slow throughput

[Robert J. Granvin]

Well, I've been trying to avoid posting, mostly because I haven't been
paying attention to the newsgroup for a while and have no idea if this
or similar has been hashed out before.  That, and getting through to
Microport technical support is an adventure in patience.

Anyways, we're running Microport 2.4 on an Everex 1800 '286 with 1.5MB
RAM, HoneyDanBer UUCP and various miscellaneous stuff.

This box is connected via serial connection to an NCR Tower 650 (yes,
correctly).  The line is just a plain old ordinary direct link running
at 9600 baud.

The problem is throughput.  The logs and uucp traffic summaries show
that transmission runs at an average of 105 CPS.  Pretty lousy for a
9600 baud line.  While running a connection in debug mode, the data
packets are bursted out and really do transmit at 9600 baud.  However,
every 5 to 20 packets (always variable), the transmission halts, an
alarm is generated, another pause and then another burst of packets
goes through.  The delays are much longer than the packet bursts,
which is causing the low throughput totals.

Microport made one suggestion: lower the baud rate and the throughput
should go up.  They assumed that the data is being received too fast
and the machine needs some packet rebroadcasts, killing throughput.  I
certainly didn't believe this since standard PC equipment is more than
happy to handle 19.2K transmission effortlessly, and the Tower
certainly doesn't care.  Also, it doesn't matter which end is sending
a file.  Either direction, and no matter who originates the
connection, the throughput always stays around 105 CPS.

Anyways, just in case, it was tried.  Any speed above 300 baud shows a
throughput of about 105 CPS.  No difference.

So, after all of that, any suggestions?  Being familiar with lots of
different machines, but least so of a Microport based PC, I'm looking
for hints.  Does anyone else run a serial port to another unix machine
at 9600?  If so, how did you configure it?  gettydefs, inittab, etc.
It's possible I've got something configured incorrectly, but
everything I've set up on the Microport box is the same as has been
done successfully on many other machines.

Please email any hints, suggestions, comments or configuration
examples.  I, my boss and everyone else peeking over my shoulder would
be rather pleased.  I'll summarize if there's enough interest in the
results.

Thanks in advance...

-- 
       Robert J. Granvin            "A cowboy should know his horse, but it
 National Information Services       seemed to the podners at the Triple Q
       rjg at sialis.mn.org             Ranch that Vernon McChew had gotten TOO
{amdahl,hpda}!bungia!sialis!rjg      close."