Too Busy For Words - the PaulWay Blog

Fri 23rd Feb, 2007

CLUG February meeting - PS3 and Sushi

It's at times like this that I'm really glad I discovered the CLUG.

Firstly, the main focus of the presentation was the PS3. Hugh Blemings and Jeremy Kerr (I think) gave a talk about the heart of the PS3, and several of IBM's large blade servers, the Cell processor. I'll gloss over a lot of the technical detail because it's pretty easy to find, but the key things to me were:

Of course, writing code for the Cell's Secondary Processing Units - the eight 'sub-processors' that do most of the SIMD work - is not an easy process. The 'Hello World' example involved lots of complicated IO, but that was only because the SPU isn't the right platform to use to put words on the console. What Jeremy and Hugh are interested in is seeing various libraries - FFT, audio and video codecs, rendering libraries, all sorts of other things that require lots of brute-force computation - ported to use the Cell's SPUs. The power of these things is not to be underestimated: their classic demo is a four-dimensional jula set (!) made of glass (!) ray-tracing (!!) in real-time (!!!), and it's done with no clever OpenGL output, just blatting pixels onto a frame buffer. With so much work being done on general-purpose data processing algorithms that can be run on the Graphics Processing Unit of your modern graphics card, this offers significant performance increases if we can get these libraries in place.

Nick Piggin also gave a talk about his work on getting better performance from NUMA machines. NUMA is Non Uniform memory Access, where each processor or core has direct access only to a subsection of the total memory in the system, and has to ask for other blocks to be sent to it if the block it wants is attached to another processor. Blocks that are read-only can be duplicated in each processor's local memory: for example, the pages containing libc. Blocks that are read-write can be replicated while everyone's only reading them, and flushed out and reloaded when a write occurs. So overall this was a night for the supercomputing enthusiasts amongst us (e.g. me).

(Note to self: I need to find a good way to talk to Nick about his presentation style.)

Once most of the presenting is over, the night is given over to eating and chatting. Usually in CLUG meetings this is given over to a pizza feeding frenzy once famously compared to a gannet colony. Last night, however, we also had sushi. This was organised by myself with some assistance from Pascal Klein, and had to be arranged in advance. It was an experiment in alternative foods prompted by Hugh Fisher's talk on Open Source software communities. We had seven people, Hugh and Jeremy included, request sushi; one didn't show up, so despite me asking for an eighth person to join in we still only had seven people sharing the cost. So I got stuck with a bit of the bill, but it was worth it for the quantity of sushi. There was a good variety, in reasonably good quality, and enough wasabi to entirely destroy the sinuses of the entire CLUG attendance for the night. So I think this was a success; I'll do it next time.

I'm still casting around for other cuisines that have small, easy to eat portions that don't require cutlery and can be sourced relatively quickly and don't go off their serving temperature for the period they're stored between picking them up and dispensing them. But sushi twice in a row won't be all that bad...

Addendum: I called my brother up in Brisbane to tell him of the PS3 coolness, and ended up spending more time talking to his friend Nick who works there. Nick's a linux user in a crowd of Windows geeks, like myself, so we ended up chewing the fat over processing coolness and Vista badness for a good hour or so. I also passed on to him the news about http://www.debian-multimedia.org - i.e. that it exists. That should save him the agony of getting MythTV to compile...

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