[Beowulf] G5 beowulf cluster

Mark Hahn hahn at physics.mcmaster.ca
Tue Feb 8 11:26:32 PST 2005

> Hello, we, at the physics institute in Mexico have got four Xserve G5
> and we would like to use them as a beowulf, my first doubt is about what
> operating system to use, we've been using linux for our other clusters,

I would strongly encourage you to try both Linux and Mac OS/X
because doing so would permit a VERY interesting and useful comparison.
the comparison is interesting because Mac OS/X is tuned very differently
from Linux - even more than the differences it inherits from its *BSD 
heritage.  for instance, if you run LMBench on the two machines, you'll
see that certain syscalls are drastically different in speed.

obviously, Macophiliacs and Apple sales reps would be scandalized
at this idea.  but the truth is that the Xserve hardware is reasonably
competive with dual-xeon alternatives, but in a cluster, no one really
cares about PDF imaging models or other traditional Apple qualities.
what matters is things like TCP stack efficiency, syscall overheads, etc.

> even a G4 one, but I haven't seen anything about G5, is there a linux
> distribution that runs well on this type of machines? or do I better use

I've heard of yellowdog linux; there are probably many other flavors
(perhaps even a fedora version?).  ultimately, the distro is almost 
irrelevant to a cluster, since it's the kernel, booting and FS that 
matter, not .999 of userspace.

incidentally, I've measured the power consumption of a ppc970fx (90nm, 2.0
GHz) system, under load, and found it to be marginally cooler than, say
a similar-speed HP DL145 (dual-opteron).  we're talking 200 vs 220W.
this is old news; what's new is that up-coming 90nm Opterons appear to 
change the picture fairly dramatically, since the drop the TDP from 
89 to 65W.  and of course, for those of you who are cache-friendly,
dual-core opterons at 95W TDP is rather attractive.  (ie, dual ppc970/2.0's 
with a 3.2 GB/s apiece vs four DC opteron/2.2's with 3.2 GB/s apiece.
100W/p vs maybe 60W/p, hmmm.)

regards, mark hahn.

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