Date: Fri, 24 Oct 2014 17:14:42 +0200 From: Willem Jan Withagen <wjw@digiware.nl> To: Allan Jude <allanjude@freebsd.org>, virtualization@freebsd.org Subject: Re: Bhyve building kernel....Just an observation Message-ID: <544A6CE2.5020500@digiware.nl> In-Reply-To: <544A6A3A.2020108@freebsd.org> References: <544A083B.50007@digiware.nl> <544A6A3A.2020108@freebsd.org>
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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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