# Re: uhd\_rx\_cfile: getting constant O-overflows using the USRP B200 with debian **URL:** \ **Category:** GNU Radio\ **Created:** [March 20, 2014, 11:25am UTC](https://www.ruby-forum.com/t/re-uhd-rx-cfile-getting-constant-o-overflows-using-the-usrp-b200-with-debian/239926 "2014-03-20T11:25:14Z")\ **Posts on this page:** 2\ **Page:** 1
**Author:** ![Detlef\_R](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/58f4c7/32.png) [@Detlef\_R](https://www.ruby-forum.com/u/Detlef_R)\ **Post date:** [March 20, 2014, 11:25am UTC](https://www.ruby-forum.com/t/re-uhd-rx-cfile-getting-constant-o-overflows-using-the-usrp-b200-with-debian/239926/1 "2014-03-20T11:25:14Z")
Hi Aditya, Thanks for your reply. Today I got the chance to measure the lower samplerates and here are the results: I measured the writingspeed on disk and the number of the "O"s for 1 minute runtime. Running X and iotop in the back has nearly no impact. MHz Mb/s “O”-count 32 310 350 16 180 107 8 106 32 4 53 6 2 27 3 Do you have a hint for me for fixing this problem? regards, Ingmar Von: Aditya D. [[mailto:removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)] Gesendet: Mittwoch, 19. Mrz 2014 16:09 An: Ingmar Splitt Cc: removed\_email\_address@domain.invalid Betreff: Re: [Discuss-gnuradio] uhd\_rx\_cfile: getting constant O-overflows using the USRP B200 with debian Hello Ingmar, Can you please repeat the experiment with lower sampling rates (say, 10 Mhz)? Thanks. best, aditya On Wed, Mar 19, 2014 at 8:42 AM, Ingmar Splitt \ wrote: Hi developers, I have a fresh gnu radio installed with pybombs for my usrp B200. It runs on a Lenovo X230 with debian testing x64. When I use uhd\_rx\_cfile i get constant “O”-overruns (output given below). The uhd-benchmark runs without problems: sudo ./benchmark\_rate --duration 600 --rx\_rate 32000000 So the USB3-Port isn’t the Problem. Storing in ram is also fine: sudo ./uhd\_rx\_cfile -f 2445000000 --samp-rate=30000000 /tmp/test.cfile I use a Samsung Evo 840 1TB (newest firmware) and did the SSD-Optimizations ([SSDOptimization - Debian Wiki](https://wiki.debian.org/SSDOptimization)) while searching for the error. HDPerm-, DD- and copy-benchmarks give 500mb/s for the first seconds, later constant ~400mb/s writing speed. Debugging with “iotop” brings (output below) 90% io-call-workload for the benchmarks, but 0% for the uhd\_rx\_cfile which writes only with 240mb/s. So everything should work as expected. Btw: I also get overruns (at a lower rate) when sampling with lower sample rate and try to change the nice number. Have you got any idea how to find and fix the bottleneck? ################################################## user@debian:~/tools/grc/target/bin$ sudo ./uhd\_rx\_cfile -f 2445000000 –samp-rate=30000000 /test/test.cfile -v linux; GNU C++ version 4.8.2; Boost\_105400; UHD\_003.007.000-1-ga8caec5f – Operating over USB 3. – Initialize CODEC control… – Initialize Radio control… – Performing register loopback test… pass – Performing CODEC loopback test… pass – Asking for clock rate 32 MHz – Actually got clock rate 32 MHz – Performing timer loopback test… pass UHD Warning: The hardware does not support the requested RX sample rate: Target sample rate: 30.000000 MSps Actual sample rate: 32.000000 MSps Using mid-point gain of 36.5 ( 0.0 - 73.0 ) Motherboard: B200 (E6R04Z7B2) Daughterboard: B200 (RX2, A:A) Rx gain: 36.5 Rx baseband frequency: 2.445G Rx DDC frequency: -596.046m Rx Sample Rate: 32M Receiving samples until Ctrl-C Writing 32-bit complex floats Output filename: /test/test.cfile OOOOOOOOOOOO ######################################### iotop TID PRIO USER DISK READ DISK WRITE SWAPIN IO\> COMMAND 171 be/4 root 3.91 K/s 0.00 B/s 0.00 % 6.63 % [kworker/u16:3] 2656 be/4 root 0.00 B/s 0.00 B/s 0.00 % 0.04 % X :0 -auth /var/run/lightdm~olisten tcp vt7 -novtswitch 3502 be/4 root 0.00 B/s 236.78 M/s 0.00 % 0.00 % python2 ./uhd\_rx\_cfile -f 2~0000000 /test/test.cfile -v ######################################## messung@debian:~/tools/grc/target/bin$ sudo hdparm -tT /dev/sda /dev/sda: Timing cached reads: 17832 MB in 2.00 seconds = 8921.71 MB/sec Timing buffered disk reads: 1526 MB in 3.00 seconds = 508.55 MB/sec ---
**Author:** ![Ingmar\_Splitt](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/i/ed655f/32.png) [@Ingmar\_Splitt](https://www.ruby-forum.com/u/Ingmar_Splitt)\ **Post date:** [March 20, 2014, 2:30pm UTC](https://www.ruby-forum.com/t/re-uhd-rx-cfile-getting-constant-o-overflows-using-the-usrp-b200-with-debian/239926/2 "2014-03-20T14:30:59Z")
Sorry, I do not. On Thu, Mar 20, 2014 at 6:23 AM, Ingmar Splitt \<