[asterisk-dev] OpenCL for improved performance transcoding and conferencing

[Steve Underwood]

  On 09/24/2010 06:02 PM, Chris Coleman wrote:
> Steve, thanks for the input.
>
> You encouraged me to delve deeper.
>
> So, I did, and have some good news.
>
> There is a company in the UK that makes and sells EXACTLY the kind of
> thing I'm talking about.
>
> It is a general purpose GPU, on a PCIe card, with a module for asterisk,
> made to accelerate and offload computation for transcoding and
> conferencing !!
>
> The general-purpose GPU it uses is the IBM CELL processor, same as in
> the Xbox 360 and Playstation 3.
>
> They talk about power savings, and allowing something like 460 channels
> of transcoding, from for example gsm to g.729, without bringing the CPU
> to its knees transcoding the audio, because the GPU is SO MUCH better
> suited to this math work of transcoding.
>
> Here is the source I'm quoting:
>
> http://www.youtube.com/watch?v=0dnFD_vaJ6s
>
> Would like to have the opinion of the group.
>
> Maybe someone feels up to the challenge of implementing some test code....
Howler are out of business, but they didn't make that card. Its 
available from Leadtek. The Windows and Linux SDK is free, and you can 
download it and experiment with the potential of the Cell processor for 
speeding up algorithms. I bought one a few months ago to experiment 
with, and its fairly easy to achieve interesting levels of performance. 
Sadly...

- the Linux SDK is 32 bit only

- a 64 bit Linux SDK will not be made available

- the kernel driver module is supplied as object code, so it can only be 
run with supported kernels (a couple of RHEL/Centos revisions)

- source code is not available for most of the SDK, so 64 bit support 
can't be developed by the user.

So, at the of the day the whole thing looks like a dead end.

The Cell is *nothing* like an nVidia or ATI GPU. It is a far more 
general purpose compute engine. Its much closer to the currently stalled 
Larrabee project at Intel. It is a very good platform for things like 
G.729. A quad core Xeon can easily do more G.729 channels than the Cell 
based chip (actually a Toshiba Spurs Engine chip) on these cards. 
However, the card takes <20W, and working alongside the main quad core 
CPU it is capable of achieving a pretty reasonable balance.

Steve