[Pw_forum] Seeking Advice on Small Hardware Platforms for PWscf Implementation

[Paul M. Grant]

To All Forum Members:

I'm planning on building a new Linux box (or boxes) to explore highly
correlated systems (e-p coupling plus LDA+U), and am seeking the collective
experience and advice of the PWscf community on a suitable, inexpensive (<
2000 USD, MB+CPUs+RAM, exclusive of power supplies, enclosures, and
accessories) hardware platform.  I emphasize that the principal purpose of
this new box would be exploratory, or for development, not production.  

I've built several past platforms, both Windows and Linux based, using
server boards manufactured by Supermicro and have had generally good
experience and service (the factory is only 15 miles from where I live).
Currently, I use two machines with dual Xeon processors (single core, 32
bits), one with 1 GHz cpus, 1 GB RAM, the other 2.4 GHz and 3.25 GB RAM,
both with bus speeds of 133 MHz, the newest 3 years old.  However,
occasionally I run PWscf exercises on my little Thinkpad X41 tablet (single
processor, 1.5 GHz, 1.5 GB), and the scf computation will run 3-5 times
faster than on the other machines!  I suspect this rather surprising result
is because the Thinkpad has a 400 MHz bus clock speed.

One option I'm considering is using a "gaming" or server class motherboard
with dual 2.33 GHz quad-core 64-bit processors, a 1333 MHz FSB, and 16 GB
RAM.  Having said this, I'm not sure PWscf (and the Fortran compilers
available) can handle all this parallelism efficiently on a single
motherboard.  I've noticed when running pw.x, the CPU activity "flips"
between processors every several seconds, instead of sharing each at 90-100%
full time.

On the other hand, one could consider building a small MPI-connected cluster
for about the same amount of money.

When IBM announced a couple of years ago the incredible performance details
about the Cell processor that would go into Playstation 3, I thought, "Wow,
maybe the future of computational physics rests with gamers."  I'm sure most
of you know this is actually beginning to happen, spurred on by the fact
that the PS3 is "open architecture" and can run a Linux distro.  Moreover,
there apparently are "open software" numerical analysis tools available from
IBM.  At least four US universities are experimenting with off-the-shelf PS3
clusters, perhaps one of the more interesting is at UMass,
http://gravity.phy.umassd.edu/ps3.html.   In the last week or so, Sony
lowered the entry level price of the PS3 to 400 USD.  So, a cluster of four
with a cheap switch could be purchased for about the same price at the
single motherboard configuration I mentioned above.

My teenager, a gamer, tells me the PS3 has problems.  He says it's
unreliable and overheats and only has 256 MB RAM on board (he owns a Wii,
which outsells the PS3 in the US by a factor of three).

Has anybody tried porting PWscf to a PS3?

Any and all advice is welcome.

Paul M. Grant, PhD
Principal, W2AGZ Technologies
Visiting Scholar, Applied Physics, Stanford University
EPRI Science Fellow (Retired)
IBM Research Staff Member Emeritus
w2agz at pacbell.net
http://www.w2agz.com
 
 


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