Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!dali.cs.montana.edu!uakari.primate.wisc.edu!zaphod.mps.ohio-state.edu!pacific.mps.ohio-state.edu!linac!highspl!fithp!mhw
From: mhw@fithp (Marc Weinstein)
Newsgroups: comp.sys.3b1
Subject: Re: more on the HFC saga
Message-ID: <1991May25.062939.22352@fithp>
Date: 25 May 91 06:29:39 GMT
References: <1991May23.133742.560@ceilidh.beartrack.com>
Organization: Weinstein Consulting
Lines: 29

From article <1991May23.133742.560@ceilidh.beartrack.com>, by dnichols@ceilidh.beartrack.com (DoN Nichols):
> In article <1991May22.042143.13250@fithp> mhw@fithp (Marc Weinstein) writes:
>>From article <103431@becker.UUCP>, by bdb@becker.UUCP (Bruce D. Becker):
> 
>>> 	Doing compression in the
>>> 	modem seems wasteful of resources due
>>> 	to the fact that uncompressed data gets
>>> 	pumped thru the serial interface with
>>> 	an interrupt service routine invocation
>>> 	for each character!
>>
>>Hmmm - don't understand the logic here.  If I want to send a file to
>>someone, and I know my modem will compress the file anyway, then I don't
>>have to bother with compressing the file before the fact.  Less wory,
>>less bother.
> 
> 	If you pre-compress the file, that's fewer characters through your
> serial interface, and therefore fewer interrupts.  And, since the
> transmission speed between modems is fixed (after compression), the fewer 
> interrupts per unit time (on the average).  It's the high rate of interrupts
> that really brings the system to its knees.

True enough.  In this context, I agree.  I just don't see this as an
argument for turning off compression in the modem by default.

-- 
Marc Weinstein
{simon,royko,tellab5}!linac!fithp!mhw		Elmhurst, IL
-or- {internet host}!linac.fnal.gov!fithp!mhw