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

[mbaris at metu.edu.tr]

Hi Paul,

Some pointers about the PS3:
instead of yellow dog, opensuse 10.3ppc seems to be better implemented 
(at least I am more used to it), and has a set of cell development 
tools coming right out of the package. yes the amount of ram is a big 
problem, I have tried implementing a swap on a very fast flash memory 
card, at least to lighten the problem, but once you format the card, 
the performance drops significantly. I will be playing with it as soon 
as I have time. Since this is a console, it is -very- hard to tinker 
with the ram, it is a bga chip soldered directly on the second level of 
mainboard pcb, you need a wave soldering technique to remove&replace 
it. In fact, there is a doable method if you are feeling lucky, by 
using a heat gun you can remove the chip, and solder back again with 
applying flux & solder to the pads beforehand, assuming you are -very- 
good with the heat gun and do not fry the chips right away, there are 
still three  problems:
1)since this is a console, the communication between the cpu and the 
ram will most probably be carried on a trusted platform, to prevent 
copied games from running, thus changing the chip will tend to brick 
the system even if you are good with soldering.
2) where do you plan to buy the xddr3 chip? Vandalize from a graphics 
card perhaps? But then again you need to find the exact amount PS3 
uses...
3) How do you plan the architecture to recognize the ram you have installed?
XDDR3 is a multi chip platform, and most probably you should replace 
also the controller.

as with the programming, you should be aware that cell programming is 
not equal to usual parallel programming, in fact the idea is in some 
sense reversed, in the cell, the inter-communication is cheap but the 
ram available to each node is very low (256 kB) and the processors 
themselves are rather low performance. So you should divide your 
program to small&and easy blocks as much as possible, otherwise you get 
a terrible performance.

I nowadays plan to experiment with the new fftw3.2alpha with cell 
support to see if there is a difference.

well, if you are looking for some alternatives, what about nvidia 
tesla? It is basically a high end fpu& generic development tools added 
to your pc via a pci-x slot. I am very optimistic about this 
technology, looking at the amount of work a gpu can pull of nowadays. 
The FPU is not very good at generic calculations, but luckily FFT is 
one of the strong points. As soon as I have the money&time I will try 
implementing it.

Best,

O. Baris Malcioglu
METU Physics.  PhD. Candidate
Ankara