linux-ext4 - Re: [RFC v2 02/10] vfs: add support for updating access frequency

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Message-ID: <CAEH94LhvN4YFE-=j+5JD9JRdEmsbQ3OOx86WTkWT_4Eyf29u4w@mail.gmail.com>
Date:	Thu, 27 Sep 2012 10:30:05 +0800
From:	Zhi Yong Wu <zwu.kernel@...il.com>
To:	Dave Chinner <david@...morbit.com>
Cc:	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-btrfs@...r.kernel.org, linux-ext4@...r.kernel.org,
	linuxram@...ux.vnet.ibm.com, viro@...iv.linux.org.uk,
	cmm@...ibm.com, tytso@....edu, marco.stornelli@...il.com,
	stroetmann@...olinux.com, diegocg@...il.com, chris@...muel.org,
	Zhi Yong Wu <wuzhy@...ux.vnet.ibm.com>
Subject: Re: [RFC v2 02/10] vfs: add support for updating access frequency

On Thu, Sep 27, 2012 at 10:19 AM, Dave Chinner <david@...morbit.com> wrote:
> On Wed, Sep 26, 2012 at 10:53:07AM +0800, Zhi Yong Wu wrote:
>> On Tue, Sep 25, 2012 at 5:17 PM, Dave Chinner <david@...morbit.com> wrote:
>> > On Sun, Sep 23, 2012 at 08:56:27PM +0800, zwu.kernel@...il.com wrote:
>> > I note that the code will always insert range items of a length
>> > RANGE_SIZE. This means you have a fixed object granularity and hence
>> > you have no need for a range based search. That is, you could use a
>> > radix tree where each entry in the radix tree points directly to the
>> > range object similar to how the page cache uses a radix tree for
>> > indexing pages. That brings the possibility of lockless range item
>> > lookups....
>> Great suggestion, but can we temporarily put it in TODO list? because
>> it will bring one big code change.
>
> Sure. I just wanted to point out that there are better choices for
> indexing fixed size elements than rb-trees and why it might make
> sense to use a different type of tree.
Got it, thanks. Moreover, it should also be better to use radix tree
to hold hot_inode, not only hot_range.

>
> Cheers,
>
> Dave.
> --
> Dave Chinner
> david@...morbit.com



-- 
Regards,

Zhi Yong Wu
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