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From: benseb@grumpy.sdsc.edu (Booker Bense)
Newsgroups: comp.sys.next,comp.dcom.modems
Subject: Tuning slip on a T2500/NextStation
Message-ID: <456@nic.cerf.net>
Date: 16 Jun 91 17:49:27 GMT
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Followup-To: comp.sys.next
Organization: San Diego Supercomputer Center @ UCSD
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Originator: benseb@grumpy.sdsc.edu

- Well, I've been banging on a version of slip for the NeXT for about
a month. The connection is t2500 to t2500 and I generally run it in 
pep mode. 

- A back of the envelope calculation reveals:

 (19200 / 8 ) = 2400 bytes/sec * (2/3 data/tcp packet length ) = 1.6
Kbytes /sec ftp transfer rate.

Or in other words , I shoud expect an optimal ftp rate of about 1.5
Kb/sec.

- When I first started I was seeing about a 0.4 kb/sec coming in and
0.6 going out. Since I am on a 8mb next I played around with renicing 
the diald deamon and have acheived rates of 

0.6-0.7 coming in 

0.9-1.5 going out

- I have seen some short outgoing transfers achieve the 1.6 kb/sec rate, so
I know it's possible, at least for a short while. This is running
regular slip ( I know I shoud be using cslip or PPP but it's not an
option at this point. ) 

- The line is not the greatest , the pep connection has to retrain
about every hour or so. Varying the modem settings does not seem to
have much effect. I'm not really concerned with interactivity, fast
ftp is much more important!! (I use ange-ftp with emacs to do remote
editing on my local machine and reccomend it highly!! (available from
tut.cis.ohio-state.edu )).

- The only thing so far that I have found that really effects speed is
niceing the diald deamon. In my rc.slip I have 
( Note: this is the sh nice , not the csh one !!!)
nice --10 /usr/dialupip/diald -d 4

- I don't think you want to set the priority any higher than this, the
swapper runs at -12 (16) . I don't think it would be a good idea to run
anything at a higher priority than this. Note:( ps -agl returns a
proirity that is based on the scale (0-19) (0 least cpu 19 most cpu ) ,
nice works on a scale of ( -20 20) ( -20 most cpu 20 least cpu).

-So , what kind of ftp speeds have you got and on what kind of setup?
Would getting more memory help the suitation? ( I'm probably going to
do this anyway, getting a definitive yes answer would merely speed up
the process. ) It's probably a swapping problem as there are
definitely times during a long transfer when neither the read or send
lites are blinking.

- Booker C. Bense                    
prefered: benseb@grumpy.sdsc.edu	"I think it's GOOD that everyone 
NeXT Mail: benseb@next.sdsc.edu 	   becomes food " - Hobbes