[geeks] 64-bit apps vs. 32-bit apps

[Doug McLaren]

On Fri, Dec 29, 2006 at 03:14:54PM -0600, Jonathan C. Patschke wrote:

| Then, it's up to you to determine a decent benchmark.  I found, for
| example, that whatever version of gzip I was running at the time
| performed the same whether built n32 or n64 on my Octane, but was
| significantly faster built -xarch=v9 -xtarget=ultra on my Ultra 1e than
| with the compiler defaults.

gzip comes with assembly language cores for several architectures, so
it doesn't make a very good benchmark of compiler options unless you
make sure to compile it with the asm core disabled.

These cores can make a huge difference -- I recall gzip being roughly
30x faster (seriously!) on a p2/300 I had vs. the 133 MHz PPC RS/6000
I had at the time.  Yes, the PC's cpu was probably at least 3x faster,
but the assembly code used in the x86 version vs. the C code used in
the PPC version made a huge difference as well.

(And of course, the assembly code probably doesn't care what compiler
options or modes you use.  The rest of gzip might be faster, but that
core probably won't care.)

-- 
Doug McLaren, dougmc at frenzied.us
If Barbie is so popular, why do you have to buy all of her friends?