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Re: multi threaded support for xz

On 2016-10-06 02:50:00 [+0000], HW42 wrote:
> Is the new multi-thread compressor reproducible? I.e. does it produce
> the same output regardless of the number of CPUs, the CPU speed, system
> load, etc.? (A very quick look at the source suggest that this is not
> the case but I might be totally mistaken)

With one CPU you have one block. With multiple CPUs the default block
size (as of current xz) is dictionary size * three. So it is
reproducible as long as you use one or multiple CPUs.
In order to have the same compressed archive with one or multiple CPUs
you would need a switch / environment variable to disable the use of
multiple CPUs.


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