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From: davidsen@steinmetz.steinmetz.UUCP (William E. Davidsen Jr)
Newsgroups: comp.unix.xenix
Subject: Re: Adding ports to SCO XENIX system
Message-ID: <7702@steinmetz.steinmetz.UUCP>
Date: Mon, 26-Oct-87 16:35:16 EST
Article-I.D.: steinmet.7702
Posted: Mon Oct 26 16:35:16 1987
Date-Received: Wed, 28-Oct-87 05:44:44 EST
References: <94@sda.atexrd.UUCP> <787@ssc.UUCP> <7433@dartvax.UUCP> <608@omen.UUCP>
Reply-To: davidsen@crdos1.UUCP (bill davidsen)
Organization: General Electric CRD, Schenectady, NY
Lines: 31
Keywords: ports SCO XENIX

In article <608@omen.UUCP> caf@omen.UUCP (Chuck Forsberg WA7KGX) writes:
|In article <7433@dartvax.UUCP> cmi@dartvax.UUCP (Theo Pozzy/R. Green) writes:
|:We've pounded on it by using our software, MLINK, to do 9600 baud
|:file transfers with one port looped back into another, with two
|:loops running at once!
|
|A loopback test such as this is not necessarily a good prediction of real
|world performance because the loopback configuration tends to regulate
|the flow of data.  The result is an implicit, unexpected flow control.

This is true. However, when running the loopback test, if the actual
throughput is about right for a 9600 baud connection the system will
handle one line at 9600, and unless the port controller buffers output
but not input (I guess you could do it that way), it will handle two.

A reasonable estimation of throughput is the time the ports with a null
modem and connect out on one and login on the other. You can then 'cat'
a file and time it by hand. I like to use a file which takes at least 30
sec to transfer at the maximum line rate.

I ususally test the throughput with both kermit and zmodem file
transfers. Kermit will usually get about 45-55% of max, zmodem about
90-93%. Look for a large number of retries, particularly on kermit.

Running a loopback test without timing is not usually meaningful except
to test the ability of the system to transfer *something* without
aborting with a system fault such as "double panic."
-- 
	bill davidsen		(wedu@ge-crd.arpa)
  {uunet | philabs | seismo}!steinmetz!crdos1!davidsen
"Stupidity, like virtue, is its own reward" -me