compression tests in jffs2

compression tests in jffs2

[Matías Zabaljáuregui]

Hello, I'm interested in doing some tests on jffs2 compression  
algorithms (CPU, RAM, and compression ratio), and I've two questions:

- recompiling the jffs2 module is the only way to reconfigure the  
compression behaviour?

- Is there any documentation about using comprtest.c ?

thank you in advance

----------------------------------------------------------------------------------
Matías Zabaljáuregui
http://linux.linti.unlp.edu.ar






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Re: compression tests in jffs2

[Artem Bityutskiy]

Hi Matías,

On Fri, 2006-11-17 at 19:06 -0300, Matías Zabaljáuregui wrote:
> Hello, I'm interested in doing some tests on jffs2 compression  
> algorithms (CPU, RAM, and compression ratio), and I've two questions:

sounds promising!

> - recompiling the jffs2 module is the only way to reconfigure the  
> compression behaviour?

Yes at the moment. But adding dynamic and per-file compression so would
cool.

> - Is there any documentation about using comprtest.c ?

Unfortunately no. There are not a lot of JFFS2 documentation. You'll
need to dig the sources which are somewhat not very easy to dig. Feel
free to ask questions.

-- 
Best regards,
Artem Bityutskiy (Битюцкий Артём)

Re: compression tests in jffs2

[Matías Zabaljáuregui]

OK! Thank you for your answer

>
>> - recompiling the jffs2 module is the only way to reconfigure the
>> compression behaviour?
>
> Yes at the moment. But adding dynamic and per-file compression so would
> cool.
>

Do you think a /proc entry is a suitable mecanism for runtime  
compression configuration?


-------------------------------------
Matías Zabaljáuregui
linux.linti.unlp.edu.ar

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Re: compression tests in jffs2

[Josh Boyer]

On Sat, 2006-11-18 at 13:35 -0300, Matías Zabaljáuregui wrote:
> OK! Thank you for your answer
> 
> >
> >> - recompiling the jffs2 module is the only way to reconfigure the
> >> compression behaviour?
> >
> > Yes at the moment. But adding dynamic and per-file compression so would
> > cool.
> >
> 
> Do you think a /proc entry is a suitable mecanism for runtime  
> compression configuration?

Please avoid /proc for anything.  The compression type has nothing to do
with processes, so it doesn't belong in /proc.

I would suggest either using a mount option if you want to make the
whole filesystem use a particular type of compression, or use xattrs to
specify compression type on a per file basis.  A third option would be
to use a sysfs entry similar to how you would use /proc.

josh

Re: compression tests in jffs2

[Matías Zabaljáuregui]

yes, I know... thank you for the advice.

In compr.c file, I can see some "stats" and "compression-mode" getters  
and setters, between  CONFIG_JFFS2_PROC  #ifdef and #endif... Do you  
think it is posible to reuse this code for implementing a sysfs  
interface?


----------------------------------------------------------------------------------
Matías Zabaljáuregui
http://linux.linti.unlp.edu.ar



Quoting Josh Boyer <jwboyer@linux.vnet.ibm.com>:

> On Sat, 2006-11-18 at 13:35 -0300, Matías Zabaljáuregui wrote:
>> OK! Thank you for your answer
>>
>> >
>> >> - recompiling the jffs2 module is the only way to reconfigure the
>> >> compression behaviour?
>> >
>> > Yes at the moment. But adding dynamic and per-file compression so would
>> > cool.
>> >
>>
>> Do you think a /proc entry is a suitable mecanism for runtime
>> compression configuration?
>
> Please avoid /proc for anything.  The compression type has nothing to do
> with processes, so it doesn't belong in /proc.
>
> I would suggest either using a mount option if you want to make the
> whole filesystem use a particular type of compression, or use xattrs to
> specify compression type on a per file basis.  A third option would be
> to use a sysfs entry similar to how you would use /proc.
>
> josh
>
>
>



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