[ltt-dev] Tracing user space program on ARM

Mathieu Desnoyers compudj at krystal.dyndns.org
Fri Jun 19 08:55:16 EDT 2009

* Paul Huang (paulh0803 at gmail.com) wrote:
> Hi~
> I use kernel 2.6.27 for my target(ARM cpu based device).
> I can do the kernel trace with the combination: patch-2.6.27-lttng-0.43 +
> ltt-control-0.56-24102008 + lttv-0.11.3-23102008
> Is possible to have user space tracing for  2.6.27 on ARM?
> If yes, what modifications should I make?

One quick and dirty way :

echo "myevent some raw ascii data" > /mnt/debugfs/ltt/write_event

This will generate an event in the kernel data stream. I just hope this
existed in 2.6.27. Make sure the appropriate kernel option is enabled

> One more question, does any one know how to show the cpu is running in user
> space or kernel space in the LTTViewer?
> I saw there is a diagram of LTT can show the information but I can't find it
> on LTTng.

Well, the control flow view shows when each thread are running, and in
which context (user = green, kernel = blue). We also have a resource
view, which shows the CPU activity. I don't know if this last view was
present in the LTTV version you are using though.

> Thanks for your kindly help!

You're welcome !


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Mathieu Desnoyers
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