LZO support

NoiseEHC NoiseEHC at freemail.hu
Sun Jul 20 04:57:37 EDT 2008

Okay, I have become a little more advanced lately, and was able to 
compile the kernel zlib and lzo in userspace (last year I gave up...).

So here is the code (with results, the lib file is the compiled lzo 2.03):

Since I did not find any assembly compressor support (only 
decompressor), I do not know what did I talked about last time. It could 
have been that I have been dreaming about that...

The program needs a test.dat file, I have used "cat */*>test.dat" in 
"/var/lib" which gave me a 22 MB file (the code handles a max of 40 MB). 
The results are consistent with Erik's results. Since ZLIB has a 
compression level parameter, and LZO has different compressor types, I 
will test those as well.

Now I think that jffs2 (or any other flash filesystem) should use LZO to 
store the data, so if the limit is the flash write speed then it could 
write twice as fast. Later, when there is ample power in the battery and 
no cpu utilization, it should recompress the data either using a better 
LZO or by ZLIB (of course only those files which are old enough, so it 
would not recompress files which will be modified soon).

And the results:
started with block size == 4096

LZO test
in size: 22987994
22987994 -> 11575529 (50.354672%)
1.960000 seconds -> 11.185234 MB/sec
11575529 -> 22987994
0.750000 seconds -> 29.230745 MB/sec
compared 22987994 bytes OK

LZO asm test
in size: 22987994
22987994 -> 11575529 (50.354672%)
1.930000 seconds -> 11.359098 MB/sec
11575529 -> 22987994
0.490000 seconds -> 44.740936 MB/sec
compared 22987994 bytes OK

ZLIB test
in size: 22987994
22987994 -> 8982973 (39.076802%)
9.810000 seconds -> 2.234767 MB/sec
8982973 -> 22987994
2.750000 seconds -> 7.972022 MB/sec
compared 22987994 bytes OK

Greg Smith wrote:
> Hi Erik,
> Can you design a test case or two to test the performance of these 
> compression schemes?
> Thanks,
> Greg S
> _______________________________________________
> Devel mailing list
> Devel at lists.laptop.org
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