Deadmeat (deadmeatoa@yahoo.com) on 8/5/05 wrote:
---------------------------
>Wow, my honor to be talking to you, Linus.
>
>Having stated that, I would like to point you to this document.
>
>http://www-128.ibm.com/developerworks/library/pa-cell/
>
>This article is written by the IBM developer who implemted the APU driver as a
>virtual file system on Linux. He clarifies.

[...]

>One APU requires one CPU thread that "kicked" it, one CPU cannot have two or more APU contexts in execution. Unless
>Sony has another CELL OS with different programming model for games(which I doubt) this one CPU thread per one APU
>rule stays.

Come on... SPUFS is just a single example of how SPEs can be abstracted in Linux. It's neither a fundamental limitation of Cell, nor does it have anything to do with game development.

Don't make the mistake of thinking that's the only, or highest-performance, or easiest-to-implement programming model.

The "resources" section of your SPUFS link points to the following Cell slideshow which discusses several other completely different models for programming the engines:

http://www.research.scea.com/research/html/CellGDC05/index.html

Start on slide 24. You may find it enlightening. Your "kicking & blocking" model is a drop in the bucket. The SPEs appear to be very malleable tools, which can be applied as many different ways as there are software problems to solve.

[...edit lots of Cell speculation and handwringing...]

IMHO you're thinking too hard. Think about accelerating the 5% of code that takes 95% of the processing time in applications that are specialized enough to warrant the work.

The explicitly-managed cache can hurt performance if used ignorantly, but when leveraged properly, has the potential to eliminate access latencies completely.

The whole key to Cell-like heterogenous architectures is that applications that go through the pain of being tailored to them will ride on and benefit from a GPU-like rate of performance growth. Enforced, fine-grain software scalability. It's likely why Sony is looking at PS3 as a 10-year platform; Not because they expect it's so powerful that it will still be relevant in 2015, but because it will scale like mad, far faster than conventional, homogenous "jack of all, master of none" architectures.

fpg