On Sun, 2016-06-12 at 18:13 +0100, Bryan O'Donoghue wrote: > On Tue, 2016-06-07 at 13:04 +0300, Andy Shevchenko wrote: > > > I'll find some time to look at both a short stream and a long > > stream, > > > based on the branch you've indicated and maybe against the latest > > > stable kernel. > > > > Please, do. I'm planning to resend new version soon (this week or > > lately beginning of the next one). > > So. > > Generally DMA appears to make little-to-no difference here. Yes, because your test shows the speed of the serial data line. What we are trying to measure here? If you would like to measure CPU load it will require threaded application and some load task to see the difference. Another metric which may help is interrupt counters. I'm wondering if perf can help here as well. > One thing I have noticed is that the following never completes and > can't be reset back to mode=0 or mode=3 to restore functionality - > definitely worth looking at if you are spinning another patch. > > ### never completes #### > root@galileo:~# echo 1 > /sys/class/tty/ttyS0/dma_mode > root@galileo:~# stty -F /dev/ttyS0 921600 > root@galileo:~# time cat tester.txt > /dev/ttyS0 > ### never completes #### Thanks for that test, I will try to reproduce on my side. -- Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> Intel Finland Oy -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
