Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ncar!husc6!mit-eddie!apollo!bither
From: bither@apollo.HP.COM (David Bither)
Newsgroups: comp.dcom.lans
Subject: Re: Smart vs. Dumb Ethernet Cards
Keywords: Does smart on fast => slow?
Message-ID: <453e51b1.11a92@apollo.HP.COM>
Date: 25 Aug 89 17:18:00 GMT
References: <8960@pyr.gatech.EDU>
Distribution: usa
Organization: Apollo Computer, Chelmsford, Mass.
Lines: 20

>I have heard that "smart" Ethernet cards actually reduce throughput
>on fast PCs.  This seems to be because the 80188 on the card working
>full time is slower than a 80386/20 or 25 working part time.  Is this
>true?   If so, at what processor speed does this make a difference?

Like all religious questions, it's a complex issue with no simple answers.
IF the smart card processor is significantly slower than the CPU, and
IF the task is single-threaded (i.e. the CPU has nothing better to do
than wait for the transaction to complete) THEN a dumb card can provide
better performance.  In general, smart cards have a higher throughput
that is only realizable in parallel or pipelined environments where
some concurrency is advantageous.  In general, dumb cards have a lower
latency which will translate into better performance in a single-threaded
environment.

My experience with 3Com's Etherlink Plus card has taught me that unless
you can use the intelligence to do some useful protocol processing, the
board will be slower than a dumb board.

Dave Bither