State of the Cell

Originally posted at http://cs.ucsb.edu/~cgb/stateOfTheCell.html, and thus, looks much better there.

The Cell Broadband Engine Architecture (which we shall refer to as simply the Cell architecture) was designed as a compromise between the general-purpose but slower CPU and the specific-purpose and faster GPU. It is a heterogeneous architecture: it contains processing units that specialize in different tasks. However, critics (and even some fans) of the Cell architecture claim that it is incredibly difficult to produce good, fast code on it. Having spent the last quarter working with the Cell architecture, we agree with this sentiment. But why?

My Favorite Error Message Ever

While running a Poisson Equation Finite Difference approximation algorithm (whew, a mouthful there!) today on Cell, I got the greatest error message ever:

[cgb@cell pfd]$ ./withRapidMind
terminate called after throwing an instance of ‘rapidmind::Exception’
what(): The type ‘double’ is not supported by the Cell backend.
Aborted

What the hell indeed. Much thanks to the RapidMind guys for an awesome function called “what” and not supporting the double type (although I’m sure there’s a long explanation about that I haven’t found yet).

Setting up Linux on the Cell (Part 2)

So…Yellow Dog Linux doesn’t like SDK 2.1 very much. Turns out I must have done something wrong while trying to install it because it only wants to work on Fedora and I fucked up my ability to compile code for the SPEs and PPE while doing so. So I reinstalled Yellow Dog and this time, followed the very simple explanation at the RapidMind website which said just to install the libspe2 rpm and not mess around with anything else. It worked great, but let’s step back a second here.

Setting up Linux on the Cell (Part 1)

So we got a PS3 for research in the lab the other day and we got to set up Linux on it. It’s actually pretty painless, although if you can, get a monitor that supports DVI and supports HDCP so you can get the digital connection. We only have analog in the lab so it looks like crap. Seriously though, it looks like feces and I have to use SSH to get anything done. That being said, here’s how to do it: