Cell processor notes

I am just jotting down these notes as I go along. Some points may be inaccurate – it just reflects my vague understanding at the time of writing the post. 

I have not yet been able to install the cell processor simulator from IBM. We dont have a powerful enough box to spare at the moment. These are my initial impressions about the cell processor and its suitability for our use.

1. There is a central processor with two hardware threads called the PPE (Power Processing Element). It is either exactly the same as a PowerPC or a slight variant of it.

2. There are eight other processors connected by an extremely high speed ring. These are called SPE (Synergistic Processing Elements). They are kind of crippled compared to the PPE – they dont have branch prediction, or caches. They only have a “scratchpad memory” of 256K.

3. Porting software that works with the PPE is easy. We could probably get by with nothing more than a recompile for the PowerPC. This could give us a major boost over running on another custom hardware platform – both cost and performance wise.

4. Using the SPE is a whole another ball game altogether. We have to rip open our software design from the ground up. The main focus would be to have the PPEs do nothing but feed the SPE with “work” and keep em busy at all times. If we could pull this off – the gains promise to be fantastic. We could do a ton of things at wirespeed.

5. The PS3 is an impressive platform to stage this work. The toolkit “MultiCore Plus SDK” from Mercury seems to be well worth a purchase. It seems to cost less than $500 (I have to verify it).

6. There is very little news about Sony’s Cell BE based board product launch at SIGGRAPH 07. I did find one mention about “Taking the Play out of Playstation“. The features I am interested in the 1U board are :

• Power consumption (the PS3 sucks about 400W)
• Memory type (RDRAM?) + architecture
• Hard drive storage and option for Fiber Channel
• Networking – the PS3 has only 1 GigE port
• Option to purchase without the graphics hardware (HDMI, etc)
• Cost + whether they will sponsor evaluation systems (high hopes here)

 

Author: Vivek Rajagopalan

Vivek Rajagopalan is the a lead developer for Trisul Network Analytics. Prior products were Unsniff Network Analyzer and Unbrowse SNMP. Loves working with packets , very high speed networks, and helping track down the bad guys on the internet. View all posts by Vivek Rajagopalan