[Xenomai] rpi3 - very high negative latency for simple xeno task
Hi, I have a simple demo program, which just create one rt_task (using native API) and inside the task, I just rt_printf "some logs" for 10 times, with 100us interval. Today I checked this program first time on Raspberry Pi 3, Model B. Xenomai: 3.0.6 ARCH = arm32 Kernel: 4.9.80 for rpi3 Here is the output: - native $ sudo ./simple_xeno_task 10 main: creating task name: task0, priority: 99 Task: 0, Iteration: 10, Sleep duration: 100 us Task[0] - Avg Latency: -9.630 us Task[0] - Max Latency: 0.052 us Task[0] - Min Latency: -67.448 us 1 32.552 -67.448 2 75.261 -24.739 3 97.657 -2.343 4 99.479 -0.521 5 99.791 -0.209 6 99.740 -0.260 7 100.052 0.052 8 99.635 -0.365 9 99.740 -0.260 10 99.792 -0.208 ALL FINISHED...!!! --- If you see, the first 2 iterations have very large negative values. What could be the cause of this? As per RTOS, I expect the output to be close to 100us always. When I run the same program on x86_64 machine I get the below output: ./simple_xeno_task 10 main: creating task name: task0, priority: 99 Task: 0, Iteration: 10, Sleep duration: 100 us Task[0] - Avg Latency: -0.680 us Task[0] - Max Latency: 0.043 us Task[0] - Min Latency: -5.868 us 1 94.132 -5.868 2 99.127 -0.873 3 99.955 -0.045 4 100.043 0.043 5 99.990 -0.010 6 99.959 -0.041 7 100.017 0.017 8 99.977 -0.023 9 99.965 -0.035 10 100.039 0.039 ALL FINISHED...!!! So, I wonder what could be the cause of negative latency on Rpi3 with Xenomai. This is the latency output on Rpi3: -- sudo /usr/xenomai/bin/latency == Sampling period: 1000 us == Test mode: periodic user-mode task == All results in microseconds warming up... RTT| 00:00:01 (periodic user-mode task, 1000 us period, priority 99) RTH|lat min|lat avg|lat max|-overrun|---msw|---lat best|--lat worst RTD| 0.625| 1.374| 5.312| 0| 0| 0.625| 5.312 RTD| 0.624| 1.376| 5.468| 0| 0| 0.624| 5.468 RTD| 0.624| 1.373| 5.676| 0| 0| 0.624| 5.676 RTD| 0.623| 1.372| 9.426| 0| 0| 0.623| 9.426 RTD| 0.467| 1.355| 4.582| 0| 0| 0.467| 9.426 RTD| 0.623| 1.384| 9.113| 0| 0| 0.467| 9.426 RTD| 0.622| 1.379| 5.935| 0| 0| 0.467| 9.426 RTD| 0.622| 1.359| 4.581| 0| 0| 0.467| 9.426 RTD| 0.622| 1.372| 7.028| 0| 0| 0.467| 9.426 RTD| 0.621| 1.361| 6.038| 0| 0| 0.467| 9.426 RTD| 0.621| 1.360| 4.267| 0| 0| 0.467| 9.426 RTD| 0.673| 1.364| 10.256| 0| 0| 0.467| 10.256 RTD| 0.672| 1.363| 6.453| 0| 0| 0.467| 10.256 RTD| 0.620| 1.352| 4.161| 0| 0| 0.467| 10.256 RTD| 0.619| 1.373| 7.234| 0| 0| 0.467| 10.256 RTD| 0.619| 1.352| 6.140| 0| 0| 0.467| 10.256 RTD| 0.671| 1.352| 4.733| 0| 0| 0.467| 10.256 RTD| 0.566| 1.363| 5.514| 0| 0| 0.467| 10.256 RTD| 0.618| 1.368| 6.712| 0| 0| 0.467| 10.256 RTD| 0.618| 1.353| 4.420| 0| 0| 0.467| 10.256 RTD| 0.617| 1.368| 6.815| 0| 0| 0.467| 10.256 ^C---|---|---|---||--|- -- Thanks, Pintu ___ Xenomai mailing list Xenomai@xenomai.org https://xenomai.org/mailman/listinfo/xenomai
Re: [Xenomai] rpi3 - very high negative latency for simple xeno task
