Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!tut.cis.ohio-state.edu!quanta.eng.ohio-state.edu!kcgl1.eng.ohio-state.edu!GEOMAGIC
From: GEOMAGIC@kcgl1.eng.ohio-state.edu (Daniel OConnell)
Newsgroups: comp.sys.dec
Subject: Re: DS3100 Hangs - Any Ideas Why?
Message-ID: <4279@quanta.eng.ohio-state.edu>
Date: 19 Feb 90 20:54:30 GMT
References: <8331@bunny.GTE.COM>
Sender: news@quanta.eng.ohio-state.edu
Organization: Ohio State University
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>My DECStation 3100 has the annoying habit of occasionally becoming
>thoroughly hung -- totally wedged such that the only possible recovery
>is to reboot.  I am wondering why, and I thought I might ask the net-folk
>if anyone has observed similar symptoms and has figured out what's going on.

>The problem is seemingly random, although it usually occurs when I am doing
>some heavy compiling.  The machine will be humming along, banging away at
>the disk and generally keeping itself busy, when all of a sudden it becomes
>eerily quiet.  No response to the keyboard or mouse, no disk activity, no
>response to the Ethernet -- it is as though the CPU has simply halted with
>no way to bring it back to life.

My DECStation 3100 exhibited similar behavior during a Fortran (2.0e) compile
of a 2000 line main program with level -O2 optimization. After an hour
it finally printed the message:

Out of swap space

and went into a macro funk. The 3100 has 16 Mb of memory! So I tried the
same procedure on our DECSystem 5400 which has 32 Mb of memory. The compiler
needed 16 free Mb to compile and it took 10 mins. By comparison it only
took 13 seconds to compile the same code at optimization of -O1.

Conclusion: If your running Ultrix, suspect the software first.

Ultrix sucks, but it sucks fast (but sometimes it just sucks air).

Dan O'Connell
geomagic@kcgl1.eng.ohio-state.edu
geomagic@geo1s.mps.ohio-state.edu