Off topic - G5 question

Mark Hahn hahn at physics.mcmaster.ca
Wed Jun 25 20:20:00 EDT 2003


> Hi you all guys, I've just checked the G5 processor out, what do you 
> think about it, it seems like it's not good enough considering it's 
> architecture and it's performance.
> 
> http://www.apple.com/lae/g5

it's a nice step forward for Apple - the first time they've 
actually taken dram seriously.

but Apple drinks a little too much of their own koolaid,
or at least gives their marketing weasels a little too much leash.

if you haven't looked already, Apple paid one of those analyst 
companies (Veritest, nice name) to prove that the G5 spanks 
those unwashed, beige-boxed, Intel-using heathens.
to accomplish this, they tuned the G5 quite nicely, 
and relentlessly de-tuned the PC - stopping just short of 
installing WinME on it ;)

if you want to make your competition look bad, run their benchmarks for them.

at a glance, it might seem sensible to use gcc 3.3 for both machines;
as Veritest says:
	To be able to directly compare the performance 
	of the hardware systems, the same compiler - 
	GCC, with similar settings were used on both platforms.  

OK, well, first of all, even if you build gcc 3.3 from scratch on each 
system, it's not going to factor out compiler effects.  gcc does slightly
different things on each platform.  next, they didn't actually use the 
same compiler - they used Apple's gcc 3.3 binary, and for the PC, one 
build from virgin sources.  all of this begs the question of why they 
wouldn't use Intel's compilers, which for some old reason, do really
well on SPEC sources...

it gets worse.  things like tuning the dual-G5 to avoid snoop traffic
when running (uniprocessor) CPU2000 tests, but turning *on* HT on the 
(uniprocessor) P4, and running an SMP kernel.  again, there's a nugget
of plausibility there, since they presumably couldn't get a uniprocessor
version of Mac OS X.  sure enough: they turn HT off and install a uni kernel
to test SPEC rate on the uniprocessor and disable HT on the SMP system.

quite different compiler switches for the two platforms, as well.

don't forget to install a special single-threaded malloc, but only 
for the uniprocessor G5 tests...

they appear to be trying to make a same-to-same comparison, which 
is both difficult and strange.  users want a best-to-best comparison.

_______________________________________________
Beowulf mailing list, Beowulf at beowulf.org
To change your subscription (digest mode or unsubscribe) visit http://www.beowulf.org/mailman/listinfo/beowulf



More information about the Beowulf mailing list