[Discuss-gnuradio] what drives noutput_items passed to forecast?

[George Nychis]

Hi all,

I understand the basics that forecast is ensuring the number of input 
items exist to produce a certain number of output items, but what 
exactly drives the number of output items that are passed to forecast()? 
 What drives the scheduler to select this number?

For example, if I run benchmark_rx.py and monitor noutput_items in 
gr_clock_recovery_mm_ff.cc, it looks like this:
http://cyprus.cmcl.cs.cmu.edu/tmp/clockr_forecast

But, what drives this noutput_items parameter decision?

Is the scheduler in an iterative process where, with an exponential 
decay, it asks: "How many input items do i need to produce 
noutput_items?" ... starting at 2^13, which I'm assuming is some sort of 
maximum buffer size?

Then, if it does not have enough items, it decreases the noutput_items 
it is passing exponentially, and asks again... until it has enough input 
items, then calls work().

Thanks!
George