32-bit or 64-bit

Chris Jones jonesc at hep.phy.cam.ac.uk
Fri Jun 5 17:19:00 UTC 2009

> It does; 64-bit is a lot faster, especially for media conversion (don't 
> know why exactly, but it's the case).

The reason is when building source code, the compiler has to accommodate 
all platforms that are available. As 64 bit processors are a lot newer 
than 32 bit ones, the compiler is able to use features in 64 bit mode it 
cannot in 32 bit mode.

For instance SSE instructions - The compiler knows that *all* 64 bit 
machines have these, so it can safely use them to speed up various math 
routines. It cannot do this in 32 bit mode, as not all 32 bit processors 
support these. This can make a difference, particularly in heavy number 
crunching (i.e. media conversion).

cheers Chris

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