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Re: [Discuss-gnuradio] Testing an GRC project runs nearly 200% CPU

From: Marcus Müller
Subject: Re: [Discuss-gnuradio] Testing an GRC project runs nearly 200% CPU
Date: Fri, 16 Jan 2015 09:43:30 +0100
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.3.0

Hi Andreas,

that's kind of interesting, because if it works on a PC, I'd say it's a performance issue; if you don't see aU (audio underruns) or some osmosdr warnings, then I'd say it's not.
What one does in this situation is both running a process-based cpu usage tool; I recommend "htop" (which is like top, but actually a lot nicer). Do you have another process suddenly consume CPU? Does it look like it's pulseaudio (that would be the implicit audio resampling issue)?
If, what I presume, you only see two python processes consuming 100% each, you will need to dig deeper. There's a tool called "perf" [1], which, when run as "perf top" as root will let you introspect CPU usage per method, including kernel routines.
Both perf and htop are available as packets for many Linux distributions.

Best regards,
[1] https://perf.wiki.kernel.org/index.php/Tutorial
On 01/16/2015 09:27 AM, Andreas Ladanyi wrote:
Hi Marcus,
Yes, i tested this project with the same RTL stick on an "old" dual-core (actually i dont  know the exact CPU parameters) notebook and it works perfectly. If i start the project from the console via "python2.7 file.py" i get no warnings.

Hello Andreas,

you never need a throttle block when you have hardware that
limits/defines your real-world sampling rate; in your case, it's your RF
hardware and your sound card.
Aside from things like implicit resampling in the audio card driver
infrastructure, it's absolutely possible that your bananapi is simply
not performant enough to do GUI, signal processing and audio playback at
The question is: Does the same application work sufficiently well on a
fast PC? Do you see any over- or underrun warnings on your console?


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