From owner-freebsd-hackers  Sat Sep  2 18:06:45 1995
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Date: Sat, 2 Sep 1995 21:07:34 -0400
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To: hackers@freebsd.org
From: dennis@et.htp.com (dennis)
Subject: Re: novell ne2000 cards with FreeBSD...opinions?
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>>>Shared memory on my NE2000/WD8013EBT card is 50% faster, but that isn't
>>>saying much.  The driver spends half its time bcopying to the shared
>>>...
>>The bus transfer itself is a pretty small piece of the latency puzzle. But
>>with a PIO card you have setup operations for every transfer...whereas with
>>shared memory you can access individual bytes and the buffer without setup
>>latency.
>
>The `ed' driver does bulk copies in both cases.  Random access would
>only be significantly faster if some of the data is never looked at and
>none of the data is looked at twice.
>

Except when you're reading the header. It changes the way that you implement
the logic.

db