Saturday May 21, 2005

Open Solaris is Good for Linux!

Open Solaris is Good for Linux!

There is quite a lot of discussion of various reasons and motivations for Sun to open source its crown jewel - the Solaris operating system. Quite a few people, both internally at Sun and externally believe that the move will help Sun as a company, but here I'd like to explore why opening Solaris is good for everyone else - for Linux for FreeBSD and for the computer community, in general.

In my opinion, the real value of the OpenSolaris is the opening of a vast amount of knowledge about the design of very complex computer systems. To really appreciate the value of this knowledge it helps to think about the way humans learn and understand the meaning of things.

The following quote is from the paper by Marvin Minsky:

Castles In The Air.

The secret of what something means lies in the ways that it connects to all the other things we know. The more such links, the more a thing will mean to us. The joke comes when someone looks for the "real" meaning of anything. For, if something had just one meaning, that is, if it were only connected to just one other thing, then it wold scarcely "mean" at all!

That's why I think we shouldn't program our machines that way, with clear and simple logic definitions. A machine programmed that way might never "really" understand anything -- any more than a person would. Rich, multiply-connected networks provide enough different ways to use knowledge that when one way doesn't work, you can try to figure out why. When there are many meanings in a network, you can turn things around in your mind and look at them from different perspectives; when you get stuck, you can try another view. That's what we mean by thinking!

That's why I dislike logic, and prefer to work with webs of circular definitions. Each gives meaning to the rest. There's nothing wrong with liking several different tunes, each one the more because it contrasts with the others. There's nothing wrong with ropes - or knots, or woven cloth - in which each strand helps hold the other strands together - or apart! There's nothing very wrong, in this strange sense, with having all one's mind a castle in the air!

To summarize: of course no computer could understand anything real -- or even what a number is - if forced to single ways to deal with them. But neither could a child or philosopher. So such concerns are not about computers at all, but about our foolish quest for meanings that stand by themselves, outside any context. Our questions about thinking machines should really be questions about our own minds.

In Minsky terminology, Solaris source is an extremely rich body of interwoven knowledge about the design of the state of the art computer systems. This body of knowledge was produced (and packed in the form of C code) in the course of many years of Solaris development by many extremely competent engineers. For a long time this knowledge was only available only to the small community of engineers and soon it will be available to everyone curious enough to tap it.

I am not suggesting that the knowledge embedded in other operating systems source code is any "better" or "worse" than the one embedded in the Solaris code. It was created by different people having different background, different objectives, different environments and different customer bases. It is just different. And, together, all of these provide even richer web of knowledge, that is much more useful then each individual part because they represent quite different dimensions.

So why is opening up a bunch of source code is really important to Linux (or FreeBSD, or any other software project)? Because, someone who takes the time and effort to read and understand even small parts of this embedded knowledge will almost certainly get new insights in whatever projects he or she is currently working on or thinking about. Even if the developer will not reuse any single line of the code, he will, definitely, gain in understanding his own area of expertise. Not to mention the trivial fact that the CDDL license allows developers to directly build their software based on the Solaris source. Consider, for example, an "open-sourcing" of a small part of Solaris design - the Slab Allocator, made by Jeff Bonwick in the form of the USENIX Paper and the followup paper. Was it useful to Linux and other software projects? If we ignore that fact that the slab allocator based on these papers is now the standard Linux kernel memory allocator, I am pretty sure that just reading these two papers was a very useful journey for a reader. And, be assured that the person who invented the Slab Allocator has more to say - and, indeed, says a lot - in C.

Another, more recent, example is DTrace, which is already available. It is not immediately obvious why DTrace is good for Linux, consider how much more effort is now put in creating the adequate Linux tracing facility that could compete with DTrace! Even if not a single line of DTrace source will find its way into the Linux distribution, it would definitely serve as a "prove of existence" and an inspiration. And, as Linux tracing facility will improve under the influence of DTrace, DTrace itself will improve to stay a relevant tool.

As a result of such cross-influence of ideas, the whole body of available software improves in its quality and the coverage and everyone wins!

And for this reason it makes sense for many computer engineers, students and just curious minds around to set aside some time to read and understand some parts of the OpenSolaris source code. And those who think that something embeds the whole meaning should, probably, reread the Minsky paper.

Technorati Tags: OpenSolaris, Solaris.