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

[Jorge Miguel]

> CPU scheduling is generally the responsibility of the operating system
> kernel, *NOT* Gnu Radio.  What Gnu Radio does is schedule
> blocks to threads, and the execution of those threads, and CPU 
> assignment is up to the kernel.  In general, the kernel does a good
> job of CPU scheduling.

> Your problem is probably that your flow-graphs aren't optimal in some
> way, and thus take more system resources than they should.
Yes, I do not why it takes a lot of resources alhough I can see with gkrellm application that my CPUs are about 50-60%, so it is not so bad.

> The other issue may be your GiGE network interface might be one that
> isn't very good in the buffering department, and thus makes the
>   system work *much* harder than it should handling continuous packet
> traffic.

> What bandwidth are you using?  (That is, what decimation/interpolation
> are you using)?
I am using 30,76Mbps in the transmitter (USRP interpolation sink 104)
I am using  6,25Mbps in the receiver (USRP decimation source 512)

> You haven't shared much in the way of details about your flow-graph, and
> I suspect that's where your problem lies.
I can post my .py file which is:
from gnuradio import audio
from gnuradio import blks2
from gnuradio import gr
from gnuradio import usrp2
from gnuradio.eng_option import eng_option
from gnuradio.gr import firdes

from gnuradio.wxgui import forms
from grc_gnuradio import wxgui as grc_wxgui
from optparse import OptionParser
import wx

class top_block(grc_wxgui.top_block_gui):

	def __init__(self):
		grc_wxgui.top_block_gui.__init__(self, title="Top Block")

		##################################################
		# Variables
		##################################################
		self.tune_osc_dem = tune_osc_dem = 94000000
		self.tune_filter = tune_filter = 75000

		self.samp_rate = samp_rate = 32000
		self.fm_freq_mod = fm_freq_mod = 94000000

		##################################################
		# Controls
		##################################################
		_tune_osc_dem_sizer = wx.BoxSizer(wx.VERTICAL)

		self._tune_osc_dem_text_box = forms.text_box(
			parent=self.GetWin(),
			sizer=_tune_osc_dem_sizer,
			value=self.tune_osc_dem,
			callback=self.set_tune_osc_dem,
			label="Tunned frequency demodulator",

			converter=forms.float_converter(),
			proportion=0,
		)
		self._tune_osc_dem_slider = forms.slider(
			parent=self.GetWin(),
			sizer=_tune_osc_dem_sizer,
			value=self.tune_osc_dem,
			callback=self.set_tune_osc_dem,

			minimum=88000000,
			maximum=108000000,
			num_steps=800,
			style=wx.SL_HORIZONTAL,
			cast=float,
			proportion=1,
		)
		self.Add(_tune_osc_dem_sizer)
		_tune_filter_sizer = wx.BoxSizer(wx.VERTICAL)

		self._tune_filter_text_box = forms.text_box(
			parent=self.GetWin(),
			sizer=_tune_filter_sizer,
			value=self.tune_filter,
			callback=self.set_tune_filter,
			label="LPF Cutoff Freq",
			converter=forms.float_converter(),

			proportion=0,
		)
		self._tune_filter_slider = forms.slider(
			parent=self.GetWin(),
			sizer=_tune_filter_sizer,
			value=self.tune_filter,
			callback=self.set_tune_filter,
			minimum=15000,

			maximum=150000,
			num_steps=1000,
			style=wx.SL_HORIZONTAL,
			cast=float,
			proportion=1,
		)
		self.Add(_tune_filter_sizer)
		_fm_freq_mod_sizer = wx.BoxSizer(wx.VERTICAL)
		self._fm_freq_mod_text_box = forms.text_box(

			parent=self.GetWin(),
			sizer=_fm_freq_mod_sizer,
			value=self.fm_freq_mod,
			callback=self.set_fm_freq_mod,
			label="FM frequency modulator",
			converter=forms.float_converter(),
			proportion=0,

		)
		self._fm_freq_mod_slider = forms.slider(
			parent=self.GetWin(),
			sizer=_fm_freq_mod_sizer,
			value=self.fm_freq_mod,
			callback=self.set_fm_freq_mod,
			minimum=0,
			maximum=110000000,

			num_steps=300,
			style=wx.SL_HORIZONTAL,
			cast=float,
			proportion=1,
		)
		self.Add(_fm_freq_mod_sizer)

		##################################################
		# Blocks
		##################################################

		self.audio_sink_0 = audio.sink(32000, "plughw:0,0", True)
		self.blks2_fm_demod_cf_0 = blks2.fm_demod_cf(
			channel_rate=320000,
			audio_decim=10,
			deviation=75000,
			audio_pass=1000,
			audio_stop=16000,

			gain=20.0,
			tau=75e-6,
		)
		self.blks2_rational_resampler_xxx_0_0 = blks2.rational_resampler_fff(
			interpolation=5,
			decimation=1,
			taps=None,
			fractional_bw=None,
		)
		self.blks2_rational_resampler_xxx_1 = blks2.rational_resampler_fff(

			interpolation=4,
			decimation=1,
			taps=None,
			fractional_bw=None,
		)
		self.blks2_rational_resampler_xxx_1_0_0 = blks2.rational_resampler_ccc(
			interpolation=100,
			decimation=61,
			taps=None,

