8):
Code: 
     -c [setting ...]
                 Number of guest virtual CPUs and/or the CPU topology.  The
                 default value for each of numcpus, sockets, cores, and
                 threads is 1.  The current maximum number of guest virtual
                 CPUs is 16.  If numcpus is not specified then it will be
[...]

oodler said:
please advise.
Click to expand...
Hm. Stick with 16 vcpus? Use a different hypervisor? Wait for a new FreeBSD version?
 
Yep, I just found out the hard way (grepping the source tree) ... it is configurable now in a tunable hw.vmm.maxcpu. (the manpage should certainly mention that ....)

So, check your current limit with sysctl(8).

To bump it up, you must do so before loading vmm(4), so, either from /boot/loader.conf, or manually before loading the module using kenv(1).
 
Thank you, this is great news. I am running 32 CPUs now but need to see if I can increase that. I didn't have to set any sysctls to get there. And indeed, here is the answer:

Code: 
pontius@jail-host:~ $ sysctl hw.vmm.maxcpu
hw.vmm.maxcpu: 80

Thank you, FreeBSD!
 
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