On Tue, Nov 22, 2011 at 7:53 PM, Josh Blum <[email protected]> wrote:

>
>
> On 11/22/2011 04:20 PM, Jordan Otomo wrote:
> > Hi,
> >
> > I'm having issues using the hier_block2.  When I create a flowgraph
> > consisting of roughly 12 blocks, I don't get any overruns.  However,
> > combining blocks (e.g. source -> hier_block2 -> sink) results in a
> > ton of overruns.  The parameters of the individual blocks that have
> > been combined into the hier_block2 have not changed.  Does the
> > hier_block2 wait for the work function of each of the blocks it
> > encompasses to return before producing outputs/requesting more
> > inputs?  Any thoughts or advice would be greatly appreciated.
> >
>
> Your saying that a flow graph of *identical* topology has *different*
> performance when moving some of the blocks into a hier block?
>
> If thats the case, its hard to believe. The the flow graph is run, its
> essentially flattened. There is no difference to the scheduler or
> buffers whether or not hierarchical blocks were used.
>
> -josh


Yep, what Josh said. If this really is the case, though, it's definitely a
problem. Instead of using USRPs and looking at the overruns as your
benchmark, could you put in a signal source and a gr_head block of some
number of samples (10 to 100 million or so, enough to get a good
measurement) and switch out your sinks for null_sinks. Run the program and
time it between the non-hier block and the hier block version and let us
know what you get.

Thanks,
Tom
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