Dear Greg, Do you have any comment about this? On Wed, Jun 6, 2018 at 11:11 AM Pintu Kumar wrote: > > Hi, > > I have a simple demo program, which just create one rt_task (using > native API) and inside the task, I just rt_printf "some logs" for 10 > times, with 100us interval. > > Today I checked this program first time on Raspberry Pi 3, Model B. > Xenomai: 3.0.6 > ARCH = arm32 > Kernel: 4.9.80 for rpi3 > > Here is the output: > - > native $ sudo ./simple_xeno_task 10 > main: creating task name: task0, priority: 99 > Task: 0, Iteration: 10, Sleep duration: 100 us > > Task[0] - Avg Latency: -9.630 us > Task[0] - Max Latency: 0.052 us > Task[0] - Min Latency: -67.448 us > 1 32.552 -67.448 > 2 75.261 -24.739 > 3 97.657 -2.343 > 4 99.479 -0.521 > 5 99.791 -0.209 > 6 99.740 -0.260 > 7 100.052 0.052 > 8 99.635 -0.365 > 9 99.740 -0.260 > 10 99.792 -0.208 > ALL FINISHED...!!! > --- > > If you see, the first 2 iterations have very large negative values. > What could be the cause of this? > As per RTOS, I expect the output to be close to 100us always. > > > When I run the same program on x86_64 machine I get the below output: > > ./simple_xeno_task 10 > main: creating task name: task0, priority: 99 > Task: 0, Iteration: 10, Sleep duration: 100 us > > Task[0] - Avg Latency: -0.680 us > Task[0] - Max Latency: 0.043 us > Task[0] - Min Latency: -5.868 us > 1 94.132 -5.868 > 2 99.127 -0.873 > 3 99.955 -0.045 > 4 100.043 0.043 > 5 99.990 -0.010 > 6 99.959 -0.041 > 7 100.017 0.017 > 8 99.977 -0.023 > 9 99.965 -0.035 > 10 100.039 0.039 > ALL FINISHED...!!! > > > So, I wonder what could be the cause of negative latency on Rpi3 with Xenomai. > > > This is the latency output on Rpi3: > -- > sudo /usr/xenomai/bin/latency > == Sampling period: 1000 us > == Test mode: periodic user-mode task > == All results in microseconds > warming up... > RTT| 00:00:01 (periodic user-mode task, 1000 us period, priority 99) > RTH|lat min|lat avg|lat max|-overrun|---msw|---lat best|--lat > worst > RTD| 0.625| 1.374| 5.312| 0| 0| 0.625| > 5.312 > RTD| 0.624| 1.376| 5.468| 0| 0| 0.624| > 5.468 > RTD| 0.624| 1.373| 5.676| 0| 0| 0.624| > 5.676 > RTD| 0.623| 1.372| 9.426| 0| 0| 0.623| > 9.426 > RTD| 0.467| 1.355| 4.582| 0| 0| 0.467| > 9.426 > RTD| 0.623| 1.384| 9.113| 0| 0| 0.467| > 9.426 > RTD| 0.622| 1.379| 5.935| 0| 0| 0.467| > 9.426 > RTD| 0.622| 1.359| 4.581| 0| 0| 0.467| > 9.426 > RTD| 0.622| 1.372| 7.028| 0| 0| 0.467| > 9.426 > RTD| 0.621| 1.361| 6.038| 0| 0| 0.467| > 9.426 > RTD| 0.621| 1.360| 4.267| 0| 0| 0.467| > 9.426 > RTD| 0.673| 1.364| 10.256| 0| 0| 0.467| > 10.256 > RTD| 0.672| 1.363| 6.453| 0| 0| 0.467| > 10.256 > RTD| 0.620| 1.352| 4.161| 0| 0| 0.467| > 10.256 > RTD| 0.619| 1.373| 7.234| 0| 0| 0.467| > 10.256 > RTD| 0.619| 1.352| 6.140| 0| 0| 0.467| > 10.256 > RTD| 0.671| 1.352| 4.733| 0| 0| 0.467| > 10.256 > RTD| 0.566| 1.363| 5.514| 0| 0| 0.467| > 10.256 > RTD| 0.618| 1.368| 6.712| 0| 0| 0.467| > 10.256 > RTD| 0.618| 1.353| 4.420| 0| 0| 0.467| > 10.256 > RTD| 0.617| 1.368| 6.815| 0| 0| 0.467| > 10.256 > ^C---|---|---|---||--|- > > -- > > > Thanks, > Pintu ___ Xenomai mailing list Xenomai@xenomai.org https://xenomai.org/mailman/listinfo/xenomai
Re: [Xenomai] rpi3 - very high negative latency for simple xeno task
