Hi, Linux network stack use softirqs for TX-RX actions. In PREEMPT_RT kernel, these softirqs run as RT threads at priority 50. Heavy traffic like ~840Mbps on 2-core machine like P2020 will throttle the system. As scheduler picks the tasks as per priority, the application with SCHED_OTHER policy (non-RT task) will never get a chance to run except in "rt_period - rt_runtime " zone specially reserved for non-rt tasks which is very small. One need to tune various scheduling parameters of various threads running on such a system. We have encountered a similar issue while working on one of networking chip while running heavy traffic. The below article will be useful for you for such kind of problems. http://www.techonline.com/electrical-engineers/education-training/tech-papers/4402454/Challenges-in-Using-Linux-for-CPU-intensive-real-time-networking-products Regards Priyanka > -----Original Message----- > From: linux-rt-users-owner@xxxxxxxxxxxxxxx [mailto:linux-rt-users- > owner@xxxxxxxxxxxxxxx] On Behalf Of Heiko Schumann > Sent: Friday, March 15, 2013 4:42 PM > To: linux-rt-users@xxxxxxxxxxxxxxx > Subject: System freeze while sending data via tcp with 3.6.11-rt30 kernel > > Hi, > > i´ve a 3.6.11-rt30 kernel on a QorIQ P2020 Processor. > Everything works fine, but when i start my application, which sends > data via tcp socket with a rate of ~840 Mbits to an another computer, > the QorIQ P2020 freezes within three minutes. > The application is started with SCHED_OTHER scheduling algorithm the > standard priority. The system freeze occurs until i start the > application with the SCHED_FIFO algorithm and a priority higher then > 50. With this option everything runs stable, but this option > isn´t suitable for the later system. > > I tried this with the 3.6.11-rt25 kernel too and it had the same problem. > With a 3.6.11-rt25 kernel and the "Basic RT" as Preemption Model > instead of "RT" option in kernel options the freeze doesn´t occur, > while running the application with SCHED_OTHER and no priority. > > This are the settings of the 3.6.11-rt30 kernel. Maybe are there > errors i don´t see. > > Thanks for any help with this problem > > -- > To unsubscribe from this list: send the line "unsubscribe linux-rt-users" > in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
