Interview with Matthew Dillon of DragonFly BSD

JigSaw writes "Well-known FreeBSD/DragonFly/Linux/Amiga system hacker Matthew Dillon discusses a number of interesting points regarding where the BSDs are going, the status and goals of his latest project DragonFly BSD, the status of his innovative Backplane distributed database, his exciting plans to develop DragonFly into a transparently cluster-capable system implementing native SSI (Single System Image) which is something that no other operating system can do today, and more."

Different threading model

[Mr. Darl McBride]

It looks like the gist of the threading model for Dragonfly is that threads all stay on one processor. I assume this is for user processes only, and that this isn't pervasive through the kernel?

For a project that gets no press

[RLiegh]

Dragonfly BSD seems to be chugging along quite nicely.

The further away they get from their 4.x FreeBSD roots, though, the more I wish they'd release an ISO. Particularly since the last ISOs for the 4 series of FreeBSD are probably going to be totally gone in a few months.

Not by a long shot.

[Tony-A]

"The reason for this excitement is that it is becoming clear to us that we can develop very clean-looking, elegant, debuggable, SMP scaleable software using this model whereas using the mutex model generally results in much less elegant (even ugly), difficult-to-debug code. Code complexity and code quality is a very important issue in any large piece of software and we believe we have hit on a model that directly addresses the issue in an SMP environment without compromising performance."

I don't really know what he's talking about, but:
If he's right, everybody wins.
Even if he's wrong and we find out why, everybody wins.
It sounds like Linux isn't hurting BSD any, and methinks for a number of reasons, Linux wouldn't be what it is today without the BSD's.

Re:Divide and conquer

[Anonymous Coward]

There is no need for BSD-from-scratch disto.

1: All the BSDs are entirely different operating systems, which are lumped into one category becuase of their roots.
2: Since no extra bullshit is thrown in like linux, there is less need for reworking the base.
3: BSD is not obscure in the least, it is rather alive and florishing.

BTW you forgot to mention Solaris, which has it's roots in BSD too.

Michael

[LittleLebowskiUrbanA]

What w/ the laziness and impatience remarks? Just can't help making a dig at anything not Debian?

Linux has no SSI?

[Anonymous Coward]

Funny, the Slashdot blurb accuses him of saying that no other system today does SSI, while according to the article he simply said their (future, potential) SSI plans will beat Linux's (present, working) SSI clustering.

Anybody have thoughts comparing the DragonFly SSI [shiningsilence.com](warning, PDF) and the Linux [sourceforge.net] one?
(Open)Mosix has had craploads of work done on it, and by the time DragonFly's is done, it will be even further ahead. I somehow doubt DragonFly's will end up being better.

PK

Re:So I looked at OpenSSI's website. ..

[Bastian]

. . . and read their brief overview at the top of the page.

And it almost made no sense to me. Those buzzwords work great one at a time, but the brain starts to make a noise kind of like the one the TV makes after the TV channel goes off the air when you string too many together at once. Especially when nothing but commas separates them.

Did anyone at HP's marketing department take an courses in English at college? Or were they just as non-clueful about what OpenSSI is when they wrote that blurb as I was when I first went to their website?

Someone should tell them Kant already has a patent on writing paragraphs that take as long to read as pages.

Re:I guess that'll show em.

[Anonymous Coward]

That's funny. One thing that drives me crazy with linux is how it is always changing.

Redhat9 binaries won't work with redhat7 and debian does things their own way. While mandrake and gentoo do it this way. Then suse jumps in and blah blah blah.

Sure they all use the same kernel but usually it is never the same kernel.

Re:I guess that'll show em.

[Rick the Red]

I think of the various Linux distros as "forks" of whatever Linus himself runs. There are literally dozens of Linux forks. Too bad Linus doesn't release a distro, so we'd know what Linux is supposed to look like. If you sit down at a Linux system you have no idea what you're going to find. From a Systems Administration standpoint alone that makes *BSD a better choice for corporations with a large number of hosts, but Linux gets all the press.

Re:Divide and conquer

[N1KO]

Even if BSDs init scripts and other base stuff is super terrific now, it won't be in 10, 20 or 100 years. Eventually one of the OSs will make changes that are incompatible with the others.

From that interview, it sounds like DragonFly is going to have a different package management system in the future. Which means either the base is going to change, you will stop calling it bsd or you will say ports isn't a basic part of bsd

Re:Something no other OS can do?

[fmayhar]

Not so much, no. The bits that were ported were never tainted and the bits that were tainted weren't ported. Because of the way we did our development, what belonged to us was never mixed with what was merely licensed. So when I said "strip out all the bits related to Unixware" I meant precisely that. Not "strip out all the Unixware bits" but strip out all the stuff in the locally-developed code that was Unixware-specific.

Of course, I was only there for the very beginning of the port; by the time the code was placed under the GPL I had been at BSDi for a while.

Backplane non-free, non-relational

[leandrod]

This SSI stuff sounds interesting, but I'd like to see his stuff compared to OpenSSI. Now the Backplane SQL DBMS seems interesting, but... First, they make the common mistake of calling SQL relational. This in itself will prevent them becoming significantly better at the logic level, which is a pity. Second, it looks very interesting as far as the backend goes. But the question here as always is, why create something from scratch? Couldn't, say, PostgreSQL, which was born on BSD anyway, be retrofitted with their stuff? Won't Oracle or IBM leapfrog them if they prove successuful? Third, looks like we have yet another BitKeeper in the making... gratis for free software, but not free itself. Makes me want to stick with PostgreSQL for now. If I wanted something proprietary, I'd go Alphora Dataphor, which at least is fully relational and not yet another SQL.

