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Date: Tue, 13 Apr 2010 15:31:54 +0200
From: Andrea Arcangeli <aarcange@redhat.com>
Subject: Re: [PATCH 00 of 41] Transparent Hugepage Support #17
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To: Neil Brown <neilb@suse.de>
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Hi Neil!

On Tue, Apr 13, 2010 at 04:18:02PM +1000, Neil Brown wrote:
> Actually I don't think that would be hard at all.
> ->lookup can return a different dentry than the one passed in, usually using
> d_splice_alias to find it.
> So when you create an inode for a directory, create an anonymous dentry,
> attach it via i_dentry, and it should "just work".
> That is assuming this is still a "problem" that needs to be "fixed".

I'm not sure if changing the slab object will make a whole lot of
difference, because antifrag will threat all unmovable stuff the
same. To make a difference directories should go in a different 2M
page of the inodes, and that would require changes to the slab code to
achieve I guess.

However while I doubt it helps with hugepage fragmentation because of
the above, it still sounds a good idea to provide more "free memory"
to the system with less effort and while preserving more cache.

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