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To: terry@cs.weber.edu (Terry Lambert)
Cc: mycroft@ai.mit.edu (Charles M. Hannum), hackers@FreeBSD.org
Subject: Re: benchmark hell.. 
In-reply-to: Your message of "Tue, 25 Apr 95 12:08:44 MDT."
             <9504251808.AA00479@cs.weber.edu> 
Date: Tue, 25 Apr 95 12:50:59 -0700
From: Bakul Shah <bakul@netcom.com>
Sender: hackers-owner@FreeBSD.org
Precedence: bulk

> Part of my campaign to refuse to acknowledge factions in the BSD camp.
> You'll also notice a studious lack of "we", "us", "they", "our", and
> "them" when discussing relative issues.

Nice to know there is atleast one other person who has his
head in the sand (err.. feels the same way) as I do in this
regard.  No smiley though.

> The idea here is that by default, processes are assumed to not use the
> FPU, and thus by default the FPU trap results in code fixup rather than
> FPU operations.  Thus it does not matter which FPU operation is used
> first.

Isn't it easier to just assume that everyone may
_eventually_ use FP and simply initialize the FP state on
exec?  If they never use FP there is no loss.  One time
initialization hit is not worth worrying about.  There are
no FPU operations involved (you just copy the initial state
from somewhere and set the `stale' bit).

Charles writes:
> (With a slight kluge, it may be possible to combine this with the
> check for whether you're using the emulator or not, and eliminate the
> extra bit altogether.  I'll have to try this.)

This can even be considered a `cleaner" solution!  When
someone else is using the FPU, _you_ don't have it!  So your
choices are to either take it away from this someone else or
emulate!!  Emulation may even be cheaper than save/restore
of FPU state for some simple FP operation (once or twice)!
Though, probably not worth microoptimizing like this.

I will pass on the page protection discussion :-)

--bakul