Nathan Lauener wrote: > > > Jan Kiszka wrote: > >> Nathan Lauener wrote: >> >> >>> Jan Kiszka wrote: >>> >>> >>>> Lauener Nathan wrote: >>>> >>>> >>>> >>>>> Hi, I am using Xenomai to read data from different sensors in real >>>>> time from >>>>> user space. So far I am reading position data from a device >>>>> attached to >>>>> a serial port. The CPU load is at about 1%. I also have a >>>>> microcontroller attached via USB to read encoder data. The USB >>>>> device is >>>>> a USB-to-serial converter. As soon as I open the (USB-)serial port >>>>> with >>>>> normal systemcalls and read the incoming data my CPU load >>>>> skyrockets to >>>>> over 90%. I only read about 30 bytes every 100ms. >>>>> I ran the application on a much newer computer also to rule out any >>>>> buggy hardware. The results stayed the same. Intensively searching the >>>>> mailing list and provided documentation have not helped solve the >>>>> problem. I'm using Xenomai 2.1.0 with kernel 2.6.15.6. Xenomai is >>>>> compiled into >>>>> the kernel. I also use the driver xeno_16550A loaded as module. The >>>>> USB-to-serial bridge used is a CP2101 from Silabs. >>>> Is there any IRQ conflict between the USB host controller and some >>>> RT-device? Please check /proc/interrupts and /proc/xenomai/irq. >>>> >>>> >>>> >>> There is no conflict (interrupt 0 (timer) is the only interrupt >>> mentioned in both listings). >>> >> >> Ok, just to exclude this. >> >> >> >>>> Which process is consuming your CPU time? At system or at user level? >>>> >>>> >>>> >>> It seems that the system consumes the CPU time. Here are the first few >>> lines from opreport >>> >>> CPU: CPU with timer interrupt, speed 0 MHz (estimated) >>> Profiling through timer interrupt >>> samples % image name app name >>> symbol name >>> 1733 31.9742 vmlinux vmlinux >>> default_idle >>> 1151 21.2362 vmlinux vmlinux >>> __ipipe_trace >>> 601 11.0886 libqt-mt.so.3.3.3 libqt-mt.so.3.3.3 (no >>> symbols) >>> 528 9.7417 libc-2.3.2.so libc-2.3.2.so (no >>> symbols) >>> 305 5.6273 vmlinux vmlinux >>> __ipipe_unstall_root >>> 184 3.3948 vmlinux vmlinux >>> __ipipe_dispatch_event >>> 122 2.2509 anon (tgid:4322 range:0x81fb000-0x89b2000) >>> Xorg (no symbols) >>> 100 1.8450 libstdc++.so.5.0.7 libstdc++.so.5.0.7 (no >>> symbols) >>> 97 1.7897 vmlinux vmlinux >>> mcount >>> >>> It looks like the systems gets stuck on the idle task. I do not know >>> what __ipipe_trace exactly does. >>> >> >> __ipipe_trace belongs to the ipipe-tracer you seem to have patched into >> your system. It's called on EVERY kernel function's entry, so it should >> show up on higher ranks. Disable the tracer first to get a more >> consistent profile. >> >> >> >>>> Jan >>>> >>>> >>>> >>>> >>> In my current design I acquire and process the data in the same programm >>> using the Xenomai native skin from user space. This means I link the >>> Xenomai-native and rtdm libraries with several graphics and mathematical >>> libraries. Could this lead to conflicts or problems with Xenomai? >>> >> >> Should not, we do the same here (e.g. with opencv). Anyway, reducing >> your scenario to the minimum that still performs badly can help to >> identify the reason. >> >> > I compiled a reduced version of my programm and also recompiled the > kernel with tracing switched off. Running it 'top' outputs 40% us, 60% > sys, 0% id => 100% CPU load.
Strange. > 'opreport' ouput looks a follows > > CPU: CPU with timer interrupt, speed 0 MHz (estimated) > Profiling through timer interrupt > samples % image name app name > symbol name > 2517 37.4944 vmlinux vmlinux > default_idle Almost 40% idle but still 100% loaded? Did anyone else see top&friends being confused by the presence of Xenomai? I did not so far. > 496 7.3886 libc-2.3.2.so libc-2.3.2.so (no > symbols) > 385 5.7351 vmlinux vmlinux > __ipipe_dispatch_event > 364 5.4223 vmlinux vmlinux > __ipipe_unstall_root > 323 4.8116 vmlinux vmlinux > read_chan > 269 4.0072 libstdc++.so.5.0.7 libstdc++.so.5.0.7 (no > symbols) > 246 3.6645 vmlinux vmlinux > sysenter_past_esp > 155 2.3090 anon (tgid:4245 range:0x81fb000-0x89a4000) > Xorg (no symbols) > 115 1.7131 vmlinux vmlinux > fget_light > 104 1.5492 vmlinux vmlinux > vfs_read > 100 1.4896 libpthread-0.60.so libpthread-0.60.so > __pthread_disable_asynccancel > 98 1.4599 vmlinux vmlinux > add_wait_queue > 97 1.4450 libpthread-0.60.so libpthread-0.60.so > __read_nocancel > 93 1.3854 3Dpos 3Dpos > SerialportReader::run() > 93 1.3854 libpthread-0.60.so libpthread-0.60.so > __pthread_enable_asynccancel > 91 1.3556 vmlinux vmlinux > __ipipe_test_and_stall_root > 87 1.2960 vmlinux vmlinux > tty_ldisc_deref > 85 1.2662 vmlinux vmlinux > remove_wait_queue > 68 1.0130 vmlinux vmlinux > __wake_up > 68 1.0130 vmlinux vmlinux > sys_read > 66 0.9832 vmlinux vmlinux > __ipipe_restore_root > 65 0.9683 vmlinux vmlinux > tty_read > 62 0.9236 vmlinux vmlinux > tty_ldisc_try > 55 0.8193 vmlinux vmlinux > rw_verify_area > 54 0.8044 vmlinux vmlinux > __ipipe_syscall_root > So, on which system service does your application spin then? read(ttyUSBx)? What is the error code of the service that returns probably too often? Maybe some timing assumptions of your usb2serial driver get violated by the presence of the real-time core. Jan
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