Re: [Discuss-gnuradio] GNU Radio multicore support

[Eric Blossom]

On Fri, Sep 14, 2007 at 01:32:33PM -0700, Dan Halperin wrote:
> Hi,
> 
> Old documentation on GNU radio says that it would have transparent
> SMP/multicore/SMT support for signal processing by version 2.x; on 20
> March 2007 Marcus Leech sent an email claiming
> 
> """
> Eventually, Gnu Radio will support multi-threading for processing blocks
> that are particularly expensive, I think, which will be much more useful
> on multi-core CPUs.  Currently I think only the signal processing and
> Gui chains are in different threads.
> """
> 
> Is this still true (I certainly don't see SMP use on my two multicore
> machines), and if so what has prevented this from happening?

FWIW, currently disjoint subgraphs are each run in their own thread.

As part of the work I'm doing for the Cell processor, we'll have a
"thread-per-block" scheduler that will take advantage of SMP/SMT
resources.  We may end up implementing some kind of "work stealing"
technique (c.f. Cilk), where we really run N on M, where M is
f(actual-hw-resources).  A naive "thread-per-block" scheduler
implemented for mblocks has so far turned out to be too heavy-weight
for production use.  The situation may be different with gr_blocks,
since they may burn more cycles (on avg) in their work methods than
the mblocks do.

Eric