[POLLING] strange interrupt/system load

[peterjeremy at acm.org]

On 2009-Sep-13 07:19:24 -0700, Barney Cordoba <barney_cordoba at yahoo.com> wrote:
>64bits must be faster than 32bits is patently misguided. My rule of 
>thumb is that if I don't need 64bits for something, I avoid it.

It's not quite that cut-and-dry.  The 64-bit ISA is significantly
different to the 32-bit ISA and has different subroutine calling
conventions.  Yes, you do need to lug 64-bit pointers around but the
overall codesize is comparable (looking at /usr/bin and /lib suggests
about a 5% increase in size going from i386 to amd64) - a lot of this
is probably because amd64 has a 16-bit offset mode so there's much
less need for 32-bit offsets.  Having twice as many registers is a
win in some areas (less spilling to memory) and a loss in others (more
state to save/restore on a context switch).

If performance is critical, it's probably worthwhile benchmarking
both i386 and amd64 variants and seeing which works best for you.

-- 
Peter Jeremy
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