Re: DP performance

[Danial Thom <danial_thom@xxxxxxxxx>]

--- Miguel Filipe <miguel.filipe@xxxxxxxxx>
wrote:
> On 4/28/05, Danial Thom <danial_thom@xxxxxxxxx>
> wrote:
> > 
> > --- Matthew Dillon
> <dillon@xxxxxxxxxxxxxxxxxxxx>
> > wrote:
> > > :No, sorry. I thought thats what you guys
> were
> > > :doing. How long do you think it will be
> before
> > > :any of the 4.x derivatives are actually
> better
> > > :than 4.x?
> > > :
> > > :Danial
> > >
> > >     Well, the main issue is that the
> original
> > > BSD code (and the
> > >     original linux code for that matter)
> was
> > > not designed to operate
> > >     in an MP environment.  Fixing it
> requires
> > > rewriting most of the
> > >     major subsystems in the kernel.
> > >
> > >     We are fairly close to being able to
> > > parallelize the protocol
> > >     stacks.  We can certainly run the
> interrupt
> > > *threads* on any
> > >     cpu, once we get the BGL turned off in
> the
> > > threads.  Directing
> > >     an actual hard interrupt to the
> appropriate
> > > cpu is harder.
> > 
> > Is there any evidence that chopping up the
> kernel
> > into threads yields a net gain with 2
> processors?
> > Linux is supposedly very good at MP, and
> linux
> > with 2 processors is still outperformed by
> > FreeBSD 4 with one.
> 
> Show me were, From what I've seen, linux kicks
> ASS in MP environments.
> with threads and with processes...
> Linux 2.6 scales better with load(see fefe's
> benchmarks) and cpus
> (linux works on a 512cpu beast, made by
> SGI...can´t imagine FreeBSD
> running on a 8< cpu machine...)
> But hey. I might be biased, and i've only
> really used OpenBSD and
> DragonFlyBSD .. but from the kernel specs of
> linux... it scales
> beastly now...

"kicks ass" is a relative term. In terms of
kernel performance, say routing packets, FreeBSD
4 with one processor beats linux with 2 by a bit.
And the trade off of that, which is what I'm
getting at here, is that LINUX sucks ass with one
processor. So in order to work well with 4
processors you have to make the OS suck with 1.
More people use 1, so you wonder what the world
will be like with the geeks in charge. You have
to make things worse for most people in order to
appease the few. At least before, you could
decide to use FreeBSD if you had a uniprocessor
system. Now there is no choice at all.

Frankly benchmarks bore me. They don't test real
world things. A machines usefulness is the sum
total of all of the things it must do to
accomplish whatever task you have it doing. A
linux 2.4 kernel will start dropping packets at
1/2 the point that FreeBSD 4 will, so I dont
really care what fefe thinks. Freebsd 5.1 was
such an unbelievable pig (and readily admitted by
its developers) that it was unusable, yet fefe
puts it right up there. Its quite humorous
really.

Danial

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