bhyve performance problem with SQL server

[Andrea Venturoli]

Hello.

I've got a FreeBSD 11.2 box running vm-bhyve with two Windows virtual 
machines, each with an instance of MS SQL server.

Everything works fine normally, but there's a specific operation which 
will impose an high CPU load on the machine and last several minutes, 
when it's expected to get the results in a few seconds.

I think I have to pass this trouble to the "programming" people, but 
before I do that, I'd like to double-check this is not a system problem.



Some notes:

_ that specific operation will put the two VMs in touch with each other, 
as one will contact the DBMS on the other and import data; however, 
that's not the only procedure which does such a thing and the others are 
working fine;

_ during the execution of such procedure, the load on the host rises, as 
both VMs show high CPU usage (in Task Manager), top shows both bhyve 
processes in kqread (but this happens all the time), disk activity 
doesn't seem so high;

_ the box has a Quad-Core CPU and I assigned two cores to each VM (I 
have hw.vmm.topology.cores_per_package=4 in /boot/loader.conf);

_ both VMs use virtio-net, with both tap interfaces connected to the 
same "virtual switch";

_ both VMs use a zvol for their HD.



Before I sentence this is an application level problem, is there some 
improvment I could do to the above? Any check or test I should run?


  bye & Thanks
	av.