[kde-solaris] Solaris + GCC -> -m32 or -m64 ??

Nick THOMPSON nickthompson at agere.com
Thu Feb 5 15:27:17 CET 2004


(Game console myth number 56: more bits = more speed)

I don't have any direct experience of KDE with 64 bits, but more bits
doesn't equal more speed. In fact you are likely to find a slowing down
due to the larger instructions that will have to get through your
processor. The only reason to consider more bits is when you have huge
data and/or RAM (>4GB) to manipulate and you need the bigger pointer or
offsets that are then possible. As you only have 256MB of RAM, there is
no obvious need for 64 bits.

Taking the ARM uC as an example, 16bit (thumb) mode was invented to
_increase_ the speed of this 32bit processor. This works because there
are less instruction bits to read from memory. In general you need more
instruction to make up for the inherent lack of flexibility of
instructions in 16bit mode, but not so many more as to lose everything
you have gained in instruction bandwidth.

Signal processing and maths functions can occasionally benefit from a
few more bits if you have some good instructions (and software) to make
use of them.


On Thu, 2004-02-05 at 13:16, Jan Van Belle wrote:
>     Hello all,
>     I am trying to build a 64 bit toolchain for solaris2.8, in order to 
> compile the new KDE-3.2.0
> Any hints?? (I am following the LFS way of making my toolchain)
> Is it really worth it (I mean: the trouble of going from 32 bit to 64). 
> Is there a noticeable change in speed?? I have a 400MHz Ultra5 with 
> 256MB RAM.

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