Path: utzoo!mnetor!uunet!lll-winken!lll-lcc!pyramid!prls!mips!mash
From: mash@mips.COM (John Mashey)
Newsgroups: comp.arch
Subject: Re: Longer quote, RPM-40 performance
Message-ID: <1731@winchester.mips.COM>
Date: 1 Mar 88 09:25:23 GMT
References: <9689@steinmetz.steinmetz.UUCP> <9732@steinmetz.steinmetz.UUCP>
Reply-To: mash@winchester.UUCP (John Mashey)
Organization: MIPS Computer Systems, Sunnyvale, CA
Lines: 48
Keywords: DAIS, 14 MIPS, General Electric

In article <9732@steinmetz.steinmetz.UUCP> sunset!oconnor@steinmetz.UUCP writes:
>
>Uh, gee, I don't know. Seems to me it has everything it needs to
>support UNIX. It supports page faults, has a secure (we hope)
>supervisor mode, some built-in address space management, a 8 gigabyte
>total address space, software traps ... gee, just about everything a
>68010 has, even vectored interupts. What specifically does it lack
>that indicates it wasn't built for UNIX ?

I didn't really mean to fire up an argument, because I thought I was
agreeing with what people said it was.
But, if people want to claim that it's a good UNIX engine,
it would be nice to know:
	a) How you use the MMU to do a modern UNIX?
	b) How you turn the SRAM into a cache, because NOBODY cares about
	a workstation whose memory is limited to the size of SRAM you
	can drive off the CPU? (and what the performance hit is?)
	c) How much of a performance hit one takes from the various
	design choices when trying to use it in the general environment?
	d) Any benchmark numbers at all, for real programs of substance,
	even run on simulators?  Can't we EVER get some real numbers?

>What it wasn't was OPTIMIZED for UNIX. It's OPTIMIZED for the embedded
>computing environment. You know, like BM/CCC and cruise missiles.
>Like AEGIS, SUBACS, Star Wars, and that stuff. Not trivial, you bet.
>Calling it a microcontroller, well, that seems kind unfair.

Nobody thinks of these as trivial applications.  "Microcontroller"
was not meant as a pejorative, rather as distinguishing it from
micros aimed more at more general-purpose environments.  Suggest
another term; I think microcontrollers are fairly smart these days.

>It may not be able to run UNIX as fast as another 40MIPS machine that
>was more UNIX-oriented, true. :-)  But the minimum functionality to
>support a multi-tasking operating system is there. Mainly because we
>think that the embedded world may head this way. Someday. When Ada
>compilers can be trusted, I guess.

Just out of curiosity, is the RPM intended for ADA, or C, ... or assembler?

>LIMITED SIZE ?  Well, for now, maybe, but there's no reason that
>eventually the entire 8 gigabytes of space afforded by the
>architecture cant be (at least virtually) available. Well,
>I guess now that you mention it, 8 gigabytes IS a limit. :-)
-- 
-john mashey	DISCLAIMER: <generic disclaimer, I speak for me only, etc>
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