[PD] more about float limitation

[IOhannes m zmölnig]

On 02/01/2015 06:05 PM, Alexandre Torres Porres wrote:
>>
>> Seems Pd runs faster if compiled to 64 bits in a 64 bit OS than if it were
>> compiled as 32, which does makes sense. That's all?
>>
> 
> "*no : pd compiled for 64 bit system will not run on 32 bit sytem, and it
> will not load 32 bit externals.*"
> 
> sure, but it still runs faster if compiled to 64 bits in a 64 bit OS, right?
> 

why?

if you run a 32bit binary on a 64bit OS, there might be some overhead
involved (bit then i really don't know much about the performance of
multi-arch systems)

if you run a 32bit binary on a 32bit OS on a 64bit CPU (x86_64, which is
compatible with 32bit CPUs), then it might be slightly slower than
compared to a full 64bit system.


the real advantages are:
- memory access!
 a 32bit application/OS uses 32bit pointers to access memory. this
limits the accessible memory to 4GB (your OS might be able to manage
more using PAE; but the application itself will have a maximum of 4GB.)
 a 64bit application uses 64bit pointers to access memory. thats much
more as you are likely to ever see in your lifetime (but then: 2640k are
enough" anybody?)

- modern OSs are 64bit (even the not-so-modern w32[sic!] has started to
become a 64bit system).
it seems silly to run 32bit applications on such systems (and a waste of
ressources, as you need to install a 32bit version the entire
runtime-environment)


also check out: http://en.wikipedia.org/wiki/64-bit_computing

fgrsam
IOhannes

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