linux-kernel - Re: ima: use of radix tree cache indexing == massive waste of memory?

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Message-ID: <20101017021138.GG32255@dastard>
Date:	Sun, 17 Oct 2010 13:11:38 +1100
From:	Dave Chinner <david@...morbit.com>
To:	"J.H." <warthog9@...nel.org>
Cc:	"H. Peter Anvin" <hpa@...or.com>,
	Christoph Hellwig <hch@...radead.org>,
	linux-kernel@...r.kernel.org, Mimi Zohar <zohar@...ibm.com>,
	devel@...ts.fedoraprojet.org
Subject: Re: ima: use of radix tree cache indexing == massive waste of
 memory?

On Sat, Oct 16, 2010 at 05:54:11PM -0700, J.H. wrote:
> There does seem to be a boot option to disable it, but it seems to be on
> by default if it's compiled in, and it's not like it's obvious that this
> is there and chewing up resources, is there a way to find out how much
> memory this is chewing up?

$ grep iint_cache /proc/slabinfo | awk '// { print $2 * ($4 + 560) / 1048576 "MiB" }'
1164.91MiB
$

$ while [ 1 ]; do
> grep iint_cache /proc/slabinfo | awk '// { print $2 * ($4 + 560) / 1048576 "MiB" }'
> sleep 5
> done
955.706MiB
937.438MiB
928.851MiB
920.912MiB
919.067MiB
919.086MiB
919.111MiB
.....

This is only with about 1.2M inodes cached - yesterday I saw the
inode cache grow to 3.5M inodes during an rsync run....

Also, it's doing a good job of fragmenting the radix tree node cache
- it's currently at 50% population - 3.8M entries, 1.9M in use. i.e.
wasting another ~1GB of RAM itself right now....

Cheers,

Dave.
-- 
Dave Chinner
david@...morbit.com
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