Datastore profiling

[NoiseEHC]

The best would be writing with LZO and later recompress with ZLIB. Also 
the clear install image (which is created in the build) should use the 
slowest ZLIB compression, but I am not sure if this latest idea worths 
implementing.

Erik, you asked how long would it take to finish my decompression 
routines. I did not answer since I was not sure but now it is 100% that 
it will no go into 8.2.0 (currently I am working 12+ hours and could not 
switch on my XO for a week...)

Erik Garrison wrote:
> On Wed, Aug 13, 2008 at 06:06:03PM +0200, Tomeu Vizoso wrote:
>   
>> On Wed, Aug 13, 2008 at 5:51 PM, Erik Garrison <erik at laptop.org> wrote:
>>     
>>> On Wed, Aug 13, 2008 at 11:41:38AM +0200, Tomeu Vizoso wrote:
>>>       
>>>> In most cases, the files that activities put into the DS are moved
>>>> instead of copied, because of the long time that takes writing to
>>>> jffs2 due to compression. That will change the profiling results a
>>>> lot.
>>>>         
>>> I'm working on the jffs2 compression issue.  Compression algorithm
>>> support could greatly improve system i/o performance.
>>>       
>> That looks interesting, but from my POV, would be better for Sugar
>> performance if compression was disabled by default, and was mostly
>> used just by pilgrim when creating the jffs2 image file.
>>     
>
> In July, NoiseEHC reported results from his testing of lzo and zlib
> compression.  To best estimate the results we should expect from
> implementing filesystem-wide compression, he compiled the kernel zlib
> and lzo in userspace to test their performance.  Please refer to
> http://lists.laptop.org/pipermail/devel/2008-July/016956.html
>
> I do not understand why we wouldn't want to accept a >500% increase in
> write performance and a >300% read performance boost at the cost of a
> ~25% increase in the size of compressed data.  Please clarify your POV.
>
> Erik
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