Why did you choose DragonFly?

[Oliver Fromme]

Samuel J. Greear <sjg at evilcode.net> wrote:
 > What has drawn you to use the DragonFly BSD operating system and/or
 > participate in its development by following this list? Technical
 > features, methodologies, something about the community?

First of all, I'm a FreeBSD user (since 2.0.5), and I'm not
using DragonFly BSD for production.  However, I installed
it in a qemu instance for "playing" because I'm interested
in it from a technical point of view.

When DragonFly BSD forked from FreeBSD in the 4.x days, I
was fascinated by Matt's announcement and the declaration
of goals, in particular his SSI "vision".  At that time, I
thought that a working SSI cluster based on BSD technologies
would be the coolest thing on earth.  So I subscribed to
the DF mailing lists (or rather, to the NNTP groups) and
started to "watch the game".

Another incentive was Matt's plan to implement a message-
passing system inside the kernel, similar to what is used
in AmigaOS.  Having an Amiga background myself -- just like
Matt -- I found this very interesting.  I was curious how
it would work out.

Over the years, DragonFly BSD grew several features that
were not present in FreeBSD, and which I found useful or
interesting, such as variant symlinks (I still miss them
very much in FreeBSD), process checkpointing (extremely
cool, but needs some improvement to make it work better
in practice), UFS journal streams, swapcache, and of course
vkernel and HAMMER.

Today I think that the SSI goal has become less important.
The "cluster hype" has diminished and been partially
replaced by the "cloud hype".  Today, it is extremely
important to have excellent SMP scalability.  Multi-core
systems are common, my desktop at home is a 6-core AMD
Phenom II X6 which costs less than 200 Euros.  You can
buy x86 machines with 4 CPU sockets, 8 cores each, plus
hyperthreading, so you get a 64-way SMP system.  I think
DragonFly BSD doesn't support these (yet), but don't worry,
FreeBSD doesn't either.  ;-)  (They just upped the limit
to 32-way in 9-current.)  Oracle/Sun introduced a 128-way
Sparc processor last week (16 cores with 8 threads each),
and you can put 4 of those into a system ...

The trend is obvious:  Increasing the CPU clockrates is
getting more and more difficult, so the engineers start
to increase the number of cores.  Software has to keep up
with the hardware development, and that's especially true
for operating systems.  FreeBSD and DragonFly BSD have
chosen somewhat different routes towards improving SMP
scalability, but I think they are both successful.  Given
the apparent fact that DF seems to achieve similar speed
with much lower complexity, I'm even tempted to say that
DF is more successful than FreeBSD in this regard ...  But
I'm a FreeBSD committer, so I'm not allowed to actually
say that.  ;-)  (Just kidding.)

Best regards
   Oliver

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Oliver Fromme, secnetix GmbH & Co. KG, Marktplatz 29, 85567 Grafing b. M.
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