[PD] tabread / write broken on 64bit AMD Linux

[Miller Puckette]

The bad thing about 64 bit computing is that 64-bit programs tend to
use more memory bandwidth than 32-bit ones, so that you would expect
a processor to spend more time waiting for memory in 64 bit mode than
32.  This could easily outweigh the register-count advantage of AMD64
in running Pd.  I'm planning to get an AMD64 box in another month or so
and should know more then... given the high prices of 64 bit machines,
it might be smary to wait until we can get an actual speed comparison
before spending the dough.

cheers
Miller


On Sat, Mar 25, 2006 at 07:59:24AM +0000, carmen wrote:
> > Well, I was going to do it, but we figured out that 64-bit wasn't worth
> > the trouble yet. It's not that much worth it until standard PCs ship with
> > well over 4G RAM.
> 
> Ron Kuper sez 'no'... http://www.cakewalk.com/x64/whitepaper.asp
> 
> " the CPU has twice the general purpose registers and twice the floating point unit (FPU) registers, compared to x86 processors.  And each general purpose register is also twice as wide, 64 bits instead of 32 bits."
> 
> "For a specific example of why this matters, consider a digital equalizer.  The math involved in computing equalization usually involves a processing element known as a "biquad".  A biquad is a small code fragment that manipulates 8 numeric values in a series of additions and multiplications.  The x86 floating point unit has a total of 8 registers, so even something as simple as 1 biquad will use up all of its registers. "
> 
> > Apparently there are other advantages to the 64-bit
> > mode, but I've not witnessed any difference with the programs that I use.  
> > And then many programs' RAM usage might nearly double, especially programs
> > that use lots of pointers
> 
> it is almost 2x, from what i recall, but having finally replaced the last Celeron here with a Sempron64, i can't double check..
> 
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