idea about internal fragmentation in Btrfs

idea about internal fragmentation in Btrfs

[Zhihui Zhang]

I wish Btrfs well, so I would venture an idea for this specific case
mentioned by Edward Shishkin today.

Everyone knows that B-tree has internal and leaf nodes.  Can we make
the root as the leaf?  In other words, if you
create a 2K file, the B-tree will have only one node, which is both
the root and the leaf. Of course, you need some flag to
say this is a "degenerated" form of B-tree. Please cc me if you want
my response.

thanks,

-Zhihui

Re: idea about internal fragmentation in Btrfs

[Andi Kleen]

Zhihui Zhang <zzhsuny@gmail.com> writes:

> I wish Btrfs well, so I would venture an idea for this specific case
> mentioned by Edward Shishkin today.
>
> Everyone knows that B-tree has internal and leaf nodes.  Can we make
> the root as the leaf?  In other words, if you
> create a 2K file, the B-tree will have only one node, which is both
> the root and the leaf. Of course, you need some flag to
> say this is a "degenerated" form of B-tree. Please cc me if you want
> my response.

You need to copy linux-btrfs to reach btrfs developers.
Ccs added

The problem with your idea is that on btrfs there's only 
a single tree for the whole fs (or whole snapshot rather)
So it would only work for a single file because there's
only a single root.

-Andi
-- 
ak@linux.intel.com -- Speaking for myself only.

Re: idea about internal fragmentation in Btrfs

[Zhihui Zhang]

Makes perfect sense. No wonder some btrfs folks used to work on
reiserfs/4. I hope a solution can be or has been found.

On Sat, Jun 19, 2010 at 4:51 PM, Andi Kleen <andi@firstfloor.org> wrote=
:
> Zhihui Zhang <zzhsuny@gmail.com> writes:
>
>> I wish Btrfs well, so I would venture an idea for this specific case
>> mentioned by Edward Shishkin today.
>>
>> Everyone knows that B-tree has internal and leaf nodes. =A0Can we ma=
ke
>> the root as the leaf? =A0In other words, if you
>> create a 2K file, the B-tree will have only one node, which is both
>> the root and the leaf. Of course, you need some flag to
>> say this is a "degenerated" form of B-tree. Please cc me if you want
>> my response.
>
> You need to copy linux-btrfs to reach btrfs developers.
> Ccs added
>
> The problem with your idea is that on btrfs there's only
> a single tree for the whole fs (or whole snapshot rather)
> So it would only work for a single file because there's
> only a single root.
>
> -Andi
> --
> ak@linux.intel.com -- Speaking for myself only.
>
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Re: idea about internal fragmentation in Btrfs

[Zhihui Zhang]

Makes perfect sense. No wonder some btrfs folks used to work on
reiserfs/4. I hope a solution can be or has been found.

On Sat, Jun 19, 2010 at 4:51 PM, Andi Kleen <andi@firstfloor.org> wrote:
> Zhihui Zhang <zzhsuny@gmail.com> writes:
>
>> I wish Btrfs well, so I would venture an idea for this specific case
>> mentioned by Edward Shishkin today.
>>
>> Everyone knows that B-tree has internal and leaf nodes.  Can we make
>> the root as the leaf?  In other words, if you
>> create a 2K file, the B-tree will have only one node, which is both
>> the root and the leaf. Of course, you need some flag to
>> say this is a "degenerated" form of B-tree. Please cc me if you want
>> my response.
>
> You need to copy linux-btrfs to reach btrfs developers.
> Ccs added
>
> The problem with your idea is that on btrfs there's only
> a single tree for the whole fs (or whole snapshot rather)
> So it would only work for a single file because there's
> only a single root.
>
> -Andi
> --
> ak@linux.intel.com -- Speaking for myself only.
>