Re: [Discuss-gnuradio] Non-deterministic behavior in GNU Radio

[Sylvain Munaut]

Hi,

> Unfortunately, there were no further replies to that thread but I did see 
> that my same question "pops up every once in a while". Anyway, my specific 
> problem is I'm trying to QPSK demodulate + RS decode a 2MS/s, 1Mbps bit rate, 
> 10GB IQ file. This works fine, but I'm getting a different number of 
> successfully decoded packets every run. I am using a throttle block, and in 
> fact tried to reduce the throttling rate to 200KHz (samplingrate/10), but it 
> still doesn't seem to work. As for how much CPU my flowgraph is utilizing, it 
> takes up around 80% of all 8 of my CPU cores at the regular sampling rate, 
> while taking around 30% of my cores at samplingrate/10. Do you guys have any 
> idea on what might be going on? The thread I'm referencing is from 2013, but 
> is it still relevant? Any technical reasons for the non-deterministic 
> behavior? I'm using 3.7.13.2.

Depends on your flow graph obviously, but in general, no.

Unless for the obviously "random" blocks (like noise generators and
such), AFAIK most other blocks should have a deterministic behavior
(at least when running on the same exact GR version). Usually
undeterministic behavior points to a bug in one of the blocks that
doesn't properly deal with the boundaries in the work() call.

cheers,

   Sylvain