Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!ukma!husc6!bu-cs!bzs
From: bzs@bu-cs.BU.EDU (Barry Shein)
Newsgroups: comp.unix.questions
Subject: Re: A vigorous getty
Message-ID: <35494@bu-cs.BU.EDU>
Date: 29 Jul 89 18:06:12 GMT
References: <1923@leah.Albany.Edu>
Organization: Boston U. Comp. Sci.
Lines: 37
In-reply-to: rds95@leah.Albany.Edu's message of 27 Jul 89 19:56:30 GMT


>Every once in a while, my system does this strange thing where
>getty starts taking mucho cpu cycles. For example, right now there
>are 2 gettys taking up 90% of the machine cycles. All the other gettys
>look normal, i.e., they're just sitting asleep. Killing the offenders
>just spawns a couple new ones, of course; if I turn the offending 
>lines off in /etc/ttys and then kill the processes, they still come back.

Almost certainly a hardware setup problem, getty thinks someone is
coming in on the line and then changing its mind (or thereabouts.) One
strong possibility is a very noisy terminal line or a grounding
problem somewhere so garbage keeps coming in.

It's possible you have modem control enabled on the lines in question
but don't have the modem lines wired properly, either shut off modem
control or re-wire the lines, particularly dtr, cd and rts/cts, these
might be going up and down randomly (you don't say what kind of board
this is.)

If none of this helps or makes sense in your situation I'd diag the
hardware itself, it could be a bad board tho that's less likely than
the type of thing I mentioned above.

Even if it worked yesterday a line could develop noisiness or
grounding problems if it was marginal to begin with (did someone just
install a large freezer unit near one of your terminal line runs?
etc.)

This sort of problem is often the wages of past (rs232) sins, and
usually easy to fix once you get a handle on it.
-- 
	-Barry Shein

Software Tool & Die, Purveyors to the Trade
1330 Beacon Street, Brookline, MA 02146, (617) 739-0202
Internet: bzs@skuld.std.com
UUCP:     encore!xylogics!skuld!bzs or uunet!skuld!bzs