The NetBSD Foundation has published a press release reporting on the benefits of the NetBSD/xen port, initially committed by Christian Limpach as previously reported. Since then, much progress has been made, and the NetBSD Project is now using NetBSD/xen internally. See the press release for further details.
NetBSD and Xen
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Eugenia Loli
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So to run on many platforms it aims to run on one platform? Interesting.
What are the differences between xen2 and xen? I read in their mailing list NetBSD was working to get a xen2 port soon.
I am using a Virtual Private Server (VPS) hosting provider that uses Xen to segment the hardware of one server into many virtual servers. It is amazing. My VPS feels like it runs at the full speed of the host CPU (benchmarks show that it does!) but with a limit on memory. Xen seems to allow guaranteed CPU units with bursting but memory allocation is non bursting.
The VPS provider will be adding NetBSD Xen hosting if there is demand but they are really waiting until Xen makes its way over to FreeBSD. That should happen soon.
If you have tried virtualization like VirtualPC, VMWare, Virtuozzo or User Mode Linux then you will not believe how fast Xen flies until you try it. Xen multiplexes your hardware and takes almost no overhead. When I say almost no overhead I mean 1% to 2% (my feeling, not a measurement). It is a very, very, very, itsy-bitsy, tiny-weeny, slightly small amount of overhead.
BTW, Any company that invested in older virtualization technology (i.e. Microsoft with VirtualPC) got ripped off bad. Yes, Xen does take a kernel mode but Windows is not exclued from apply such mods. If Microsoft had wanted to they could have Xen support now. In fact, they already funded the research and developed the kernel mods. Why oh why are they releasing their Virtual Server Edition based on VirtualPC? VMWare and VirtualPC are completely dog slow compared to Xen. Yes, Xen is that good.
Your gut estimate is pretty close to the mark … See http://www.cl.cam.ac.uk/Research/SRG/netos/xen/performance.html
Unlike the other products, they consistently run between 98% and 90% of ‘full speed’. For computiaonally instensive work,it seems to be closer to 98%, for transactionally intensive work, (which I assume has more disk I/O) this drops to 90%. Pretty amazing stuff 🙂
i’m a little confused by the architecture? is this right?…
Xen runs on x86.
Xen hosts multiple guest OSes. one of these OSes is a “master” or “controller” .. and because this special one needs to do more – currently only linux 2.4, 2.6 and netbsd 2.0 can be the domain-0 guest OSes.
is that right? the user-manual seems to indicate that you instead add xen functionality to your existing linux/netbsd installation.
I’m not sure that you can run a NetBSD-only Xen system. I’ve been reading the Xen-devel list for awhile. From the seems of it, you install your preferred Linux (Fedora and Debian seem to be favorites), and then install a Xen-ized kernel. You reboot, and this is your master. From here, you launch other images running kernels of arch ‘Xen’. You can run Linux, of course, NetBSD, and to a certain degree, FreeBSD.
You can get FreeBSD images from:
http://www.fsmware.com/xenofreebsd/5.3/
but from the list, it wouldn’t seen this is production quality.
I guess the benchmark at “http://www.cl.cam.ac.uk/Research/SRG/netos/xen/performance.html“ is performed on an x86 computer. I wonder how the performance loss of xen is under different architectures like IA-64 or xScale or PowerPC… Any references?
Xen does *not* emulate hardware, but instead multiplexes access to the x86 hardware you have. That means that Xen will not run native on another architecture.
Comparing speeds, you have this gradient:
VirtualPC running on a PowerPC – slow because all hardware is emulated.
VirtualPC or VMWare running on an Intel P4 – medium because all hardware is still emulated and priveledged instructions are intercepted. Non priveledged instructions may run without interruption pending scheduler priority.
Xen – fast because no hardware is emulated. Only priveledged CPU instructions are intercepted and handled in a special way to multiplex.
There are most likely other differences, but that’s all I gather at this hour.
Karrick
Hmm I thought xen was just a virtualization architecture like the JVM and any processor could emulate xen therefore run a NetBSD/xen in xen bytecode.
Otherwise I don’t see why this is cool. It’s x86 specific.
Fedora core 4 will come with the xen 2 port and full integration with the installer.
Nice press release. But, I can’t find a howto anywahere that tells me how I can install Xen on a NetBSD (or FreeBSD) only setup. I have nothing against Linux, it’s just that I’m much more familar with FreeBSD and NetBSD.
It probably doesn’t exist yet (it’s only a first implement), but I’d be surprised if it didn’t eventually exist given that the Linux implementation is open for inspection.
I’m guessing the one wringle in writing one is that Xen is GPLed. I don’t know who tightly coupled Xen is to the host OS, but if it is tightly coupled, the host NetBSD might have be be covered under the GPL.
The FreeBSD port works just fine. My company has a couple developers doing kernel module work with it.
Neither FreeBSD nor NetBSD runs in Domain 0 currently.
It may be now, but with IBM throwing money at it and their new Power5 processor damn near perfect for it, Xen won’t be x86 only for long.
Xen’s purpose is to allow isolated, high-performance virtual machines on the architectures it runs on – it doesn’t allow simulation of foreign architectures.
High performance virtualisation is very difficult on x86, so it uses kernel mods to avoid some of the usual stumbling blocks.
You can run virtual machines with very low performance hit. Linux 2.4 / 2.6, NetBSD, FreeBSD and Plan 9 are currently available, others will follow.
Xen runs on x86 now at production quality. A Xen port to x86_64 is in development and progressing well. Xen is also being ported to IA64 and PowerPC.
Nice press release. But, I can’t find a howto anywahere that tells me how I can install Xen on a NetBSD (or FreeBSD) only setup. I have nothing against Linux, it’s just that I’m much more familar with FreeBSD and NetBSD.
http://mail-index.netbsd.org/port-xen/2005/03/13/0000.html