From owner-freebsd-hackers  Wed Apr  3 13: 0:39 2002
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Date: Wed, 3 Apr 2002 12:42:21 -0800 (PST)
From: Julian Elischer <julian@elischer.org>
To: Mike Silbersack <silby@silby.com>
Cc: John Regehr <regehr@cs.utah.edu>, freebsd-hackers@FreeBSD.ORG
Subject: Re: Linuxthreads on Linux vs FreeBSD performance question
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On Wed, 3 Apr 2002, Mike Silbersack wrote:

> 
> On Wed, 3 Apr 2002, John Regehr wrote:
> 
> > Anyway, I was speculating that the higher cost is either due to (1) a
> > failure, in FreeBSD, to avoid page table operations when switching
> > between threads in the same addres space, or (2) some other kind of
> > semantic mismatch between Linuxthreads and rfork.  Is one of these
> > guesses right?
> >
> > Any help appreciated.  Thanks,
> >
> > John Regehr
> 
> You may be able to learn which is the case by building a kernel with
> profiling support and seeing where the hotspot is during your tests.
> 
> Offhand, I'd guess that any of your ideas is possible.  I don't believe
> that much time was spent optimizing the kernel for Linuxthreads.
> 
> Have you tried benchmarking process to process context switch times to see
> if the results are similar?

Also:
You should run both linuxthreads binaries compile on linux (using
emulation) and compiled on FreeBSD.  it would be interesting to see
if there is a difference..







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