# Getting overflows at 50 Msps (not sure why) **URL:** \ **Category:** GNU Radio\ **Created:** [June 4, 2014, 11:17pm UTC](https://www.ruby-forum.com/t/getting-overflows-at-50-msps-not-sure-why/230214 "2014-06-04T23:17:40Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![jason\_sam](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/7993a0/32.png) [@jason\_sam](https://www.ruby-forum.com/u/jason_sam)\ **Post date:** [June 4, 2014, 11:17pm UTC](https://www.ruby-forum.com/t/getting-overflows-at-50-msps-not-sure-why/230214/1 "2014-06-04T23:17:40Z")
Hello, I am trying to get samples from a B200 at 50 Msps into GNU Radio. The UHD benchmark\_rate tool receives at 50 Msps without any overflows detected. My GNU Radio flowgraph is simply a USRP source connected to a null sink, and I’m still getting overflows. I’ve tried expanding the min\_output\_buffer for the USRP source, but that doesn’t seem to help. I really don’t know what is causing the problem. Any suggestions about what I should try? Thank you, Orin L. ---
**Author:** ![Orin\_L](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/o/90ced4/32.png) [@Orin\_L](https://www.ruby-forum.com/u/Orin_L)\ **Post date:** [June 4, 2014, 11:51pm UTC](https://www.ruby-forum.com/t/getting-overflows-at-50-msps-not-sure-why/230214/2 "2014-06-04T23:51:50Z")
On Wed, Jun 4, 2014 at 5:16 PM, Orin L. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > I am trying to get samples from a B200 at 50 Msps into GNU Radio. The UHD > benchmark\_rate tool receives at 50 Msps without any overflows detected. My > GNU Radio flowgraph is simply a USRP source connected to a null sink, and > I’m still getting overflows. I’ve tried expanding the min\_output\_buffer for > the USRP source, but that doesn’t seem to help. I really don’t know what is > causing the problem. Any suggestions about what I should try? In addition to what Marcus said, if your application allows, you can try 8-bit samples to relieve some pressure on the USB bus. -TT ---
**Author:** ![Orin\_L](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/o/90ced4/32.png) [@Orin\_L](https://www.ruby-forum.com/u/Orin_L)\ **Post date:** [June 4, 2014, 11:22pm UTC](https://www.ruby-forum.com/t/getting-overflows-at-50-msps-not-sure-why/230214/3 "2014-06-04T23:22:58Z")
On 06/04/2014 05:16 PM, Orin L. wrote: > Thank you, > Orin L. > > * * * > > Discuss-gnuradio mailing list > [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) > [Discuss-gnuradio Info Page](https://lists.gnu.org/mailman/listinfo/discuss-gnuradio) What is causing the problem is that your computer/OS simply cannot keep up. Gnu Radio has noticeably more overhead than a hand-crafted program like benchmark\_rate. Being able to maintain real-time streaming at these rates is _challenging_, and just because benchmark\_rate doesn’t fall over, is _zero_ guarantee that some _other_ program, trying to swallow data at a similar rate, will actually be able to. Desktop/Server operating systems (Windows, OSX, Linux, \*BSD) aren’t really optimized for dealing with high-bandwidth real-time flows. In any given system configuration, it’s rather a crap-shoot as to whether your system will be able to keep up or not. What type of computer do you have? What OS? How much memory? Is it the fastest memory you can use on your motherboard? – Marcus L. Principal Investigator Shirleys Bay Radio Astronomy Consortium > **[Live Draw HK Tercepat | Result HK | HK Pools | Live HK | HK Prize Hari Ini](https://www.sbrac.org)** > > Temukan live draw hk tercepat melalui halaman hk pools yang resmi dan dapatkan result hk prize melalui live hk secara langsung di situs kami. ---
**Author:** ![Orin\_L](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/o/90ced4/32.png) [@Orin\_L](https://www.ruby-forum.com/u/Orin_L)\ **Post date:** [June 5, 2014, 12:44am UTC](https://www.ruby-forum.com/t/getting-overflows-at-50-msps-not-sure-why/230214/4 "2014-06-05T00:44:17Z")
On 6/4/2014 2:16 PM, Orin L. wrote: > Thank you, > Orin L. On bladeRF, the number of USB3.0 buffers makes a big difference in the maximum sample rate without overruns. On the B200, you can try the same thing by increasing the number of buffers in the device\_addr arguments. device\_addr=“recv\_frame\_size=65536,num\_recv\_frames=128,…” Ron ---
**Author:** ![Orin\_L](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/o/90ced4/32.png) [@Orin\_L](https://www.ruby-forum.com/u/Orin_L)\ **Post date:** [June 16, 2014, 8:28pm UTC](https://www.ruby-forum.com/t/getting-overflows-at-50-msps-not-sure-why/230214/5 "2014-06-16T20:28:10Z")
I appreciate the suggestions I received. It turns out that I was able to run GNU Radio with realtime priority, and that solved my overflow issues. I am now able to run flowgraphs that actually do things without getting overflows all the time. Thanks, Orin L. ---
**Author:** ![Orin\_L](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/o/90ced4/32.png) [@Orin\_L](https://www.ruby-forum.com/u/Orin_L)\ **Post date:** [June 16, 2014, 10:24pm UTC](https://www.ruby-forum.com/t/getting-overflows-at-50-msps-not-sure-why/230214/6 "2014-06-16T22:24:24Z")
Orin, Just curious what USB 3.0 chipset and OS you are using, and if you can go over 50 Msps? I am able to get 45 Msps UHD Benchmark with the VLI VL80x, but not over that. Thanks, Lou KD4HSO – View this message in context: [http://gnuradio.4.n7.nabble.com/Getting-overflows-at-50-Msps-not-sure-why-tp48774p48945.html](http://gnuradio.4.n7.nabble.com/Getting-overflows-at-50-Msps-not-sure-why-tp48774p48945.html) Sent from the GnuRadio mailing list archive at [Nabble.com](http://Nabble.com). ---
**Author:** ![Orin\_L](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/o/90ced4/32.png) [@Orin\_L](https://www.ruby-forum.com/u/Orin_L)\ **Post date:** [June 16, 2014, 10:30pm UTC](https://www.ruby-forum.com/t/getting-overflows-at-50-msps-not-sure-why/230214/7 "2014-06-16T22:30:20Z")
On 06/16/2014 04:23 PM, madengr wrote: > Orin, > > Just curious what USB 3.0 chipset and OS you are using, and if you can go > over 50 Msps? I am able to get 45 Msps UHD Benchmark with the VLI VL80x, > but not over that. > > Thanks, > Lou > KD4HSO Also, I should point out that getting some high sample-rate in the _benchmark_ application is only a very-vague indicator of how well things will do when you’re actually _doing things_ with the samples. It’s very much cheaper to read samples and throw them away than it is to actually do things, including recording, with said samples. – Marcus L. Principal Investigator Shirleys Bay Radio Astronomy Consortium > **[Live Draw HK Tercepat | Result HK | HK Pools | Live HK | HK Prize Hari Ini](https://www.sbrac.org)** > > Temukan live draw hk tercepat melalui halaman hk pools yang resmi dan dapatkan result hk prize melalui live hk secara langsung di situs kami.