Bhyve building kernel....Just an observation

[Willem Jan Withagen]

On 24-10-2014 17:03, Allan Jude wrote:
> On 2014-10-24 04:05, Willem Jan Withagen wrote:
>> Hi,
>>
>> Just out of curiosity I did the following:
>>
>> Updated 10-STABLE src in both Dom0 and in the Bhyve FreeBSD VM
>> Rebooted my bhyve AMD testing machine so it was in a fresh state.
>> Nothing special loaded orhter than ZFS.
>>
>> And build a 10-STABLE kernel on the raw box, that took about 6 minutes.
>> no {make,src}.conf, so the full GENERIC KERNEL
>> That took about 6:45 minutes.
>>
>> Again rebooted to clean the box up.
>> And then booted a 10-STABLE bhyve VM with all memory and processors
>> assigned to the VM. So all the power could be available to the VM.
>>
>> The build again 10-STABLE in the VM.
>> That took about 9:30 minutes.
>>
>> Now it looks like the VM has a 50% overhead.
>> My expectations were quite a bit better for the performance difference
>> between the two?
>>
>> Would people with more experience in doing VM stuff expect such a large
>> difference?
>> Or is this a to be expected result?
>>
>> Thanx,
>> --WjW
>>
>> System info:
>> Dom0:
>>     11.0-CURRENT FreeBSD 11.0-CURRENT #1 r273066M
>>     (110.0 Head with Neel's patch)
>>     CPU: AMD Phenom(tm) II X6 1075T Processor (3013.83-MHz K8-class
>>     16 Gb Ram
>>     ZFS mirror
>>         2* 500Gb WD WD5000AA
>>         cache 2* Samsung SSD 840 PRO Series DXM05B0Q
>>
>> Dom Bhyve
>>     FreeBSD 10.0-RELEASE-p9
>>     ahci-hd 16GB

> The big difference here is probably disk performance. If you do
> something that is pure CPU, you'll usually get about the same
> performance as the host, but virtualized disk is not always nearly as good.

Would it make any difference to use virtio instead of ahci-hd?

In any case, to test your assumption:
	build a 10G memdisk in Dom0 and DomU
	load it with sources and /usr/obj
and see if that helps getting things closer?

Nice thing to do during eveninghours in the weekend.

--WjW