[Pw_forum] a problem with 64-bit OS by multiprocess calculation

[Alexej Mazheika]

>
> i don't think that this is a strange phenomenon at all.
> in general, a 64-bit compilation of a code should be expected
> to be slower than a 32-bit compilation. all memory pointers
> are twice the size and thus require more memory bandwidth and
> incur a reduced cache efficiency.
>
> only, it usually doesn't show so much on x86_64 since the 32-bit
> x86 cpu design is to horribly register starved and AMD doubled
> the number of registers to make up for it. however, if your job
> runs only for a few minutes then you may still see the additional
> overhead from the larger pointers. for a larger problem, that
> should be reduced. if not, there may be different compilers or
> compiler settings.
>
> on non-x86 CPUs a 64-bit mode compilation on codes like Q-E
> is typically about 10-20% slower than a 32-bit compile.
>
> cheers,
> axel.
>

Thank you for explaination of the reason of my problem. The time-difference
is not so much, so I think I won't undertake anything. With various compiler
settings I experimented by compilation but it didn't bring any considerable
results.

regards,
Alex
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