# Re: Building packages three times in a row

On Mon, Sep 24, 2007 at 08:35:50PM +0200, Goswin von Brederlow wrote:
>
> Some tools use randomization to get out of worst case situations or
> general optimization. For example when you look for an optimal
> allocation of register usage you can do a search by picking a random
> register allocation and repeat that a few thousand times to find a
> suitable minimum.
>
> Or a randomized heap that gives you O(1) time for
> all operations instead of O(lg n).
>
> By requiring bit-to-bit identical results you eliminate all such
> randomness and could seriously hinder the algorithm available for
> tools.
While I have a hard time understanding why true randomness is
required to solve such problems, I have no problem accepting that
practically this is a big obstacle.
It will not be trivial to establish the equivalence of two such
pieces of object code.
Thank you for sharing this insight. I think you have helped me to
finally see the problem that others have pointed to.
Taking etch as the example, could you give any idea what percentage
of package we might expect this to turn up in ?
In any case it sounds very much like this idea would be much harder
to do than I had originally hoped :-(
Regards,
Paddy

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