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Re: [Discuss-gnuradio] Profiling, stopping the flow graph

From: Dan Halperin
Subject: Re: [Discuss-gnuradio] Profiling, stopping the flow graph
Date: Mon, 29 Jan 2007 11:40:54 -0800
User-agent: Thunderbird (X11/20070103)

Eric Blossom wrote:
> On Mon, Jan 29, 2007 at 10:35:33AM -0800, Dan Halperin wrote:
>> Hi,
>> What options are there for profiling GNU Radio code? I've done some
>> Python profiling, and some C profiling, but what options are there for
>> this crazy SWIG-driven mix of the two?
> Oprofile (oprofile.sf.net) kicks ass.  It'll profile anything
> including our Python and C++ and the kernel, without having to add
> instrumentation to the generated code.  It uses the hardware
> performance counters.

Awesome, I'll check it out. Thanks! (At the moment, having trouble
getting it started under Ubuntu..).

>> Also, a flow graph question. In the main loop of the transmit path of my
>> benchmarking program, I have the following (hopefully self-explanatory
>> code):
>>         fg.start()
>>         self.num_to_send = options.packets
>>         self.bytes_per_packet = options.bytes
>>         util.rand_init(options.seed)
>>         for i in range(self.num_to_send):
>>             # generate random payload here into buf
>>             buf = util.random_bytes(self.bytes_per_packet)
>>             if i % 10 == 0:
>>                 print "> sending packet #", i
>>             mac.send_buffer_unreliably(buf)
>> #            sleep(.01)
>> #        sleep (1)
>> #        sys.exit(0)
>>         fg.stop()     # tell flow graph to stop.
>>         fg.wait()     # wait for it to finish
>> If the sleep(.01) line is uncommented, then the flow graph does not
>> stop, and instead I quit using the sleep(1); sys.exit(0); however
>> everything works fine with no sleeping. What could be causing this? Is
>> it something weird involving code running in the same thread that
>> shouldn't be?
>> Thanks,
>> Dan
> Is the receiver code in the same program?  If so, the flow graph code
> won't exit until both indicate they are done.
> Do you understand the use of the eof flag in
> gnuradio-examples/python/usrp/digital/benchmark_tx.py?  
> It ends up sending (in pkt.py (send_pkt)) a special message (type == 1
> vs type == 0) to the gr.message_source that feeds the modulator.  The
> special message tells the source that we're not sending any more data.
> This results in the C++ code telling the scheduler that it's done, and
> ultimately the flow graph stops.

That was the problem; I'm an idiot. I forgot to copy that line from the
original program. Thanks.

> Also, from this fragment I'm not sure if you are invoking the sleep(3)
> function or the time.sleep function.  You definitely want the latter.

The latter.

Thanks for your help,


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