Debugging Linux Kernel using ftrace Part12 - Finding kernel functions taking > 10ms

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ftrace uses 'tracing_thresh' file and compare the function duration if  greater than the value present in the file, it logs tracing entries in the ring buffer. By default the value is zero, it means ftrace doesn't care this. The value written in 'tracing_thresh' is in microseconds.

So, if you want to find out the kernel functions which are taking more than 10ms , you need to write
echo '10000' > tracing_thresh


Set back zero in tracing_thresh, if you want to trace all the functions.

echo '0' > tracing_thresh

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