RT thread seems blocked

Jan Kiszka jan.kiszka at siemens.com
Tue Mar 24 12:53:15 CET 2020

On 24.03.20 12:43, Bradley Valdenebro Peter (DC-AE/ESW52) wrote:
> Hello,
> We run some tests during the weekend and although we have less occurrences we still indeed see them.
> One interesting thing we see besides the 1ms stalling is that sometimes we see over 100us between IRQ and ISR start.
> At this point we do not know how to proceed further. Any help or suggestion is greatly appreciated.

That is usually where you should start to look into tracing. Option A is 
event-level tracing via standard ftrace. Use

trace-cmd record -e "cobalt*" -e sched -e signal

to record such a trace. Ideally instrument the point where the latency 
is off in your application via xnftrace_printf() (will leave a mark in 
that recorded trace). Check via "trace-cmd report" if the schedule 
around that peak is what you would expect.

For digging even deeper, down to function level: 
specifically look into xntrace_user_freeze(), calling that from your 
application when you spot an excessive latency to stop the trace.

If the result is not clear to you, share it to get a community inspection.


Siemens AG, Corporate Technology, CT RDA IOT SES-DE
Corporate Competence Center Embedded Linux

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