*BSD News Article 25561


Return to BSD News archive

Path: sserve!newshost.anu.edu.au!munnari.oz.au!constellation!osuunx.ucc.okstate.edu!moe.ksu.ksu.edu!vixen.cso.uiuc.edu!sdd.hp.com!caen!hellgate.utah.edu!fcom.cc.utah.edu!u.cc.utah.edu!cs.weber.edu!terry
From: terry@cs.weber.edu (A Wizard of Earth C)
Newsgroups: comp.os.386bsd.questions
Subject: Re: CDROM support
Date: 4 Jan 1994 18:44:45 GMT
Organization: Weber State University, Ogden, UT
Lines: 17
Message-ID: <2gcdet$bkk@u.cc.utah.edu>
References: <2g5qaq$ng0@u.cc.utah.edu> <DykkFc3w165w@oasys.pc.my>
NNTP-Posting-Host: cs.weber.edu

In article <DykkFc3w165w@oasys.pc.my> othman@oasys.pc.my (Othman Ahmad) writes:
[ ... ]
>Beware though that direct memory read can be faster than any DMA given the
>right processor.

Only true if you bought the wrong bus or the wrong board.  The primary
utility of bus-mastering DMA is that the main processer can keep doing
whatever it needs to do as long as it does it in cache -- a minor case
of parallel processing.  A machine that can do two things at once is
generally faster than a machine that can only do one thing at a time.


					Terry Lambert
					terry@cs.weber.edu
---
Any opinions in this posting are my own and not those of my present
or previous employers.