Re: [isabelle] 32 vs. 64 bit

> I don't have a deep knowledge of the
> Poly/ML implementation but my understanding is that, while the 64-bit
> version uses more memory to accomplish the same
> thing, you *must* use it if you want to use more than N bytes of RAM
> (for some N; 4GB?).

As far as I understand it, the 32 bit reduces heap requirements in the
first place. Also, it gives better performance. For example, AODV with
threads=8 takes 1h39m on 64 bit, but just 1h20m on 32 bit.*

As an interesting side note: I've found that under low memory pressure,
that session may reserve north of 50 GB memory (using 64 bit), but it is
also fine to run with less than 4 GB (using 32 bit). My initial
suspicion that 64 bit might be faster for huge sessions by reducing GC
time turned out to be false.


* This thread also reminded me that I haven't yet installed the 32 bit
libraries on the Jenkins nodes.

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