Subject: Re: FreeBSD Bus DMA
To: Ted Lemon <>
From: John S. Dyson <>
List: tech-kern
Date: 06/11/1998 22:02:46
Ted Lemon said:
> > > John, I've never seen any honest benchmark numbers for FreeBSD/i386
> > > vs. NetBSD/i386, much less for FreeBSD/Alpha vs. NetBSD/Alpha.   I
> > > doubt you have either, or they'd be up on your web site and you'd be
> > > pointing us to the URL.
> > >
> > I don't post benchmarks, sorry :-).
> So you're willing to make claims about FreeBSD's performance, but
> you're not willing to back them up with numbers?   Am I the only
> person to whom this seems more than a little bit disingenuous?
If I don't do all your work for you to improve your OS, it isn't
my fault. You should take it as a challenge to improve the results
of your project, just as I do mine.

> I haven't noticed a performance *problem* in NetBSD - the VM fix is an
> edge case - if your system is paging during normal use, you should add
> memory, which is shamelessly cheap right now.  In any case, now that
> you've brought this up, I fully intend to run some comparitive
> benchmarks.   I have an easy-to-swap hard drive in my laptop, so I
> think I can do a pretty credible job.   Who knows, maybe I'll be so
> impressed that I'll switch.
What VM fix are you talking about????  If you are talking about the
FreeBSD code, there is really no fix, but a rework.  If you are talking
about that silly 1second bug in the NetBSD VM code eons ago that
I helped you guys with, that wasn't even a fix.  The VM code at that
time was so far gone as to be not worth fixing, and you guys are
moving to follow that route that I knew long ago was the only real

I chose to fix the VM code, by making it work as advertised, and
you guys ended up rewriting alot of it from scratch.  So what?

Lesson:  VM code doesn't just page to/from backing store, and excessive
paging is indeed an edge condition that happens often enough to warrant
handling correctly as opposed to punting.

John                  | Never try to teach a pig to sing,     | it just makes you look stupid,         | and it irritates the pig.