Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!ncar!asuvax!mcdphx!udc!dfields
From: dfields@urbana.mcd.mot.com (David Fields)
Newsgroups: comp.arch
Subject: Re: SRAM vs. DRAM, 33MHz 386 UNIX-PC
Message-ID: <1063@urbana.mcd.mot.com>
Date: 14 Sep 89 14:39:24 GMT
References: <27133@proton.mips.COM> <7857@cbmvax.UUCP>
Reply-To: dfields@urbana.mcd.mot.com (David Fields)
Organization: Motorola Microcomputer Division, Urbana IL
Lines: 20

In article <7857@cbmvax.UUCP> daveh@cbmvax.UUCP (Dave Haynie) writes:
>in article <27133@proton.mips.COM>, wilkes@mips.COM (John Wilkes) says:
>> 
>> In article <7851@cbmvax.UUCP> daveh@cbmvax.UUCP (Dave Haynie) writes:

Context:
	[A discussion about flushing Unix(TM) flushing caches between
		every context switch with virtual caches and whether
		it physical caches could retain usefull data after
		a context switch.				MDF]

>You are guaranteed under today's UNIX
>at least that two tasks won't be sharing any memory.  So whatever's cached up

That's not quite correct.  Both 4.3BSD and SysV have shared text,
copy-on-write data and several implementations of BSD have SysV shared
memory grafted onto them.  I'm not sure how much of this stuff remains
in cache on real systems, but ...
-- 
Dave Fields // Motorola MCD //  uunet!uiucdcs!mcdurb!dfields