Re: [9fans] Barrelfish

[Sam Watkins <sam@nipl.net>]

On Mon, Oct 19, 2009 at 12:05:19PM -0400, erik quanstrom wrote:
> > Details of the calculation: 7200 seconds * 30fps * 12*16 (50*50 pixel
> > chunks) * 500000 elementary arithmetic/logical operations in a pipeline
> > (unrolled).  7200*30*12*16*500000 = 20 trillion (20,000,000,000,000)
> > processing units.  This is only a very rough estimate and does not consider
> > all the issues.
>
> could you do a similar calcuation for the memory bandwidth required to
> deliver said instructions to the processors?

The "processors" (actually smaller processing units) would mostly be configured
at load time, much like an FPGA.  Most units would execute a single simple
operation repeatedly on streams of data, they would not read instructions and
execute them sequentially like a normal CPU.

The data would travel through the system step by step, it would mostly not need
to be stored in RAM.  If some RAM was needed, it would be small amounts on
chip, at appropriate places in the pipeline.

Some programs (not so much video encoding I think) do need a lot of RAM for
intermediate calculations, or IO for example to fetch stuff from a database.
Such systems can also be designed as networks of simple processing units
connected by data streams / pipelines.

Sam