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DragonFly BSD Announced
JoshRendlesham writes "Matt Dillon announced today on the freebsd-hackers mailing list the creation of the DragonFly BSD project. It seeks to build on the work of FreeBSD 4.x, including a rewrite of the packaging and distribution system, among other goals."
This is great news. God knows we need another BSD, I don't think anyone is happy that currently we only have FreeBSD, NetBSD, OpenBSD, TrustedBSD, XMach, Darwin, and Microsoft Windows.
> Brad Pitt announced a new fork from the -AC kernel tree
Rule 1: You do not talk about the -AC kernel tree.
RUle 2: You DO NOT talk about the -AC kernel tree.
Rule 3: If it's your first night in the -AC kernel tree, you HAVE to post.
...packages and ports system. They're part of the best things FreeBSD has above Linux right now!
I find this project exciting. Having tried gentoo's portage it has become clear to me that ports could be a lot better. While ports does work, it has a bunch of tools which make its use easier which arent included by default and could be integrated into ports.
"Ten years from now, they could do it in a few seconds." -- The Racketeer of the Hellfire Club, 1993, Phrack 42
-Matt
Anonymous Howard, who made a career of proclaiming the demise of the *BSD Operating Systems, was found dead at his keyboard this afternoon. He had just turned 16. An unnamed police spokeswoman said it was an apparent case of "autoerotic asphyxiation gone haywire". [You know the rest of the story.]
Having NetBSD/FreeBSD seperate was good in many ways because it kept mutually incompatable folks away from each others throats. Once things cooled down, technology began to flow in both directions between NetBSD and FreeBSD. Later on, OpenBSD came along. All sorts of good things came from that. Can you say OpenSSH?
It would be nice if DragonFlyBSD (gah, ENAMETOOLONG) was a similar deal. As a FreeBSD developer, I hope that there will be plenty of opportunities to take good stuff in both directions. If we can keep people away from each others throats and work on making the code better, then everybody wins.
Diversity is good. Developers fighting each other is bad. Forks can be a good way to relieve the stress. There is no need to make a Big Deal(TM) about it.
Insofar as performance goes, a higher version number does not mean higher performance. 4.x is a lot faster then 5.x for many types of tasks. DragonFly will be able to implement critical subsystems in MP, like the TCP stack, using an essentially mutexless design, which ultimately means that DragonFly will theoretically be able to perform better then 5.x in an MP environment once both are able to completely remove the MP lock. But that is down the road quite a bit and a lot can happen between then and now.
It's more than just replacing ports with portage, or apt-get, or some other userspace packaging system.
What they're talking about doing is having kernel support for packaging. Multiple versions of the same library could be installed with the same filename simultaneously. An application would see the correct versions of the things it needs, and it would see only the things it needs, despite what else might be installed. This is to allow for piecemeal/partial upgrades among other things.
To which I say: HALLELUJAH BROTHER!
This is exactly what I've been wanting to graft onto Linux for some time now; my latest thinking is that it could be done with a userspace filesystem (to make files visible/invisible), extended attributes (to associate the visibility contexts with application binaries), and a bit of extra process state. If the DragonFlyBSD folks make it work, it'll be intrestesting to see how this behaves from an administrative point of view.
In any case, this is not just a userspace change. This involves the kernel itself.
Another feature taken from the Amiga I/O model (for those who ever looked at the actual assembly code) is the ability to short-cut queueing operations. For example, if the target is able to execute a message synchronously regardless of what the client requested, the target can execute the message in the client's context and return a synchronous result code without even bothering to queue the message (I/O request in Amiga terminology). Likewise, if the client wants to run an operation synchronously and the target decides to run it asynchronously the target doesn't have to queue the message back to the client's reply port when it is through, it simply wakes the (blocked) client up.
To make messaging truely efficient the 'optimal' case must have the lowest possible overhead. The Amiga model serves this requirement very nicely, making optimally handled messages take no more overhead then a subroutine call would take. This is extremely important in an MP design because queueing operations often require some sort of lock and being able to avoid a queueing operation in the optimal case is simply *HUGE*.
Consider the optimal syscall path given the above. If a syscall can run without blocking your syscall 'message' winds up costing no more then a traditional syscall would. After all, there is no point asynchronizing a syscall that can run without blocking, you only have one cpu for any given userland thread anyway so you can't make things faster by switching out to handle something else and then back again. Yet in a traditional asynchronizing model like AIO, a great deal of effort and overhead is taken before you even know whether the I/O operation would block or not, making AIO expensive no matter how you cut it. The same goes with a select() based operation. And in a KSE style operation the expense occurs in having to maintain multiple kernel threads for system calls which are in-progress, instead of much smaller message structuers for system calls which are in-progress. The above Amiga-like features make it possible to encapsulate *ALL* system calls in messages, request asynchronous completion, yet still deal with synchronous completion in a manner which does not introduce a performance penalty.
That's it. I'm going to mail Daniel Robbins and ask him to make the next in his brilliant series of articles at IBM DeveloperWorks a "OS advocacy for overzealous Gentoo freaks" piece.
The first and most important bit: Always bring up Gentoo whenever ANYONE mentions ANY other operating system! This is of UTMOST importance! Just like annoying potential customers works for Internet advertisers, annoying potential users must work for OS advocates!
Longhorn would kick ass if they installed unwanted software using PORTAGE instead of Windows Update!!!!! PR0T4G3 R0XX0RZ J00R B0XX0RS!
I'm going to be burned at the stake for this, but don't worry, my karma ensures that I'll be back as a lotus blossom to annoy all you bloody geeks with pollen.
Six sick