Re: [ANNOUNCE] DualFS: File System with Meta-data and Data Separation

From: Juan Piernas Canovas <piernas@ditec.um.es>
To: "Jörn Engel" <joern@lazybastard.org>
Cc: Sorin Faibish <sfaibish@emc.com>,
	kernel list <linux-kernel@vger.kernel.org>
Subject: Re: [ANNOUNCE] DualFS: File System with Meta-data and Data Separation
Date: Mon, 26 Feb 2007 04:48:51 +0100 (CET)	[thread overview]
Message-ID: <Pine.LNX.4.61.0702260442030.25255@ditec.inf.um.es> (raw)
In-Reply-To: <20070225120138.GA19047@lazybastard.org>

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On Sun, 25 Feb 2007, [utf-8] Jörn Engel wrote:

> On Sun, 25 February 2007 03:41:40 +0100, Juan Piernas Canovas wrote:
>>
>> Well, our experimental results say another thing. As I have said, the
>> greatest part of the files are written at once, so their meta-data blocks
>> are together on disk. This allows DualFS to implement an explicit
>> prefetching of meta-data blocks which is quite effective, specially when
>> there are several processes reading from disk at the same time.
>>
>> On the other hand, DualFS also implements an on-line meta-data relocation
>> mechanism which can help to improve meta-data prefetching, and garbage
>> collection.
>>
>> Obviously, there can be some slow-growing files that can produce some
>> garbage, but they do not hurt the overall performance of the file system.
>
> Well, my concerns about the design have gone.  There remain some
> concerns about the source code and I hope they will disappear just as
> fast. :)
>
This is a bit more complicated ;)

> Obviously, a patch against 2.4.x is fairly useless.  Iirc, you claimed
> somewhere to have a patch against 2.6.11, but I was unable to find that.
> Porting 2.6.11 to 2.6.20 should be simple enough.

I'm working on a public patch of DualFS for Linux 2.6.x. It's a matter of 
time.

>
> Then there is some assembly code inside the patch that you seem to have
> copied from some other project.  I would be surprised if that is really
> required.  If you can replace it with C code, please do.
>
> If the assembly actually is a performance gain (and I consider it your
> duty to prove that), you can have a two-patch series with the first
> introducing DualFS and the second adding the assembly as a config option
> for one architecture.
>
No problem. I will see if the assembly code can be replaced with bare C.

Regards,

 	Juan.
-- 
D. Juan Piernas Cánovas
Departamento de Ingeniería y Tecnología de Computadores
Facultad de Informática. Universidad de Murcia
Campus de Espinardo - 30080 Murcia (SPAIN)
Tel.: +34968367657    Fax: +34968364151
email: piernas@ditec.um.es
PGP public key:
http://pgp.rediris.es:11371/pks/lookup?search=piernas%40ditec.um.es&op=index

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