[USRP-users] UHD 3.10.2 | X300 - High CPU load even for low samples rate

Marcus D. Leech mleech at ripnet.com
Thu Oct 19 17:05:37 EDT 2017


On 10/19/2017 10:25 AM, Kai-Uwe Storek via USRP-users wrote:
> Hey,
>
> after experiencing some problems (time outs, etc) with the current UHD
> develop version (master branch) I changed the UHD version to 3.10.2
> (maint branch, #122bfae).
>
> To do so, I just used the prefix recipe gnuradio-stable via pybombs.
>
> Now I'm not able to transmit even low bandwidth signals. My setup is
>
> - X300 via 1G ethernet
> - gnuradio (maint branch)
> - Debian with kernel 4.9.
>
> I used a simple flow graph with just a sine source directly connected
> to the USRP sink block. Even for sample rates below 2MSamples/s one of
> the cpu core of my Xeon E5-2630 v2 is 100% busy.
>
> Observing the cpu load with htop, I recognized that most of the cpu
> load is red which indicates kernel space activities...
>
> After several seconds I finally got many "U"s in the console window.
>
> Some ideas how to isolate the problem?
> Thanks in advance!
>
> Kai
>
> _______________________________________________
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> USRP-users at lists.ettus.com
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I just constructed the attached flow-graph, and ran it on my ancient 
Dell Latitude laptop:

[mleech at lab ~]$ ./x300_test.py
linux; GNU C++ version 4.8.3 20140911 (Red Hat 4.8.3-7); Boost_105400; 
UHD_003.010.002.000-3-g122bfae1

-- X300 initialization sequence...
-- Determining maximum frame size... 4320 bytes.
-- Setup basic communication...
-- Loading values from EEPROM...
-- Setup RF frontend clocking...
-- Radio 1x clock:200
-- Detecting internal GPSDO.... Found an internal GPSDO: LC_XO, Firmware 
Rev 0.929a
-- [DMA FIFO] Running BIST for FIFO 0... pass (Throughput: 1290.6MB/s)
-- [DMA FIFO] Running BIST for FIFO 1... pass (Throughput: 1309.7MB/s)
-- [RFNoC Radio] Performing register loopback test... pass
-- [RFNoC Radio] Performing register loopback test... pass
-- [RFNoC Radio] Performing register loopback test... pass
-- [RFNoC Radio] Performing register loopback test... pass
-- Performing timer loopback test... pass
-- Performing timer loopback test... pass


No underruns at all, and CPU was quite modest.


Are you running within a VM?



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