Bhyve building kernel....Just an observation

[Allan Jude]

On 2014-10-24 11:14, Willem Jan Withagen wrote:
> 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
> 
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> 

Doing that would give you a much more accurate benchmark.

-- 
Allan Jude

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