Re: [EXT] Re: Ask for help about cpufreq issue

[Viresh Kumar <viresh.kumar@linaro.org>]

On 14-02-20, 10:00, Andy Tang wrote:
> From cs_dbs_update() function, I did see that sometimes the LOAD is at 100% usage.
> There is almost no application running. That must be some spikes of working running.
> Unfortunately I can't track them by cs_dbs_update() or ftrace tool.
> I doubt the ftrace can be used this way. Do you have any other suggestions? Maybe another tools?

Not sure if you used ftrace correctly, do following steps:

Enable following options in kernel config and rebuild your image.
- CONFIG_FTRACE
- CONFIG_FUNCTION_TRACER

and then run this script at runtime.


-------------------------8<-------------------------
#!/bin/bash
# Locals
BUFFER=40000
FILE="dft"

# What to trace ??
#EVENTS=" -e sched -e power -e workqueue -e irq"
EVENTS="all"

echo "Starting trace"

/usr/bin/trace-cmd start -b $BUFFER $EVENTS

#You can run some test here that you want to trace.
sleep 5

/usr/bin/trace-cmd stop

cat /sys/kernel/debug/tracing/trace > $FILE.txt
/usr/bin/trace-cmd extract -o $FILE.dat

echo "Saved trace in: "$FILE
sync
-------------------------8<-------------------------

The output file here (dft.dat) can be opened with kernel-shark tool.

Your testing platform's userspace must have trace-cmd command for this to work.

-- 
viresh