FreeBSD 7, DragonFly's status

Steve O'Hara-Smith steve at
Thu Feb 28 04:07:27 PST 2008

On Thu, 28 Feb 2008 21:53:36 +1100
"Dmitri Nikulin" <dnikulin at> wrote:

> On Thu, Feb 28, 2008 at 4:09 PM, Justin C. Sherrill
> <justin at> wrote:
> > On Wed, February 27, 2008 11:29 pm, Dmitri Nikulin wrote:
> >
> >  > The benchmark at
> >  > (for the full presentation, see
> >  >, that plot is on slide
> >  > 17) indicates that FreeBSD 7 not only competes strongly with current
> >  > Linux performance and scalability, but that DragonFly has been beaten
> >  > even by NetBSD which came late to the SMP party.
> >
> >  Minor quibble: you're pointing at benchmarks on an 8-core xeon.
> >  Relatively uncommon hardware, though I'm sure that'll change within a
> > year or so.
> Sure, but SMP scalability is one of the key goals of DragonFly, and
> for it to be beaten by NetBSD (for which this is not a major goal, and
> for which SMP scalability only started being worked on a year ago) is
> very confusing. I haven't seen it compared with 1.12, but since no
> huge scalability work has gone in for a long time, I doubt it would
> close the gap much.

	AIUI not using the approach to SMP that FreeBSD used was a major
factor in starting DragonFly on the basis that it hurts single proceesor
performance and is inelegant. 

	I'm sure the DragonFly team would welcome a developer determined to
push the BGL steadily further inwards until it vanishes. We would then all
find out if the DragonFly approach to SMP really is the best. Until that
work is done there is no real way of telling.

> So while DragonFly has a lot going for it
> (which I never denied), it's challenging to find a situation for which
> DragonFly is actually a better choice than FreeBSD.

	I really like the continuous rewindable backups I get from the
journal system in DragonFly, AFAIK that's still unique to DragonFly. I look
forward to better ones with Hammer. All my boxes are uniprocessor so SMP
performance really doesn't matter at all to me, but losing data does :)

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