Hi Wael, as someone who keeps processing samples during their days, I very much second Neel's recommendation: From a higher-up perspective, you're trying to do high-performance data processing with low latency restrictions.
Using a slower-than-necessary bus is a bad position to start from, and using a low-end computer with an expensive SDR very much is, too. The same goes for a two-year-old OS with an outdated Linux kernel (updating your Ubuntu to 18.04 would actually solve that problem for free). I can't of course guarantee that your latency requirements will be met – but by at least trying what software you've already built on your laptop on a faster computer, you could see whether a more modern CPU and a more modern operating system help bring you forward. I'd recommend this: Get a large current e.g. Ubuntu 18.04 *bootable USB stick*, and set it up to have *persistent storage*. Install UHD on that, and build your software on it, so that you can take that stick and plug it into any PC, boot it, and try whether it runs better, *without installing anything on that machine*. Then, simply talk to colleagues with a better computer, and try it there, or just walk to your computer store and be honest that you don't know whether a faster PC helps you, but you'd like to try something to learn whether or not you should be buying a new PC from them. Best regards, Marcus On Wed, 2018-07-04 at 08:23 -0700, Neel Pandeya via USRP-users wrote: > Those values can be set through the device string on the command line > with the "--args" option. > > You would be better-served by using a more powerful laptop, one that > uses USB 3.0, as your current laptop only supports USB 2.0. > > --Neel Pandeya > > > > On 4 July 2018 at 01:35, Wael Ali <wa2el....@gmail.com> wrote: > > Thanks Neel, > > > > I've already played with the following values: > > > > recv_frame_size > > num_recv_frames > > send_frame_size > > num_send_frames > > > > in the /b200_impl.cpp file , but I still get the same number of > > late packets in latency_test. > > > > On Wed, Jul 4, 2018 at 6:57 AM Neel Pandeya <neel.pand...@ettus.com > > > wrote: > > > This system is an older low-power system. It's an Intel Core i5 > > > i5-2520M at 2.50 GHz, and is about six or seven years old. > > > > > > You should definitely do some of the performance tuning steps, > > > such as setting the R/W socket buffer sizes, and setting the CPU > > > governors to "performance" mode, etc. > > > > > > https://files.ettus.com/manual/page_transport.html#transport_udp_ > > > sockbufs > > > > > > To reduce latency, I would suggest that you upgrade to a newer > > > more-powerful laptop. > > > > > > Also make sure that you are not seeing any underruns or overruns > > > as your run any UHD programs. You should run "benchmark_rate" at > > > the Tx and Rx sampling rates that your application requires to > > > verify whether your system can reliably sustain those rates. The > > > link below has some information about performance errors ("O", > > > "U", "D", "S", "L"). > > > > > > https://files.ettus.com/manual/page_usrp_x3x0_config.html#x3x0cfg > > > _hosthw_troubleshooting > > > > > > --Neel Pandeya > > > > > > > > > > > > > > > On 3 July 2018 at 20:14, Wael Ali <wa2el....@gmail.com> wrote: > > > > Dear Marcus and Neel > > > > I'm really appreciate your reply > > > > I'm using Dell Latitude E6320, USB 2 > > > > the output of "sudu lshw -html" is attached > > > > I didn't have any kind of tunning except of real-time > > > > scheduling of the uhd > > > > > > > > > > > > On Wed, Jul 4, 2018 at 2:28 AM Neel Pandeya <neel.pandeya@ettus > > > > .com> wrote: > > > > > Your latency will be made up of the delay caused by the USB > > > > > bus itself, which you can't do much about, and the processing > > > > > delay in your host computer. > > > > > > > > > > Have you profiled your application? > > > > > > > > > > Have you done any performance tuning on your system (CPU > > > > > governors, R/W socket buffer sizes, etc.) > > > > > > > > > > What kind of hardware do you have? Could you attach the > > > > > output of "sudo lshw -html"? > > > > > > > > > > --Neel Pandeya > > > > > > > > > > > > > > > > > > > > > > > > > On 3 July 2018 at 14:57, Marcus D. Leech via USRP-users <usrp > > > > > -us...@lists.ettus.com> wrote: > > > > > > On 07/03/2018 05:10 PM, Wael Ali via USRP-users wrote: > > > > > > > Dear all, > > > > > > > please help me with this issue, > > > > > > > > > > > > > > while I'm testing latency between uhd and b205mini with > > > > > > > latency_test file provided with uhd examples gives me the > > > > > > > following > > > > > > > > > > > > > > Summary (test1) > > > > > > > ================ > > > > > > > Number of runs: 1000 > > > > > > > RTT value tested: 1 ms > > > > > > > ACKs received: 302/1000 > > > > > > > Underruns: 0 > > > > > > > Late packets: 698 > > > > > > > Other errors: 0 > > > > > > > > > > > > > > Summary (test2) > > > > > > > ================ > > > > > > > Number of runs: 1000 > > > > > > > RTT value tested: 2 ms > > > > > > > ACKs received: 784/1000 > > > > > > > Underruns: 0 > > > > > > > Late packets: 216 > > > > > > > Other errors: 0 > > > > > > > > > > > > > > I need rrt<= 1ms, and I need to know, > > > > > > > how to reduce the latency between uhd and the device? > > > > > > > Is this a hardware issue (related to usb port)? > > > > > > > > > > > > > > I've already tried to use low latency linux kernel, but > > > > > > > the results were almost the same. > > > > > > > > > > > > > > OS: Ubuntu 16.04 > > > > > > > Kernel: 4.13.0-36-generic > > > > > > > UHD: 3.12.0.HEAD-0-gec786351 > > > > > > > libusb: 0.1.12 > > > > > > > > > > > > > > Thanks is advance > > > > > > > Wael Ali > > > > > > > > > > > > > > > > > > > What type of computer? Are you using USB3.0, or USB2.0? > > > > > > > > > > > > > > > > > > > > > > > > _______________________________________________ > > > > > > USRP-users mailing list > > > > > > USRP-users@lists.ettus.com > > > > > > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.et > > > > > > tus.com > > > > > > > > _______________________________________________ > USRP-users mailing list > USRP-users@lists.ettus.com > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com _______________________________________________ USRP-users mailing list USRP-users@lists.ettus.com http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
