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Date: Thu, 12 Apr 2001 01:45:08 -0400 (EDT)
From: Alexander Viro <viro@math.psu.edu>
To: Andreas Dilger <adilger@turbolinux.com>
cc: kowalski@datrix.co.za, linux-kernel@vger.kernel.org
Subject: Re: Fwd: Re: memory usage - dentry_cacheg
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On Wed, 11 Apr 2001, Andreas Dilger wrote:

> I just discovered a similar problem when testing Daniel Philip's new ext2
> directory indexing code with bonnie++.  I was running bonnie under single
> user mode (basically nothing else running) to create 100k files with 1 data
> block each (in a single directory).  This would create a directory about
> 8MB in size, 32MB of dirty inode tables, and about 400M of dirty buffers.
> I have 128MB RAM, no swap for the testing.
> 
> In short order, my single user shell was OOM killed, and in another test
> bonnie was OOM-killed (even though the process itself is only 8MB in size).
> There were 80k entries each of icache and dcache (38MB and 10MB respectively)
> and only dirty buffers otherwise.  Clearly we need some VM pressure on the
> icache and dcache in this case.  Probably also need more agressive flushing
> of dirty buffers before invoking OOM.

We _have_ VM pressure there. However, such loads had never been used, so
there's no wonder that system gets unbalanced under them.

I suspect that simple replacement of goto next; with continue; in the
fs/dcache.c::prune_dcache() may make situation seriously better.

								Al

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