From: Andrew Morton <akpm@linux-foundation.org>
To: Dave Chinner <david@fromorbit.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>,
Ext4 Developers List <linux-ext4@vger.kernel.org>,
gnehzuil.liu@gmail.com, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH] fs: allow for fs-specific objects to be pruned as part of pruning inodes
Date: Thu, 24 Jan 2013 00:58:16 -0800 [thread overview]
Message-ID: <20130124005816.bce599de.akpm@linux-foundation.org> (raw)
In-Reply-To: <20130123133231.GS2498@dastard>
On Thu, 24 Jan 2013 00:32:31 +1100 Dave Chinner <david@fromorbit.com> wrote:
> Also, the superblock shrinker is designed around a direct 1:1:1
> dependency relationship between the superblock dentry, inode and "fs
> cache" objects. i.e. dentry pins inode pins fs cache object. It is
> designed to keep a direct balance of the three caches by ensuring
> they get scanned in amounts directly proportional to the relative
> differences in their object counts. That can't be done with
> separate shrinkers, hence the use of the superblock shrinker to
> define the dependent relationship between the caches.
I was staring at the code and at the 0e1fdafd9 changelog trying to work
out why prune_super() does its weird shrinker-in-a-shrinker thing. And
failing.
IOW it needs a code comment, please. Ideally one which explains *why*
"It is designed to keep a direct balance of the three caches...". What
would go wrong if the fs were to just register its own shrinker in the
expected manner?
next prev parent reply other threads:[~2013-01-24 8:58 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20130121170937.GB15473@gmail.com>
2013-01-23 6:06 ` [PATCH] fs: allow for fs-specific objects to be pruned as part of pruning inodes Theodore Ts'o
2013-01-23 10:52 ` Jan Kara
2013-01-23 13:06 ` Carlos Maiolino
2013-01-23 13:32 ` Dave Chinner
2013-01-23 16:34 ` Theodore Ts'o
2013-01-23 23:35 ` Dave Chinner
2013-01-24 8:58 ` Andrew Morton [this message]
2013-01-24 20:03 ` Dave Chinner
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