On 9/6/08, Linus Torvalds  wrote:

quoted text
>  I'm starting to hate zlib. I actually spent almost a week trying to clean

>  up the zlib source code and make it something that gcc can compile into

>  clean code, but the fact is, zlib isn't amenable to that. The whole "shift

>   bits in from the buffer" approach means that there is no way to make

>  zlib generate good code unless you are an insanely competent assembly

>  hacker or have tons of registers to keep all the temporaries live in.

>

>  Now, I still do think that all my reasons for choosing zlib were pretty

>  solid (it's a well-tested piece of code and it is _everywhere_ and easy to

>  use), but boy do I wish there had been alternatives.

Some alternative algorithms are here...

http://cs.fit.edu/~mmahoney/compression

It is possible to beat zlib by 2x at the cost of CPU time and memory.
Of course switching to these algorithms would involve a lot of testing

and benchmarking. I'm also not sure how PAQ would fare on lots of

small git objects instead of large files.
Turning a 500MB packfile into a 250MB has lots of advantages in IO

reduction so it is worth some CPU/memory to create it.
You can even win 50'000€ for a better algorithm.

http://prize.hutter1.net/
--

Jon Smirl

jonsmirl@gmail.com

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