[linux-audio-user] 64bit vs 32bit (was: Re: AMD64 question: update)

Roberto Gordo Saez roberto.gordo at gmail.com
Wed Jul 12 11:04:35 EDT 2006

On 7/11/06, Arnold Krille <arnold.krille at gmail.com> wrote:
> Well, I _know_ that 64bit is faster: Here at work I have dual-Xeon's
> with 2.8GHz, my laptop is a Turion64 with 1.8GHz. The same computation
> (evaluating scientific data from time-of-flight/lifetime experiments)
> on the same data-files is significant slower on the work-pc's (almost
> factor 2). As my threads are one thread for computation and others for
> loading and saving the data, it is really a comparison of two single
> processors, where the faster one does even the IO-work itself...

Personally, I would like to suggest everyone to actually make some
serious tests on 64bit hardware with some intensive sound applications
(or other programs that are main tasks for the computer). Latter, you
can decide which one you want for everyday use.

Surprisingly for myself, I've found that 64bit are NOT always much
faster, and sometimes are actually slower. It is true that most
applications may improve performance when running on 64bit. But
exceptions does exist, mainly because the smaller data chunks on code
with 4 byte pointers (32bit), which improves cache usage, and also
because there are still lots of applications heavily optimized for
32bit x86 code, whose performance is degraded when running on 64bit.

I've made tests mainly on big server applications, I have not made
tests on audio software, so I suggest everyone to dedicate some time
testing your own apps. It is simple: make two partitions, one of them
with a 32bit OS, and the other optimized for 64 bit. Do not use a
chroot nor mixed environment (32bit libs on 64bit system), because the
results can be slightly different.

There is one case in that 64bit is always recommended: if you want to
use big resource hungry applications that handle more than 3GB of RAM
per process. Linux does support more RAM even on 32bit machines (using
PAE extension), but the ugly limit on memory per process on 32bit mode
is still there. On 64bit mode processes can access up to 1TB. And yes,
they actually exists. I've seen some applications easy allocating more
than 50GB of RAM per process! But not on my main desktop computer, it
is still a Pentium II :-)

I'm interested on this, so if anyone has made some real performance
tests with commonly used audio or other multimedia apps on 32bit and
64bit, it would be great to know results.

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