Re: [Xenomai-help] CPU load over 90%[Scanned]

["Nathan Lauener" <nathan.lauener@domain.hid>]

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.
'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
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
 

>
>Jan
>
>  
>
Nathan