Hi Pintu, I just started doing some work recently with the RPI3 to see how Xenomai performs, but I haven't made it too far at the moment. How did you tune the system? -Greg On Sun, Jun 17, 2018 at 10:07 AM, Pintu Kumar wrote: > Dear Greg, > > Do you have any comment about this? > On Wed, Jun 6, 2018 at 11:11 AM Pintu Kumar wrote: >> >> Hi, >> >> I have a simple demo program, which just create one rt_task (using >> native API) and inside the task, I just rt_printf "some logs" for 10 >> times, with 100us interval. >> >> Today I checked this program first time on Raspberry Pi 3, Model B. >> Xenomai: 3.0.6 >> ARCH = arm32 >> Kernel: 4.9.80 for rpi3 >> >> Here is the output: >> - >> native $ sudo ./simple_xeno_task 10 >> main: creating task name: task0, priority: 99 >> Task: 0, Iteration: 10, Sleep duration: 100 us >> >> Task[0] - Avg Latency: -9.630 us >> Task[0] - Max Latency: 0.052 us >> Task[0] - Min Latency: -67.448 us >> 1 32.552 -67.448 >> 2 75.261 -24.739 >> 3 97.657 -2.343 >> 4 99.479 -0.521 >> 5 99.791 -0.209 >> 6 99.740 -0.260 >> 7 100.052 0.052 >> 8 99.635 -0.365 >> 9 99.740 -0.260 >> 10 99.792 -0.208 >> ALL FINISHED...!!! >> --- >> >> If you see, the first 2 iterations have very large negative values. >> What could be the cause of this? >> As per RTOS, I expect the output to be close to 100us always. >> >> >> When I run the same program on x86_64 machine I get the below output: >> >> ./simple_xeno_task 10 >> main: creating task name: task0, priority: 99 >> Task: 0, Iteration: 10, Sleep duration: 100 us >> >> Task[0] - Avg Latency: -0.680 us >> Task[0] - Max Latency: 0.043 us >> Task[0] - Min Latency: -5.868 us >> 1 94.132 -5.868 >> 2 99.127 -0.873 >> 3 99.955 -0.045 >> 4 100.043 0.043 >> 5 99.990 -0.010 >> 6 99.959 -0.041 >> 7 100.017 0.017 >> 8 99.977 -0.023 >> 9 99.965 -0.035 >> 10 100.039 0.039 >> ALL FINISHED...!!! >> >> >> So, I wonder what could be the cause of negative latency on Rpi3 with >> Xenomai. >> >> >> This is the latency output on Rpi3: >> -- >> sudo /usr/xenomai/bin/latency >> == Sampling period: 1000 us >> == Test mode: periodic user-mode task >> == All results in microseconds >> warming up... >> RTT| 00:00:01 (periodic user-mode task, 1000 us period, priority 99) >> RTH|lat min|lat avg|lat max|-overrun|---msw|---lat best|--lat >> worst >> RTD| 0.625| 1.374| 5.312| 0| 0| 0.625| >> 5.312 >> RTD| 0.624| 1.376| 5.468| 0| 0| 0.624| >> 5.468 >> RTD| 0.624| 1.373| 5.676| 0| 0| 0.624| >> 5.676 >> RTD| 0.623| 1.372| 9.426| 0| 0| 0.623| >> 9.426 >> RTD| 0.467| 1.355| 4.582| 0| 0| 0.467| >> 9.426 >> RTD| 0.623| 1.384| 9.113| 0| 0| 0.467| >> 9.426 >> RTD| 0.622| 1.379| 5.935| 0| 0| 0.467| >> 9.426 >> RTD| 0.622| 1.359| 4.581| 0| 0| 0.467| >> 9.426 >> RTD| 0.622| 1.372| 7.028| 0| 0| 0.467| >> 9.426 >> RTD| 0.621| 1.361| 6.038| 0| 0| 0.467| >> 9.426 >> RTD| 0.621| 1.360| 4.267| 0| 0| 0.467| >> 9.426 >> RTD| 0.673| 1.364| 10.256| 0| 0| 0.467| >> 10.256 >> RTD| 0.672| 1.363| 6.453| 0| 0| 0.467| >> 10.256 >> RTD| 0.620| 1.352| 4.161| 0| 0| 0.467| >> 10.256 >> RTD| 0.619| 1.373| 7.234| 0| 0| 0.467| >> 10.256 >> RTD| 0.619| 1.352| 6.140| 0| 0| 0.467| >> 10.256 >> RTD| 0.671| 1.352| 4.733| 0| 0| 0.467| >> 10.256 >> RTD| 0.566| 1.363| 5.514| 0| 0| 0.467| >> 10.256 >> RTD| 0.618| 1.368| 6.712| 0| 0| 0.467| >> 10.256 >> RTD| 0.618| 1.353| 4.420| 0| 0| 0.467| >> 10.256 >> RTD| 0.617| 1.368| 6.815| 0| 0| 0.467| >> 10.256 >> ^C---|---|---|---||--|- >> >> -- >> >> >> Thanks, >> Pintu > > ___ > Xenomai mailing list > Xenomai@xenomai.org > https://xenomai.org/mailman/listinfo/xenomai ___ Xenomai mailing list Xenomai@xenomai.org https://xenomai.org/mailman/listinfo/xenomai
