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Re: Fedora 9 32 or 64 Bit - Which One?



Matthew Flaschen wrote:
stan wrote:
Alan Cox wrote:
On Mon, 27 Oct 2008 11:54:47 -0400
Matthew Flaschen <matthew flaschen gatech edu> wrote:

Alan Cox wrote:

The moment you have more than about 900MB of RAM there are big
advantages
to running a 64bit kernel as it can keep all of physical and virtual
space mapped at the same time, which is a big performance win.

Alan
Wouldn't you need twice as much memory to have the same memory for
applications if you are using double the word size?

This is incorrect in general.  GNU/Linux 32-bit uses ILP32, meaning
integers, longs, and pointers all have 32 bits.  GNU/Linux 64 uses LP64,
which means longs and pointers have 64 bits.  Integers remain 32 bits,
and ASCII chars are still 8 bits (this is true of ILP64, another model,
as well).  Please read http://www.unix.org/whitepapers/64bit.html.

Thank you for the response and the link.


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