Re:Something no other OS can do?

[Anonymous Coward]

It's simply not true that "a transparently cluster-capable system implementing native SSI" is "something that no other operating system can do today."

He didn't say that, here's the paragraph from the interview (emphasis mine)..

Well I strongly believe that any project needs to have an unattainable goal, and our unattainable goal (which I hope actually winds up being attainable) is to develop DragonFly into a transparently cluster-capable system implementing native SSI (Single System Image). It is something that no non-commercial system today can do (the type of clustering Linux supports isn't even close to the type of clustering that we have as our goal, and clustering has never been one of the other BSD's goals as far as I can tell).

License contradiction?

[XaXXon]

If your application is licensed under the GPL or compatible OSI license (learn more at opensource.org) approved by Backplane, Inc., you are free and welcome to ship the Backplane open source database with your application.

followed by:

If you power an application using the Backplane database that you market or sell, or use that application to conduct any form of online commerce (selling/buying products or services over a website) you need to purchase the Backplane Commercial License.

The example given is if you run an email service from which you sell access to other companies, you must buy the commerical license.

My question is, what if the program that provides the email service is GPL. Do I have to buy a commercial license or not? One of the great things about GPL software is that if it's an internal piece of software, you can mix proprietary and GPL code as much as you want, as long as you never redistribute the program to anyone.

Also, how does dual licensing work with this? Can I license it under the GPL to myself, and then sell copies under another license to other people? Obviously THEY would have to buy a commercial license, but do I?

Just trying to point out some holes in the licensing..

Oops, just noticed the part at the end saying:
NOTE: In any of these examples, if the entire application or service is 100% GPL compatible, you may use the Backplane Free License.

But that still leaves open the question about dual licensing..

Re:I guess that'll show em.

[UID500]

Um, linux is a kernel, not a distro. the linux kernel is what "linux is supposed to look like" to linus.

Re:Different threading model

[Anonymous Coward]

The cost of moving a thread between CPUs isn't very much. A bit more than a context switch because when you context switch you might have a bit of your old data left in cache somewhere.

A big problem is sharing cachelines between CPUs, where one or more of those CPUs writes to that cacheline. This problem is second only to lock serialisation when it comes to SMP scalability.

The Linux kernel for example may move tasks between CPUs (when the task isn't running, of course). This doesn't in any way prevent the use of per-CPU data.

Also, I notice in some places (if I remember correctly), you say things like "the scheduler can be done lockless, with just a critical section". Presumably the critical section needs to be locked, right? Otherwise it isn't a critical section.

One more thing if I may. Your "token" is semantically a type of lock, correct? Do you have spinning locks at all, or are they all blocking types?

Re:I guess that'll show em.

[4b696e67]

Too bad Linus doesn't release a distro, so we'd know what Linux is supposed to look like.

If I'm not mistaken Linus has said he won't endorse or release a distro for that reason alone. Friendly competition between the distros is a good thing. It sparks invention and true innovation. Even the various *BSDs help each other out.

If you sit down at a Linux system you have no idea what you're going to find.

I disagree there. Most *nixes are fairly similar. You have a /dev directory. You have an init process. You have standard utilities such as ls, cp, grep, sed, awk, etc. I have used AIX, Solaris, FreeBSD, and Linux and they do have their differences, but they are more alike than different.

From a Systems Administration standpoint alone that makes *BSD a better choice for corporations with a large number of hosts, but Linux gets all the press.

I disagree there as well. I feel that from an administration standpoint with a large number of hosts it wouldn't matter if you were using RedHat, Gentoo, FreeBSD, OpenBSD, or any other *nix for that matter as long as the machines you were running were using the same distro. No, you wouldn't want 10 RedHat boxes, 20 OpenBSD boxes, 35 Gentoo boxes, and 15 AIX boxes. On the other hand, if you had 80 Gentoo boxes that were all kept up to date you wouldn't be any worse off than if you had 80 FreeBSD boxes (generally speaking, I know each OS has its strengths and weaknesses).

IMO the best OS to administer is the OS you know. You could have the best/most secure OS ever, but you would still get owned if you didn't know how to administer it. Hell, even the "security hole haven" Windows can be made more or less secure by a good admin.

Re:I guess that'll show em.

[Anonymous Coward]

" In the Real World, we had no two machines alike and thus needed the 1/20 ratio. And this was all the same brand of hardware and OS!"

You guys are lucky! We have 5 admins to handle over 300 machines that vary from sparcstation 5's, to V880's, to HP ProLiants, to high-end PA-RISC hardware.

You better believe we pray that we don't get called when one of the "insert product here" experts goes on vacation. And when I go on vacation, I pray nobody manages to get ahold of me !

Being seriously understaffed sucks, although it's good for job security... Until the company sinks itself.

Re: Linux has no SSI?

[Anonymous Coward]

I believe that Matt meant out of the box for one, and native for another. "Linux's" SSI is a third party package that is not exactly seamlessly integrated into the kernel, nor does it seem like it will be any time soon. Such would take the kinds of fundamental kernel alterations that are going into DragonFly, and I seriously doubt that Linus is up for that at the moment.