Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ames!lll-lcc!pyramid!romain
From: romain@pyramid.pyramid.com (Romain Kang)
Newsgroups: comp.dcom.modems
Subject: Re: Telebit transfer rate problem
Message-ID: <64160@pyramid.pyramid.com>
Date: 27 Mar 89 05:57:21 GMT
References: <640@island.uu.net>
Reply-To: romain@pyramid.pyramid.com (Romain Kang)
Organization: Pyramid Technology Corp., Mountain View, CA
Lines: 38

In article <640@island.uu.net> brad@island.uu.net (Bradley Mabe) writes:
| When connecting to another site via uucp in pep mode we get an average 
| send rate of around 1200 bytes per second, but and average receive rate 
| of only 500 bytes per second. The modems are connected to a sun 2/170 via 
| a 16 channel systec multiplexer and we are running sunOS 3.2.

Since no one else has responded, I guess I'll stick my neck out:  Maybe
a 2/170+Systech doesn't have the horsepower to receive any faster.
Remember, one reason 't' protocol was invented was that VAX 11/780's
running 'g' peaked out at about 900 bytes/sec over TCP/IP sockets, with
the data DMA'd in, avoiding the tty overhead.  Here you have a CPU
that's probably slower; each character received means a CPU interrupt
and a couple of context switches, and has to filter through the raw tty
interface.  Sending may be that much more CPU-efficient.

I see several possible solutions:
	1. Get a faster processor (perhaps not easy for you).
	2. Get a modernized UUCP.  A SysV termio interface with VMIN
	   and VTIME set to reasonable values, or a high resolution
	   sleep (like select()) might be used to avoid unnecessarily
	   scheduling uucico.
	3. Get a smart terminal server to handle the TrailBlazer.  Some
	   time back, Rutgers hacked their Cisco servers to allow UUCP
	   logins to use port 540, thus avoiding the tty overhead.  I
	   think I was able to get 1350-1400 cps before this feature
	   disappeared.
	4. Put 'g' protocol in the kernel, where God meant it to be.
	   I think Peter Honeyman once said you couldn't be considered
	   serious about UUCP if you hadn't hacked your kernel for it
	   somehow.

Two years ago, I cited the VAX statistics and claimed the UUCP spoof
was no substitute for intelligent front-end hardware and more efficient
protocols.  Oops.  Today, someone with a 80386 box and a decent serial
card can do 'g' protocol faster than a '780.  Time to find a predictable
occupation, like migrant farm worker...
--
"Eggheads unite! You have nothing to lose but your yolks!"  -Adlai Stevenson