Quick guide to ftrace

[Bert Freudenberg]

On 25.11.2009, at 06:52, Chris Ball wrote:
> 
> cjb's quick guide to kernel tracing with ftrace, as used today to
> track down #9702:
> 
> mkdir /debug
> mount -t debugfs debugfs /debug
> cd /debug/tracing
> echo function > current_tracer
> echo "mmc_*" > set_ftrace_filter
> echo "sdhci*" >> set_ftrace_filter
> echo "sdio*" >> set_ftrace_filter
> echo 1 > tracing_on
> echo mem > /sys/power/state
> [resume]
> echo 0 > tracing_on
> cat trace > /root/trace-output


Thanks :)

I'm slightly embarrassed to admit reading the ticket log was highly entertaining to me. Mysterious from the onset, great buildup to the story, a few suspects, powers lost and regained, a crash of the protagonist, some racy bits thrown in, but in the end the innocuously looking C253 is found guilty. Onward to the happy end ...

Great job all, and priceless at the same time!

- Bert -