			fractional_bw=None,
		)
		self.gr_frequency_modulator_fc_0 = gr.frequency_modulator_fc(0.980)
		self.gr_multiply_const_vxx_1 = gr.multiply_const_vcc((32000, ))
		self.gr_wavfile_source_0 = gr.wavfile_source("/home/jorge/Desktop/outfile2.wav", True)

		self.low_pass_filter_0 = gr.fir_filter_ccf(1, firdes.low_pass(
			3, 320000, tune_filter, 5000, firdes.WIN_HAMMING, 6.76))
		self.low_pass_filter_0_0 = gr.interp_fir_filter_fff(1, firdes.low_pass(
			1, 240000, 18e3, 2e3, firdes.WIN_HAMMING, 6.76))

		self.usrp2_sink_xxxx_0 = usrp2.sink_32fc()
		self.usrp2_sink_xxxx_0.set_interp(104)
		self.usrp2_sink_xxxx_0.set_center_freq(fm_freq_mod)
		self.usrp2_sink_xxxx_0.set_gain(0)
		self.usrp2_source_xxxx_0 = usrp2.source_32fc()

		self.usrp2_source_xxxx_0.set_decim(512)
		self.usrp2_source_xxxx_0.set_center_freq(tune_osc_dem)
		self.usrp2_source_xxxx_0.set_gain(10)

		##################################################
		# Connections

		##################################################
		self.connect((self.gr_frequency_modulator_fc_0, 0), (self.gr_multiply_const_vxx_1, 0))
		self.connect((self.blks2_rational_resampler_xxx_0_0, 0), (self.low_pass_filter_0_0, 0))

		self.connect((self.low_pass_filter_0_0, 0), (self.blks2_rational_resampler_xxx_1, 0))
		self.connect((self.gr_wavfile_source_0, 0), (self.blks2_rational_resampler_xxx_0_0, 0))
		self.connect((self.blks2_rational_resampler_xxx_1, 0), (self.gr_frequency_modulator_fc_0, 0))

		self.connect((self.usrp2_source_xxxx_0, 0), (self.blks2_rational_resampler_xxx_1_0_0, 0))
		self.connect((self.blks2_fm_demod_cf_0, 0), (self.audio_sink_0, 0))
		self.connect((self.blks2_rational_resampler_xxx_1_0_0, 0), (self.low_pass_filter_0, 0))

		self.connect((self.low_pass_filter_0, 0), (self.blks2_fm_demod_cf_0, 0))
		self.connect((self.gr_multiply_const_vxx_1, 0), (self.usrp2_sink_xxxx_0, 0))

	def set_tune_osc_dem(self, tune_osc_dem):
		self.tune_osc_dem = tune_osc_dem

		self._tune_osc_dem_slider.set_value(self.tune_osc_dem)
		self._tune_osc_dem_text_box.set_value(self.tune_osc_dem)
		self.usrp2_source_xxxx_0.set_center_freq(self.tune_osc_dem)

	def set_tune_filter(self, tune_filter):

		self.tune_filter = tune_filter
		self.low_pass_filter_0.set_taps(firdes.low_pass(3, 320000, self.tune_filter, 5000, firdes.WIN_HAMMING, 6.76))
		self._tune_filter_slider.set_value(self.tune_filter)
		self._tune_filter_text_box.set_value(self.tune_filter)

	def set_samp_rate(self, samp_rate):
		self.samp_rate = samp_rate

	def set_fm_freq_mod(self, fm_freq_mod):
		self.fm_freq_mod = fm_freq_mod
		self._fm_freq_mod_slider.set_value(self.fm_freq_mod)
		self._fm_freq_mod_text_box.set_value(self.fm_freq_mod)

		self.usrp2_sink_xxxx_0.set_center_freq(self.fm_freq_mod)

if __name__ == '__main__':
	parser = OptionParser(option_class=eng_option, usage="%prog: [options]")
	(options, args) = parser.parse_args()

	tb = top_block()
	tb.Run(True)


Frequency sample rates are matched.
I cannot understand why changing the USRP sink interpolation affects the FM demodulator. 
They should be independent if the Ethernet traffic is under the limit. I see a lot ot SSSSSS mesages and also audio underruns.

Many thanks for your help,
Jorge

> -- 
> Marcus Leech
> Principal Investigator
> Shirleys Bay Radio Astronomy Consortium
> http://www.sbrac.org


> 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).
>
> Looking at other post of the mailing list I found:
>
> 1)"Try using numactl".
> Well, for me is not possible, after installing that library and running:
> :~$ numactl -s
> physcpubind: 0 1 2 3
> No NUMA support available on this system.
>
> 2)"Look at the output of cat /proc/cpuinfo "physical id" indicates
> which cores are in which sockets"
> In all four processors physical id    : 0
>
> Furthermore whe I execute top command I can see:
>  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+     COMMAND 
>  3022 root         20   0  238m  66m  45m   S  166         3.6      
> 3:32.12     python
>
>
> Is my GRC file only executing in one core? How can I find it out?
> Any idea to fix it?
>
> Many thanks,
> Jorge
>
>
>