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

From: Juan Piernas Canovas
Date: Sun Feb 25 2007 - 22:49:10 EST


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@xxxxxxxxxxx
PGP public key:
http://pgp.rediris.es:11371/pks/lookup?search=piernas%40ditec.um.es&op=index

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