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From: bazyar@ernie (Jawaid Bazyar)
Subject: Re: DMA?
Message-ID: <1991Apr17.143801.22825@m.cs.uiuc.edu>
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Reply-To: bazyar@cs.uiuc.edu (Jawaid Bazyar)
Organization: Mutation Testing Facility, University of Illinois
References: <613@generic.UUCP>
Date: Wed, 17 Apr 91 14:38:01 GMT
Lines: 22

In article <613@generic.UUCP> taob@pnet91.cts.com (Brian Tao) writes:
>    Since we are back on the topic of DMA devices for the time being, I have a
>question concerning the RAMFast DMA SCSI card.  I've got it hooked up to a
>Quantum 100-meg HD.  Using Prosel-16, I can get close to 600K/second on block
>reads, but some reason, block WRITES max out at barely 150K/second.  I realize
>that writing takes longer than reading, but 4 times longer?!?!  DMA is turned
>on, I have a fully-populated Chinook RAM4000 card, no RAM disk, and I'm using
>the GS/OS RAMFast driver.  Any suggestions?

   The RAMfast cache is what is termed as "write-through", i.e. any data
written to the card is immediately written through to the disk.  This is
for consistency (note that Unix machines don't operate this way- you can't
just unplug a Unix box without losing filesystem data).
   What are you using to test your speeds in K/second?
   Someone needs to write a sort of "Nortonish" utility for the ][ series.
That way we can compare ourselves at least to each other.

--
Jawaid Bazyar               |  "Twenty seven faces- with their eyes turned to
Senior/Computer Engineering |    the sky. I have got a camera, and an airtight
bazyar@cs.uiuc.edu          |     alibi.."
   Apple II Forever!        |  I need a job... Be priviliged to pay me! :-)