Re: [Discuss-gnuradio] How to balance workload among cores? Laptop cannot keep up with the USRP2 data flow.

[Eric Blossom]

On Mon, Sep 27, 2010 at 10:07:07AM +0200, Jorge Miguel wrote:
> Hi all!
> 
> I am Tx/Rx a FM signal at the same time, but I can see a lot of SSSSS
> messages that mean my CPU cannot keep up with all frames generated by the
> USRP2 and drop most of them.
> However I have a quite new laptop with a CPU:Intel(R) Core(TM) i5 CPU
> M 520  @ 2.40GHz  on Ubuntu 10.4
> 
> I guess that my laptop is enough to run my FM Tx/Rx and I wonder if I can
> balance the workload among all my four cores to see if my application
> improves (ethernet interface doens't drop any frame).
> 

First off, you don't really have 4 cores.  You've got 2 cores +
hyperthreading (they may have renamed it, but that's what you've got).

GNU Radio will automatically use whatever you've got, without you
having to do anything special.

Be sure that your laptop is in "Performance mode", and not trying to
save energy, or throttle back etc.  There are also some laptops out
there that have poor thermal design and can't really run at full speed
without overheating and thus throttling back the CPU.

Start with something like usrp_fft.py and see how low of a decimation
factor you can work with reliably.  That will give you a basic idea of
how your system is working.

If you're building your own flow graphs, it's quite easy to string
together more blocks, or use a a higher sample rate, than your machine
can keep up with.

After you've ruled out the stuff above, oprofile will help you sort
out which parts of your application are burning the most time.

Eric