Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!nrl-cmf!ames!oliveb!3comvax!bridge2!auspex!guy
From: guy@auspex.UUCP (Guy Harris)
Newsgroups: comp.arch
Subject: Re: RISC v. CISC (really, context-switching & windows)
Message-ID: <313@auspex.UUCP>
Date: 27 Oct 88 16:43:33 GMT
References: <156@gloom.UUCP> <310@lynx.zyx.SE> <332@pvab.UUCP> <15964@agate.BERKELEY.EDU> <23367@amdcad.AMD.COM> <16003@agate.BERKELEY.EDU> <6996@winchester.mips.COM>
Reply-To: guy@auspex.UUCP (Guy Harris)
Organization: Auspex Systems, Santa Clara
Lines: 13

>	Register window design (as in UCB) used certain kinds of programs
>	to create the statistics to support the design. User programs
>	often bounce around in a fairly shallow window-count.
>	UNIX kernels are worse.  They often zoom up and down 10-12 levels
>	very quickly, causing window faults like crazy.  I have to believe
>	the SunOS folks have been working hard to tune for this.

While I was at Sun, I don't remember there ever having been any effort
to reduce the depth of the kernel call stack in order to speed things up
on SPARC-based Suns.  (Remember, they have to make it run sufficiently
fast on three architectures, not one - four, if you count 370/XA and
compatibles, and even more, if you consider that a lot of Sun code is
going into S5R4....)