Linux Trace Toolkit Reference Manual | |||
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3.1 Probing the kernel
insmod tracer
Having done this, you should see a new entry in /proc/devices.
mknod tracer c [number seen in /proc/devices] 0
I know, I know, this should be automated. I promise I'll do this
one day (I think devfs will end up fixing this for me, I'll transfer to devfs once
it becomes normal practice amongst most distros).
3.2 Probing RTAI
If you've tried to do as prescribed above with an LTT patched RTAI system, then you noticed that you can't install the tracer. The system complains about unresolved symbols. This is because it's a little bit more complicated with RTAI.
insmod [rtai-location]/rtai/modules/rtai_trace
insmod tracer
Having done this, you should see a new entry in /proc/devices.
ADVICE: It is advised that you run the trace daemon at least once as soon as you've
installed the trace driver in order to force it to reserve memory. If you don't do
this, the trace driver might be unable to reserve enough memory to operate. This is a problem
right now because we use __get_free_pages(). Stephen Tweedie strongly suggests using
vmalloc(). I'll try it as soon as I get the time to do so ...
mknod tracer c [number seen in /proc/devices] 0You can now install the other RTAI modules and trace your system.
3.3 Recording the data
A trace begins when the trace daemon starts recording events. If you have followed all the previous steps, this is currently not the case. To start recording, do:
tracedaemon -tsT /dev/tracer ./out.trace ./out.proc
kill [daemon pid]Type ps if you don't know the daemon's PID.
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