Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!iuvax!purdue!decwrl!sgi!dunlap@bigboote.csd.sgi.com
From: dunlap@bigboote.csd.sgi.com (D. Christopher Dunlap)
Newsgroups: comp.sys.sgi
Subject: Re: /debug size
Summary: I guess my earlier posting didn't get out...
Message-ID: <38126@sgi.SGI.COM>
Date: 17 Jul 89 14:47:43 GMT
References: <1008@amethyst.math.arizona.edu>
Sender: daemon@sgi.SGI.COM
Organization: Silicon Graphics, Inc., Mountain View, CA
Lines: 74

In article <1008@amethyst.math.arizona.edu>, chris@spock.ame.arizona.edu (Chris Ott) writes:
> 
> lewis@castor.wustl.edu (Lewis Yuchan Geer) writes:
> > Is there any way to reduce the size of /debug, as it acts like it takes
> > up 50Mb on our system?  Is this a wise thing to do?  Thanks.
> 
>      No, it's not a wise thing to do. The /debug partition is actually
> the swap partition for the IRIX system. Reducing its size will reduce
> the amount of virtual memory available to all of the processes on the
> system.
> 

Almost right. It's actually ALL the virtual space. Real memory AND
swapspace.

>      Do an "ls" on /debug. Notice that all of the files' names are
> numbers, rather than words. Now do a "ps". Notice that most of the PIDs
> listed by "ps" match the file names in the /debug partition. Reading and
> writing these files is the same as reading and writing the memory space of
> the corresponding process. It is used mostly by the debugger for reading
> and writing variables, hence the name /debug. Quite an ingenious idea on
> Silicon Graphics' part, in my opinion (if it was they who invented it).
> 

Yep. That's how it works. I'm not sure of the origin of the idea. 

> > So why even show it in the "df" display?
> 
>      Probably because it's a file system, just like / and /usr. The
> amount of memory available (displayed by "df") represents the amount of
> virtual memory left on your system. Personally, I like it.
> 

I think it's mostly to make work for the Hotline. ;-}


> >                                 since no one from SGI offered any advice, I
> > thought I'd try to help.
> 
>      Yeah, I'm surprised at this. They're usually pretty helpful. Maybe
> it's because it's the weekend...
> 
> Chris

Hmmmm. I posted an article some time ago. (When I first saw the
original) Maybe it didn't get out? Or maybe my .signature isn't 
getting stuck on my postings all of a sudden? So I'll put one on 
manually just to be sure...

See ya,


chris


------

D. Christopher Dunlap

Support Team Manager
Hardware Product Support		(aka "The Geometry Hotline")
Customer Support Division
Silicon Graphics Computer Systems




--

D. Christopher Dunlap		email: dunlap@sgi.sgi.com

Hardware Product Support 
Customer Support Division
Silicon Graphics Computer Systems