Mailinglist Archive: opensuse (686 mails)

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Re: [opensuse] 64 bit vs 32 bit RAM consumption
On 7/23/2013 5:44 AM, Carlos E. R. wrote:
If the programmer knows the maximum value of a variable (if he doesn't, he
guesses and sets a limit), he may choose the smaller variable
needed to hold it (the other criteria is the one that is faster to access for
the architecture). Or he may simply choose a default value,
like "integer".

However, when the application was designed for 32 bit and then is re-compiled
for 64, it may well happen that the size of the variable types
chosen may shift from 32 to 64 bit - thus automatically the size of those
variables increase to double.

If that data space is large, the impact can be significant.

Except that the impact isn't likely to be significant at all.

The overwhelmingly vast majority of data in any system is not concerned with an
integer here or
a float there. The bulk of data, by a wide margin, is a string, or a block of
text.
In that world, a byte is still a byte.

With bigger registers you can move data twice as fast, because the load time
for 32 bits is
the same for 64 bits.

The programs instructions, your code pages, is the thing that might grow the
most.
Presumably most of that is optimized, but I really don't know for sure.


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