Subject: Re: i386 1.4Q hangs nonrandomly?
To: Matthew Orgass <>
From: Simon Burge <>
List: current-users
Date: 01/28/2000 13:59:23
Matthew Orgass wrote:

>   Hmm, heavy memory load... sounds familiar:  I've noticed that running
> "grep foo /dev/zero &; grep foo /dev/zero &;"  will lock up my system
> within a minute 100% of the time when X is running.
> ...
> It looks like it gets stuck in a
> loop and spends most or all of its time in uvmpd_scan.  I just sent in a
> pr (kern/9308).  Sounds like this might possibly be what is happening to
> you.

Initially I'd guess it was a different problem.  Note that grep(1)
will allocate memory for the contents of a file until it hits a \n,
and obviously this doesn't occur for /dev/zero.  With two greps on
/dev/zero, you'll very quickly get two processes trying to allocate
a large amount of memory (128MB each on my -current i386).  How much
RAM and swap does your box have?

The maintainer of GNU grep says that you should have enough virtual
memory to allocate the longest line possible, and doesn't want to
change that behaviour...