From: Steven Whitehouse <swhiteho@redhat.com>
Date: Thu, 10 Jan 2008 15:18:55 +0000 (+0000)
Subject: [GFS2] Reduce inode size by moving i_alloc out of line
X-Git-Tag: v2.6.25-rc1~1241^2~7
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=6dbd822487d0a9f14432cb4680415b80656b63a2;p=pandora-kernel.git

[GFS2] Reduce inode size by moving i_alloc out of line

It is possible to reduce the size of GFS2 inodes by taking the i_alloc
structure out of the gfs2_inode. This patch allocates the i_alloc
structure whenever its needed, and frees it afterward. This decreases
the amount of low memory we use at the expense of requiring a memory
allocation for each page or partial page that we write. A quick test
with postmark shows that the overhead is not measurable and I also note
that OCFS2 use the same approach.

In the future I'd like to solve the problem by shrinking down the size
of the members of the i_alloc structure, but for now, this reduces the
immediate problem of using too much low-memory on x86 and doesn't add
too much overhead.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
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