Solaris: the awesomest virtualization ever?

There's an advocacy piece, in Forbes of all places, that offers a pretty unbalanced perspective on Solaris. (I hesitate to even link to it, because it feels like sensationalism just to generate huge numbers of outraged readers.) The author, Dan Woods, doesn't mention any negative points to Solaris at all, which should raise the suspicions of any reader with critical thinking skills, but I wanted to debunk some of the virtualization statements in particular:

Dan claims that Linux virtualization is the result of un-coordinated development from a number of companies, and Solaris virtualization is better because it's engineered "top to bottom" at a single company. Seamless integration can certainly offer advantages (see Apple), but I take issue with both his observations about the ecosystem and the conclusions he draws from them.

Aside from containers, Solaris uses hypervisors from Xen (marketed as xVM), and VirtualBox (from the innotek acquisition). Neither of those solutions were designed for Solaris; they were adopted years later to fill gaps in Sun's offerings. However, they are currently developed by Sun, so you still have the "single company" argument. About that...

Where I come from, being completely dependent on a single company is a bad thing, and I'm not even talking about the freedom of open source. It's called "vendor lock-in," and it's bad because there's no competition and customers are at the mercy of that single company's roadmap. Companies invest lots of money developing and supporting 3rd party ecosystems because it's a critically important to their customers. Anyways, looking at it from another angle, isn't it disturbing that virtualization ISVs don't consider Solaris important enough to target? Sun had to buy them outright or develop solutions in-house.

Dan claims Solaris containers cause a 2% performance degradation, vs. "about 20% for a hypervisor." While it's true that Forbes isn't a good forum for presenting performance analyses, without even a hint about where they came from, offering these numbers is ridiculous. It's often true that you can pick a specific benchmark and environment to support any argument, but Dan didn't even pretend.

Finally, I thought Dan's most interesting claim was the one for which he didn't offer any supporting arguments at all: that Solaris is now safe. Even if he's right, and Solaris is indeed the most awesome OS ever seen, that still doesn't guarantee it a slot on the Oracle roadmap.

Wind River Hypervisor release

Yesterday Wind River Systems released the hypervisor they announced last summer, complete with YouTube videos:

• Release announcement
• Mark Hermeling's blog entry
  
• LinuxDevices coverage
• EETimes coverage

Things I find interesting:

• From the demo video, we can see that the x86 port uses VT, but the PowerPC core doesn't have equivalent functionality (e500v2 is pre-ISA 2.06). That must mean they've got a paravirtual interface, likely the "virtual board interface" mentioned.
• EETimes quote: "We map I/O into the guest environment directly so it can directly talk to data registers to get higher performance." Given that they're releasing VxWorks MILS Platform 2.0 today for the hypervisor, which presumably requires high levels of isolation, I'm willing to bet that direct IO access is an option rather than a design assumption.
  
• Mark's demo videos had an emphasis on their Workbench IDE. I don't know if this was a conscious decision or not, but it does nicely reinforce the notion of the hypervisor as part of a solution, not a standalone product.
• They advertise their "MIPC" shared-memory inter-guest communication mechansim. I hope they just put a fancy name on virtio, but I doubt it. If they aren't using virtio, they're developing yet another set of virtual IO drivers for Linux. :(
• Their Linux patch isn't mentioned, but I hope they will be publishing it and merging it upstream, instead of the usual RTOS vendor approach to Linux...
• They consistently advertise the performance impact as "2-3% at worst." That's a nice marketing bullet, but is never the right answer to a vague performance question. The right answer is "it depends." In this case, it depends on the processor model, the workload, the partitioning configuration, and more. For example, VT-enabled x86 virtualization will have very different performance characteristics than paravirtualized PowerPC.

All in all, it's a significant event when a dominant embedded software company enters a new area like virtualization. As time goes by, it will be interesting to see how well they play with competitors' software... who is going to port Integrity to the Wind River virtual board interface? ;)