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Date:      Fri, 1 Sep 1995 17:01:07 +1000
From:      Bruce Evans <bde@zeta.org.au>
To:        davidg@Root.COM, pst@shockwave.com
Cc:        hackers@freebsd.org
Subject:   Re: novell ne2000 cards with FreeBSD...opinions?
Message-ID:  <199509010701.RAA31341@godzilla.zeta.org.au>

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>>What kind of performance can I expect to see on a NE2000 vs a 16 bit SMC card
>>when running FreeBSD?
>>
>>e.g. would you dare build a diskless NFS client with a NE2000 clone?

>   It will require twice the CPU, and in some extreme cases, this might be
>enough to cause it to drop a packet. ...but normally it will work fine.

I.e., it would require about 100% of the cpu instead of only about 50%.
This is very dependent on the number of wait states for the ISA bus.

I use NE2000/WD8013EBT clones in WD mode and see the following overheads:

486DX2/66 ttcp -t:	21% Sys   51% Intr
486DX /33 ttcp -t:	29% Sys   51% Intr
486DX2/66 ttcp -r:	17% Sys   52% Intr   1094.78 KB/sec
486DX /33 ttcp -r:	22% Sys   58% Intr   1098.10 KB/sec

In NE2000 mode the interrupt overhead goes up enough for at least the
DX/33 to run out of cycles - 100% of the cpu is used and the speed drops
to about 1000 KB/sec.

Bruce



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