On 24/05/2020 07:34, Richard Kettlewell wrote:
> Deloptes  writes:
>> Jörg W. wrote:
>>> Usually the OS is 32-Bit. 64-Bit would slow down the programms by
>>> using a lot of space for bytes filled with zero.
>
> AFAIK Linux does not support 64-bit applications running on a 32-bit
> kernel.
>
>> I was thinking the opposite. If it were 64 bit it would boost the
>> processing.
>
> Often yes. In both ARM and x86, the 64-bit instruction set has twice as
> many general-purpose registers as the 32-bit one, improving performance
> for some code. Anything that deals with quantities larger than 32 bits
> will also have a performance boost.
>
>> Why should a program be slower processing on 64 than on 32?
>> Emptiness does not slow down anything or am I wrong?
>
> Pointers are twice the size, meaning they have higher average memory
> access costs (more cache misses, lower throughput to RAM). So a very
> pointer-heavy program might have reduced performance when recompiled for
> 64 bits.
>

Also in the case of Intel x86 vs AMD64 the code is also often a bit
bigger for the 64 bit version of a program which means the processor
reads it a little slower and less of it will fit in any memory cache or
instruction cache.

I don't know if the same applies to ARM or not.

--
Brian Gregory (in England).

--- SoupGate-Win32 v1.05