On Wed, Jul 22, 2009 at 03:28:09PM +0000, kevin.granade@xxxxxxxxx wrote : > On Jul 22, 2009 9:01am, Albin Tonnerre <albin.tonnerre@xxxxxxxxxxxxxxxxxx> > wrote: > > This is the first part of the lzo patch > > > > The lzo compressor is worse than gzip at compression, but faster at > > > > extraction. Here are some figures for an ARM board I'm working on: > > > > > > > > Uncompressed size: 3.24Mo > > > > gzip 1.61Mo 0.72s > > > > lzo 1.75Mo 0.48s > > > > > > > > So for a compression ratio that is still relatively close to gzip, it's > > > > much faster to extract, at least in that case. > > Is that "time to run the extraction algorithm", or "time to read in image from > media and extract"? I think the time to read from the media would tend to > dominate the decompression time. > Either way, could you provide the other time for each algorithm in order to > give a sense of how this might scale to other CPU speeds/media read speeds? > That's the time to run the extraction algorithm. As H. Peter Anvin pointed out, you can have a fast media and a somewhat slow CPU, for which lzo makes sense. As for other data, I don't have all the figures handy, but: - LZMA: compressed size 1.19Mo, decompression time: several *seconds* (that's on a 180MHz ARM9 board, using a patch to implement LZMA compression similar to this one) - Bzip2 eats a lot of RAM, and head.S only gives 64Ko of malloc() space on ARM, so I didn't try. Regards, -- Albin Tonnerre, Free Electrons Kernel, drivers and embedded Linux development, consulting, training and support. http://free-electrons.com
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