Re: Which 64bit debian version for Intel(R) Core Quad Processor Q8300?
On Sun, 29 May 2011 12:43:36 +0200
Goswin von Brederlow <goswin-v-b@web.de> wrote:
> > The only reservation I'd have about that is if you're going to be using
> > huge programs written in Scheme. That's pointer-heavy, and will use
> > about twoce as much RAM to accomplish the same thing in 64-bit more as
> > 32-bit mode. Unless you have more than about 6gig of RAM, whereupon
> > 64-bit is a win again.
Are you really sure of that 2x increase when going from 32bits to
64bits in RAM usage? My feeling (and old experiment with Ocaml code, or
with the GCC compiler itself - which mostly do symbolic processing,
like every compiler) is that the memory footprint indeed increased, but
more with a 1.5x factor than a 2x factor. Assuming C code, sizeof(int)
is still 4 bytes on both 32 and 64 bits x86, but sizeof(long) and sizeof
(void*) goes from 4 to 8 bytes
And going to 64bits system might sometimes be a win, at least in speed,
because the AMD64 instruction set has 16 registers (but x86 in 32 bits
= ia-32 has only 8). This avoid lots of registers spill to memory. I
believe the usual win in speed is about 5-15% (for the same program
operating on the same input files, when going from 32 bits to 64 bits).
And if you have more than 3Gb of RAM (which is quite common today),
going to a 64 bits system may enable you to process more data, because
you can have a single big process which consumes nearly all your RAM
(if you have 6Gb RAM, you cannot have a 5Gb process in 32 bits, but you
can have it in 64 bits).
So I still suggest installing a 64 bits Debian distribution if you have
a 64 bits x86-64 (or AMD64) processor with at least 4Gb RAM.
BTW, some non free programs (e.g. Adobe flashplayer) may be available
only in 32 bits.
And a 64 bits distribution can run 32 bits programs (you'll need to
install some specific packages to enable that).
Regards
--
Basile STARYNKEVITCH http://starynkevitch.net/Basile/
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