Date: Sun, 21 May 2000 15:20:32 -0600 From: Wes Peters <wes@softweyr.com> To: Terry Lambert <tlambert@primenet.com> Cc: Chuck Paterson <cp@bsdi.com>, Doug Rabson <dfr@nlsystems.com>, arch@FreeBSD.ORG Subject: Re: Sparc & api for asynchronous task execution (2) Message-ID: <39285320.B1DD9837@softweyr.com> References: <200005191744.KAA00232@usr02.primenet.com>
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Terry Lambert wrote:
>
> > Terry Lambert wrote:
> > >
> > > > }I didn't realize that every function call involved a fault on the sparc
> > > > }architecture - that sounds pretty nasty.
> > > >
> > > > Actually every function call doesn't cause a fault, every
> > > > time you overflow/underflow the current set of register windows causes a
> > > > fault. (Perhaps what you meant). This means that calling a function
> > > > from the bottom most function will cause two faults, one for going down
> > > > and one eventually as you go up.
> > > >
> > > > This makes going up and down when you don't overflow
> > > > very fast at the expense of when you add to the total depth.
> >
> > The register window sizes weren't picked willy-nilly. The SPARC default
> > size is 7 windows, chosen after months of analyzing every M68K SunOS
> > program they could get their hands, including compiled C, Pascal, LISP,
> > and Fortran programs.
> >
> > I suspect C++ and Java probably skew these stats a little. This might
> > account for the 8 windows in more modern SPARC processors.
>
> Please watch your attributions; I said none of this.
Precisely where did you get the idea I was accusing you of anything?
I was merely adding to your assertion that the register window system
was carefully designed as an optimization, not as the foolishness the
original questioner seemed to think.
Calling into question those who are supporting your arguments isn't a
great way to enforce your point.
--
"Where am I, and what am I doing in this handbasket?"
Wes Peters Softweyr LLC
wes@softweyr.com http://softweyr.com/
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