From owner-freebsd-arch  Sat May 20 10:43:14 2000
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Date: Sat, 20 May 2000 10:42:48 -0700
From: Arun Sharma <adsharma@sharmas.dhs.org>
To: Wes Peters <wes@softweyr.com>
Cc: arch@FreeBSD.ORG
Subject: Re: Sparc & api for asynchronous task execution (2)
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In-Reply-To: <3924DA18.392990EA@softweyr.com>; from Wes Peters on Fri, May 19, 2000 at 12:07:20AM -0600
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On Fri, May 19, 2000 at 12:07:20AM -0600, Wes Peters wrote:
> > >       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.

Times have changed.  If you have looked at stack traces in Mozilla or
Konqueror, they easily go 40 calls deep.

The real problem with sparc register windows is flushing of the stack
on every system call. Clever software tricks can avoid this on IA-64.

	-Arun


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