Path: utzoo!mnetor!uunet!husc6!mailrus!ames!pasteur!ucbvax!CITHEX.CALTECH.EDU!carl
From: carl@CITHEX.CALTECH.EDU (Carl J Lydick)
Newsgroups: comp.os.vms
Subject: RE: System memory tuning, and please help with a modem program
Message-ID: <880319025304.367@CitHex.Caltech.Edu>
Date: 19 Mar 88 11:01:19 GMT
Sender: usenet@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 44


 > What is missing in SET HOST/DTE is the capability to keep a session
 > log-file part of the time, typically for downloading: dial out via
 > modem, log into the remote machine, switch the log on, type a file out,
 > switch the log off again. Therefore, we use a program called HOST (comes
 > from Fermilab), which does that quite nicely, and is also otherwise easy
 > to use (it does all the allocate, sets the speed, and can even do
 > uploading, but we hardly ever user that).
 > 
 > Now the problem is the following: this HOST program is incredibly
 > inefficient, because it issues loads of QIO requests: for a typical
 > session at 2400 baud it is 300 buffered IOs per second (which makes
 > sense speed-wise). As far as i understand the code it actually issues
 > two QIO requests, but instead of just having an AST routine wait for a
 > completion it will keep a timer, and cancel all the outstanding requests
 > every time one request is answered or when the timer runs out ! As a
 > result the CPU becomes just incredibly inefficient: a glimpse into
 > MONITOR MODES shows 5 to 10% of the CPU time is spent in user mode, the
 > rest in kernel mode and on the interrupt stack. Net result: the VAX
 > becomes a virtual machine --- it is virtually dead (hardly surprising,
 > when running at 5% efficiency). We are trying to talk users who don't
 > need session log files into using SET/HOST/DTE instead of the HOST
 > program, but i don't know whether that is a lot more efficient. I have
 > looked into KERMIT, but the frog doesn't have switchable log files
 > either, and it is rumoured that he is very inefficient, too.
 > 
 > So the question is: Is there a good "modem"-type program out there,
 > which has switchable session log files, and does not cripple the CPU ?

How about SET HOST/DTE?  It DOES allow what you want.  However,  you  have  to
allocate  the  terminal  before  you  issue  the SET HOST/DTE command (this is
generally a good idea anyway, since otherwise, a buffer overflow kicks you out
of  SET  HOST/DTE, and if it's a BAD buffer overflow, tends to start a process
running LOGINOUT on the DTE you SET HOST/DTE to).  In general terms, a typical
session with selective logging looks like:
	$ ALLOCATE Tcnn MY_DTE		!allocate terminal line
	$ SET HOST/DTE MY_DTE		!SET HOST/DTE without logging
		Type what you want without logging; end with CONTROL-\
	$ SET HOST/DTE/LOG MY_DTE	!SET HOST/DTE with logging
		Do whatever you want logged; end with CONTROL-\
	$ SET HOST/DTE MY_DTE		!SET HOST/DTE without logging
		Do what you don't want logged (including, for example, logging
			out); end with CONTROL-\
	$ DEALLOCATE MY_DTE		!release terminal line