From owner-freebsd-bugs  Sat Sep 22 14:10: 4 2001
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Date: Sat, 22 Sep 2001 13:50:45 -0700
From: David Greenman <dg@root.com>
To: Mike Barcroft <mike@FreeBSD.org>
Cc: freebsd-bugs@FreeBSD.org
Subject: Re: kern/19479: processes stuck in 'ffsvgt' and 'FFS no' states
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>      FFS node204489102245K 102245K102400K   663650    0     0  512
> <deadlock here!>
> 
> 102245K seems like an awful lot of memory for FFS nodes?
> what would cause this?   does anyone else see very large FFS node
...
> clearly we are reaching the malloc limit for "FFS node" and hanging.

   Yes, and it is easy to reproduce. Just read/write a lot of files (a few
hundred thousand) on a machine with a lot of memory (1GB or more). The
problem is caused by FreeBSD's overly agressive desire to keep vnodes (and
their attached FS nodes) around in order to be able to cache the associated
file data. I haven't looked at the problem in great detail (I would have a
fix for this if I had), but basically there needs to be a cap on how many
vnodes are allowed to stick around after all the references have been dropped
and vnodes with no cached pages should be freed immediately. There used to
be such a cap, but someone removed it a long time ago.

-DG

David Greenman
Co-founder, The FreeBSD Project - http://www.freebsd.org
President, TeraSolutions, Inc. - http://www.terasolutions.com
Pave the road of life with opportunities.

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