I can answer some of these questions for you. I can't answer this, I only have successfully worked with 32-bit para- virtualized and fully-virtualized domains.
No, I couldn't find it in the FAQ or documentation. VMware uses special virtualization methods for dealing with CPU cache and memory performance degradation inherent to fully virtualized guests. Their tools include a memory management daemon that reduces overhead by freeing truly unused memory. Using ZFS with xVM makes the situation worse since it aggressively caches memory and data, similar but more extreme than how SGI XFS works. xVM fully allocates the memory, it's about the same if you didn't ran their guest tools with memory consumption. Right now they are focused on getting support for common guests, remember this is a port, and only recently has it became commercially supported by Sun. It's not viable yet because no tools exist for guests that could deal with inherent guest glitches, and the most important issues right now are networking drivers, mouse synchronization, and just simply being able to boot guests. It is not commercially ready, nor is Sun advertising that it is. Until SXDE comes with xVM, work focuses on the big issues first, the performance unfortunately is not as big of a priority since developers are already strained trying to get 64-bit para-virtualized guests, and a wide number of operating systems working under xVM. It doesn't have near-native performance, and remember VMware has been around since 1998, with thousands of engineers and direct support from cpu vendors. Guests not fully virtualized exhibit the best performance, as they translate system calls instead of running through the respective cpu virtualization extension. Windows has the worst performance because it has some architectural annoyances that make it hard to tune for, namely source code, or lack thereof. FreeBSD, NetBSD, Linux, and OpenSolaris B75+ work almost all equally well as pvms, but there are quirks for each that are needed to address, performance is acceptable for them. Linux has the best performance as a guest because it is designed to have a small fingerprint, and has had the most amount of architecture work done specific to Xen as a guest and as a host. Specific versions would be NetBSD 4, FreeBSD 7 (CURRENT), CentOS 5 and less-popular distributions like Gentoo with a Xen kernel. The Windows VNC glitch is already known, and I'm pretty sure the VNC implementation can't deal with it yet. Remember, the official VNC client from RealVNC still has its share of problems with adapting to changing resolutions, without a mirror driver (Unavailable in an installer) it can't deal with it very easily. Solaris 10 under hvm does work well, I haven't tried it, but some people I've talked with say its almost good enough to use for small porting projects between OpenSolaris and Solaris 10. I haven't seen a bug for the corruption in the installer. As for OpenSolaris, most developers are using Indiana (B75) para- virtualized, higher builds may exhibit unreported or different behavior. You should try using B75 and see if it has less issues. James On Dec 4, 2007, at 2:40 PM, Jim Klimov wrote: > Just in case the author (or further readers like me) haven't seen > the referenced thread, there's word that HVM 64-bit domains are > still underway, so for unmodified guests we must use the 32-bit > versions. > > See: > http://opensolaris.org/jive/thread.jspa?messageID=182165&tstart=0 > > BTW, can we force a 32-bit Guest domain boot (newly created or old) > with a 64-bit dom0 xVM kernel loaded and running? > > Is it in FAQ somewhere? No?.. > > Beside giving the link, I have some questions of my own, concerning > xVM performance and general compatibility: > > In my personal experience, the performance seems appalling when it's > working at all :( It's worse with the idea of a 45% RAM footprint of > Xen dom0, compared to 200-500Mb of VMWare ESX Server 3.0.1's > Console. On good big servers, 45% is a lot. > > We did some tests at work trying to install some Xen virtual > machines on Sun X4600 (snv_b77), and see if [Open]Solaris+xVM(+ZFS > +...) is a reasonable replacement right now for VMWare ESX... > > Does anyone have near-hardware performance? Maybe just a few times > worse? Which OSes and versions? For our integrations, Solaris 10, > RHEL 3-5 and Windows 2000/2003/XP are of primary interest. > > With the problems we had, I wonder: did we do something (many > things) wrong, or does everyone suffer similarly, and that's just > the way things are right now? ;) > > Here's some results of the few attempts so far (Solaris 10U4 works > well, others suck at best): > > While we did get Windows XP SP2 (32-bit) to boot and even go on > configuring in graphics mode (first reboot), it took a couple of > hours to get to the TCP/IP Settings screen (Setup will complete in > approximately 29 minutes)... BTW, VNC screen loses some part of the > display bottom side (due to unusual resolution in the Windows > installer); can it possibly adapt to VM resolution changes? > > Windows 64-bit releases failed (froze for days) in the text mode > part, Starting Windows - as expected, I see now. > > I did get a Solaris 10u4 8/07 running in a "--vnc --hvm" > installation mode, but in the text-mode installer over VNC (got a > corrupted white screen in graphical attempts). Got the full install > okay (End User + OEM packages), booted up all the way to the JDS. > Apparently it works as 32-bit, without an amd64/boot_archive and > amd64/multiboot parts yet, and seemed reasonably fast working. > > I did *not* get a guest snv_b77 running (best I did was text mode > and Signal 11 in install-solaris after Reboot Warning screen). > > > This message posted from opensolaris.org > _______________________________________________ > xen-discuss mailing list > [email protected] _______________________________________________ xen-discuss mailing list [email protected]
