I intend to soon purchase a new PC with an Intel core2duo E6750, which has the VT extensions. I am interested in using Xen / OpenSolaris build 75 as dom0, and virtualizing FreeBSD 6.2 and 7.0 as well as windows XP. However, the only specific reference to FreeBSD as a guest OS I can find is a year-old version of FreeBSD 7.0. What I would like to know is: Can I run FreeBSD 6.2 as an unmodified guest OS with OpenSolaris build 75 and the VT-extensions CPU? Another thing that is not clear to me after extensive reading: Is the performance of an unmodified guest OS using VT-extensions worse than using a paravirtualized/modified guest OS? Finally, does the dom0 OS run at full native speed or does it also suffer the ~5% performance hit since it is virtualized similarly like the domU systems? If freeBSD is not a fully supported guest OS at this time, it may preclude me from installing OpenSolaris on this computer, which would be a shame. I''m anxious to try OpenSolaris. Thanks, John This message posted from opensolaris.org
John wrote:> I intend to soon purchase a new PC with an Intel > core2duo E6750, which has the VT extensions.> I am interested in using Xen / OpenSolaris build > 75 as dom0, and virtualizing FreeBSD 6.2 and 7.0 > as well as windows XP. Make sure you get a motherboard with SATA support that OpenSolaris supports. If dom0 is running the disks in IDE emulation mode, performance is bad.> However, the only specific reference to FreeBSD as> a guest OS I can find is a year-old version of > FreeBSD 7.0. What I would like to know is: Can I > run FreeBSD 6.2 as an unmodified guest OS with > OpenSolaris build 75 and the VT-extensions CPU? NetBSD does with a little help.. See the following thread. I installed netBSD to verify this works on Solaris dom0. http://www.nabble.com/Booting-NetBSD-under-HVM-t4349412.html> Another thing that is not clear to me after extensive> reading: Is the performance of an unmodified guest > OS using VT-extensions worse than using a > paravirtualized/modified guest OS? Yes, the IO will be significantly slower... HVM guests with PV drivers (e.g. net & disk) are pretty close in performance though.> Finally, does the dom0 OS run at full native speed> or does it also suffer the ~5% performance hit since> it is virtualized similarly like the domU systems?It will run slower too.. You can choose to boot dom0 or run on metal (e.g. no hypervisor) from the grub menu though...> If freeBSD is not a fully supported guest OS at > this time, it may preclude me from installing> OpenSolaris on this computer, which would be a > shame. I''m anxious to try OpenSolaris. If you send me a pointer to the iso, I''ll give it a try.. Thanks, MRJ -- Mark Johnson <mark.johnson@sun.com> Sun Microsystems, Inc. (781) 442-0869
> However, the only specific reference to FreeBSD as a > guest OS I can find is a year-old version of FreeBSD > 7.0. What I would like to know is: Can I run FreeBSD > 6.2 as an unmodified guest OS with OpenSolaris build > 75 and the VT-extensions CPU?Can''t comment on a FreeBSD 6.2 HVM domU running on OpenSolaris build 75 and Intel VT CPUs, but when using an AMD64 X2 CPU, it works just fine (with the execption of the frequent dom0 hangs on dual core cpus when a domU consumes 100% cpu time[*]). Unlike NetBSD 3.1, FreeBSD 6.2 doesn''t seem to have a problem with the floppy controller. [*] Bug 6612343 http://bugs.opensolaris.org/bugdatabase/view_bug.do?bug_id=6612343> Another thing that is not clear to me after extensive > reading: Is the performance of an unmodified guest OS > using VT-extensions worse than using a > paravirtualized/modified guest OS?Yes. Disk and network performance should be worse in a HVM domU, when compared to a PV domU.> Finally, does the dom0 OS run at full native speed or > does it also suffer the ~5% performance hit since it > is virtualized similarly like the domU systems?There is a performance hit for dom0, too. Today, an opensolaris snv_76 nightly build from sources in a dom0 needed 1 hour 50 minutes. AFAIR, on bare metal a full nightly compilation needs ~ 1 hour 15 minutes. That would be almost 50% slower. This message posted from opensolaris.org
john wrote:> Thanks, Mark! > I looked, but I could not find a list of supported hardware on the > OpenSolaris site. The motherboard listed on the estimate is "ASUS P5K > INTEL P35 ATX". It comes with a 250GB SATA II drive.Looks like this has an Intel ICH9 chipset. The BIOS has to support putting this in AHCI mode. I had an ASUS motherboard with ICH8 which did not let you do that even though the chipset supported it. I have a motherboard with a ICH9R (in AHCI mode) which works fine with the AHCI sata driver. So I assume the ICH9 will work just as well.> I''ve read that FreeBSD is problematic. The official FreeBSD handbook > does talk about Xen on a Linux Dom0, but only for the upcoming FreeBSD > 7.0: > http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/virtualization-guest.html > > Since it doesn''t say otherwise, I assume that means FreeBSD 7.0 supports > paravirtualization.It does not support PAE mode. I had it running in PV a long time ago.. But every has switched to PAE mode so they can support 32-bit PV domains on a 64-bit dom0 (in Xen 3.1). FreeBSD didn''t support PAE mode the last time I looked.> > Here is the link to the latest official version 6.2: > ftp://ftp.freebsd.org/pub/FreeBSD/releases/i386/ISO-IMAGES/6.2/I''ll give it a try on my Intel box.. MRJ> Your info is a big help. I see Juergen has also responded in the forums > and his answers completely agree with yours. > John-- Mark Johnson <mark.johnson@sun.com> Sun Microsystems, Inc. (781) 442-0869
I didn''t expect the performance impact to the dom0 system to be so substantial, wow. I''ve done some more research, I found Xen''s roadmap here: http://wiki.xensource.com/xenwiki/XenRoadMap And I''ve found a good slide presentation (4MB PDF) from Xen here: http://www.linuxtag.org/2007/fileadmin/linuxtag/downloads/besucher/slides/LinuxTag2007-slides_Virtualisation_Xen-TNG_Hand.pdf They indicate a lot of improvement for the HVM is coming and specifically address the IO and memory bottlenecks, and well as the possibility of paravirtualized drivers for unmodified OSs. So now I''m wondering: would it make more sense to wait for Xen to mature and in the meantime run FreeBSD inside KQemu (or vice versa). It seems Xen uses Qemu anyway to emulate these IO devices in the HVM systems, so it follows that the performance would be comparable to Xen, but you wouldn''t severely strap the performance of your "host OS". Is that fair to say? Is running on KQemu about the same performance-wise as an HVM DomU on Xen? This message posted from opensolaris.org
john wrote:> > Here is the link to the latest official version 6.2: > ftp://ftp.freebsd.org/pub/FreeBSD/releases/i386/ISO-IMAGES/6.2/If tried the iso, as Juergen says, it works fine on a amd system with HVM support. It does *not* work on an intel system though... There''s a bug there that we''ll have to chase down. They way that realmode emulation works is different between the to HVM architectures.. MRJ -- Mark Johnson <mark.johnson@sun.com> Sun Microsystems, Inc. (781) 442-0869