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Date: Wed, 22 Mar 1995 20:19:58 +1000
From: Bruce Evans <bde@zeta.org.au>
Message-Id: <199503221019.UAA09977@godzilla.zeta.org.au>
To: hasty@star-gate.com, phk@ref.tfs.com
Subject: Re: Why IDE is bad
Cc: faq@FreeBSD.org, hackers@FreeBSD.org
Sender: hackers-owner@FreeBSD.org
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>I don't think you will find many ide's faster than the WDC, I know
>it can run faster on a better IDE-controller, but this is a fairly
>standard IDE controller so it's a good indication.
>And yes, but FreeBSD doesn't support DMA in IDE (yet ?)...

The WDC specs that I've seen show DMA speeds slightly slower than
IDE speeds so DMA may not be worth using.

I forgot to think about the possibility of overlapping DMA cycles
with cpu cycles in my previous mail about this.  I reported a 28%
slowdown for counting to 100000000.  The cpu mostly executes 2
instructions in a loop.  There should be few bus accesses to slow
the cpu down.  Maybe busmastering is broken.

Bruce