Using CONFIG_FUNCTION_TRACE

Using CONFIG_FUNCTION_TRACE

[Darren Hart]

I was trying to use CONFIG_FUNCTION_TRACE with the example trace-it.c in 
linux/scripts.  On both 2.6.23.9-rt13 and 2.6.24-rc2-rt1 the system 
slower becomes less responsive (measured by typing in ssh and a serial 
console) until after a couple minutes it doesn't respond to anything 
including sysrq, requiring a power cycle.

The trace-it.c program defaults to 10 seconds of tracing, I even tried 
dropping that to 100 us in case it just added so much overhead that 10 
seconds of idle turned into minutes.  But the 100us sleep hung too.

I tested on a 4 way (2x2) opteron.  

I enabled:

CONFIG_EVENT_TRACE
CONFIG_FUNCTION_TRACE

Thanks,

-- 
Darren Hart
IBM Linux Technology Center
Real-Time Linux Team