Re: [Discuss-gnuradio] block buffer sizes

[Eric Blossom]

On Tue, Nov 14, 2006 at 01:24:22PM -0500, address@hidden wrote:
> 
> Hi all,
> 
> is there an easy way to know how big each buffer is in each of the blocks in a
> flow graph, for example:
> 
> src = usrp.sink_c()
> amp = gr.multiply_const_cc(...)
> dst = gr.message_sink_c(...)
> 
> fg.connect(src, amp, dst)
> 
> fg.start()
> 
> #and then check to see how big the buffers were that the scheduler allocated
> buf1 = fg.src.bufferout_size()
> buf2 = fg.amp.bufferout_size() ...
> 
> just curious.
> David Scaperoth

Sorry, there's no way to fetch it from python.

However, the allocate method on line 52 of flow_graph.py is where the
size is determined and the buffer allocated.   You could print it just
before the return.


    def allocate (self, m, index):
        """allocate buffer for output index of block m"""
        item_size = m.output_signature().sizeof_stream_item (index)
        nitems = self.fixed_buffer_size / item_size
        if nitems < 2 * m.output_multiple ():
            nitems = 2 * m.output_multiple ()
            
        # if any downstream blocks is a decimator and/or has a large 
output_multiple, 
        # ensure that we have a buffer at least 2 * their 
decimation_factor*output_multiple
        for mdown in self.flow_graph.downstream_verticies_port(m, index):
            decimation = int(1.0 / mdown.relative_rate())
            nitems = max(nitems, 2 * (decimation * mdown.output_multiple() + 
mdown.history()))

        return buffer (nitems, item_size)        # buffer size in bytes = 
nitems * item_size


Eric