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From: mahar@weitek.UUCP
Newsgroups: comp.arch
Subject: Re: Using a DMA chip in strange ways
Message-ID: <298@attila.weitek.UUCP>
Date: Thu, 19-Feb-87 15:43:41 EST
Article-I.D.: attila.298
Posted: Thu Feb 19 15:43:41 1987
Date-Received: Sun, 22-Feb-87 03:15:36 EST
References: <4343@columbia.UUCP>
Distribution: world
Organization: WEITEK Corp. Sunnyvale, CA
Lines: 18
Summary: use the memory management hardware to send messages

In article <4343@columbia.UUCP>, dupuy@amsterdam.columbia.edu (Alexander Dupuy) writes:
>     Since the DMA chip on your favorite disk/tape controller works by stealing
> bus cycles when the CPU is busy with other things (like arithmetic), would
> there be any advantage in having a DMA chip which would simply be used for
> memory to memory copies (from user to kernel space, or from one user space to
> another)?
> 
The memory management hardware could be used to send messages between the
OS and tasks if messages were multiples of the page size. This could reduce
message transfer time a lot.

-- 

	Mike Mahar
	UUCP: {turtlevax, cae780}!weitek!mahar

	Disclaimer: The above opinions are, in fact, not opinions.
	They are facts.