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From: Julian Elischer <julian@ref.tfs.com>
Message-Id: <199504250650.XAA05638@ref.tfs.com>
Subject: Re: benchmark hell..
To: bde@zeta.org.au (Bruce Evans)
Date: Mon, 24 Apr 1995 23:50:04 -0700 (PDT)
Cc: terry@cs.weber.edu, toor@jsdinc.root.com,
        geli.com!rcarter@implode.root.com, hackers@FreeBSD.org,
        jkh@violet.berkeley.edu
In-Reply-To: <199504250440.OAA15562@godzilla.zeta.org.au> from "Bruce Evans" at Apr 25, 95 02:40:21 pm
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> FreeBSD's low level context switching is faster than Linux's because
> hardware tasking is not used.  Perhaps there is a lot more bloat in
> other layers of the context switching.  (Yes, there is.  E.g., calling
> microtime() for each context switch is very expensive except on
> Pentiums).  microtime() has to be called so that FreeBSD can do better
> timing statistics and scheduling than Linux.  ) However, for real
> processes, context switching is relatively rare, so small differences
> (less than a factor of 2-10) in the speed of context switching don't
> matter.
Bill Jolitz actually recanted on this..
in 386BSD, he as used the LINUX scheme of the 386 built-in
context switches....
he eventually decided the advantages outweighed the disadvantages..
I believe he decided that, in the big picture, the CISC operation was faster
than the "do-it-yourself" version.

> 
julian