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    SubjectRe: wierd behaviour...
    On Wed, 26 Feb 1997, Marc Lehmann wrote:

    > Date: Wed, 26 Feb 1997 20:57:46 +0100 (MET)
    > From: Marc Lehmann <mlehmann@hildesheim.sgh-net.de>
    > To: koenig@tat.physik.uni-tuebingen.de
    > Cc: linux-kernel@vger.rutgers.edu
    > Subject: Re: wierd behaviour...
    >
    >
    > >too complicated tests give wierd results and wrong conclutions... try
    >
    > You should have tried it..
    >
    > >and you'll realize that these writes are ~5-10 secs after you start the image.
    >
    > You SHOULD have tried it.. the writes are instant. run it in a shell-loop,
    > and your drive light keeps going all the time!
    >
    > I didn't believe it at first, but:
    >
    > main(){ pause(); }

    I think, to identify it actually as a fork related problem, you can try this
    code (I'm sure you won't get disk light flashin in this case):

    main () {
    while ()
    if (!fork ())
    exit (0);
    else sleep (1);
    }

    If you don't get hd lights flashing in this case, you are identifying
    incorrectly the problem.

    >
    > compiled, started, and interrupted does nothing (well, after
    > some time, the atime is updated).. as one would expect.
    >
    > main(){ fork(); }
    >
    > on the other hand DOES write to my harddisk, quite loudly, BTW..
    > this has NOTHING to do with the atime update.
    >
    > after killing syslogd (maybe some log-file gets written), I still
    > get the disk-activity...
    >
    > checked under 2.1.14 (the last one that did compile so far :-)
    >
    > btw:
    > void main(void) { if(fork()) sleep(2); else sleep(1);}
    >
    > shows this behavious, while
    >
    > void main(void) { if(fork()) sleep(1); else sleep(2);}
    >
    > does not... (except for the atime update, which is much later..)
    > i.e. if the child dies BEFORE the parent we get the behaviour,
    > not otherwise round.. (hmm.. I thought it would be
    > an interatcion with init or the shell, but...)
    >
    > ---------------------------------------------------------------------
    >
    > for a pentium-optimizing gcc, look at http://www.goof.com/pcg
    >
    > -----==-
    > ----==-- _
    > ---==---(_)__ __ ____ __ Marc Lehmann
    > --==---/ / _ \/ // /\ \/ / mlehmann@hildesheim.sgh-net.de
    > -=====/_/_//_/\_,_/ /_/\_\ pcg@goof.com
    > The choice of a GNU generation
    >

    Luis Colorado <luis.colorado@ts.es>
    Telefonica Sistemas, S.A.
    C/Ramirez de Arellano 19 / 28043 MADRID (SPAIN)
    Tel: 34.1.337.5830 / Fax: 34.1.337.5709


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