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Date: Sun, 3 Sep 1995 07:36:08 +1000
From: Bruce Evans <bde@zeta.org.au>
Message-Id: <199509022136.HAA13401@godzilla.zeta.org.au>
To: bde@zeta.org.au, davidg@Root.COM
Subject: Re: novell ne2000 cards with FreeBSD...opinions?
Cc: hackers@freebsd.org
Sender: hackers-owner@freebsd.org
Precedence: bulk

>>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
>>memory instead of more that half its time doing explicit i/o instructions.
>>The speeds are something like:
>>
>>	i/o instructions:	2MB/sec
>>	bcopy:			3MB/sec
>>	IDE disk controllers:	3.3MB/sec	PIO mode 0 (or 1?) spec
>>	8MHz ISA bus max:	4MB/sec

>   Your bus is slow. The 8013 usually has memory speeds of 4MB/sec.

Isn't a slow bus the usual case?  On one of my systems, the (AMI) BIOS
has options for 1-5 bus wait states but not 0.  I use 1.  There are
options to use a faster bus speed but I don't use them.  On another of
my systems, the (AMI) BIOS doesn't have any bus options.  It apparently
defaults to 2 bus wait states.

I timed the speeds more carefully using microtime() before and after each
relevant bcopy and insw/outsw:

				System 1 (486DX/33,1ws)	System 2 (486DX2/66)
NE2000 16 bit i/o instructions	2.0byte/us		test not done
WD8013EBT shared memory		3.5byte/us		3.0 byte/us
IDE 16 bit i/o instructions	3.0byte/us 		test not done

Bruce