Profiling 0xdroid

This document describes how to do system wise profiling via oprofile in 0xdroid.
Original Android supports oprofile, however it only supports ARMv6.
In beagle-cupcake our target device is beagleboard, in which is powered via omap3530 with ARMv7 arch.
Therefore we did some hack around the external/oprofile and update new prebuild oprofile utils and let the oprofile supports ARMv7.
The prebuild files change nothing but using the same architecture table in external/oprofile.
Therefore you will need to use the prebuild opreport to analysis the logs.

The following is a mini how-to of using it.

Kernel setting

0xdroid kernel does not enable oprofile flag in default. You need to turn it on by your self.
You can reference to Build-from-Scratch and build your own kernel.
To enable OPROFILE flags you will need to turn the following flags on:
+ CONFIG_OPROFILE_ARMV7=y
+ CONFIG_OPROFILE=y
+ CONFIG_PROFILING=y
+ CONFIG_HAVE_OPROFILE=y
+ CONFIG_TRACEPOINTS=y

Run on beagleboard

You can use opcontrol to start and stop profiling on beagleboard. You can also choose logging kernel symbols or not.
If you want to log kernel symbols you need to put the vmlinux into beagleboard, in my case I put that on a usb mass storage.
and mount that on /sdcard


/system/bin/mount -t vfat /dev/block/sda1 /sdcard
setprop EXTERNAL_STORAGE_STATE mounted
am broadcast -a android.intent.action.MEDIA_MOUNTED —ez read-only false -d file:///sdcard

Before starting profiling you will need to setup the oprofile, you can reference to oprofile manual.
Here is how I setup the oprofile:


opcontrol —setup —event=CPU_CYCLES:15000:::1:1 —vmlinux=/sdcard/vmlinux —kernel-range=0xc0008000,0xcfffffff
echo 16 > /dev/oprofile/backtrace_depth
opcontrol —start

Then do activity you want to be profiled.
After finish do the following command to stop profiling.


opcontrol —stop

Analysis

After profiling, you will need to move all the data to host to do analysis. Therefore you can choose use usb ethernet to do such task.

Connecting beagleboard

On device:
1. plug in usb line between laptop and beagleboard (OTG port)
2. netcfg usb0 up
3. ifconfig usb0 192.168.0.202
On laptop:
1. sudo ifconfig usb0 192.168.0.200 # beware nm-applet may breaks it, you can set it up.
2. export ADBHOST=192.168.0.202
3. export PATH={Where you put 0xdroid}/out/host/linux-x86/bin:$PATH
4. pkill adb
5. adb devices # If you can see the device then you can do next step, or you may need to checkout what’s wrong.

opimport_pull

Using the script external/oprofile/opimport_pull to pull down samples and analysis them.


cd {Where you put 0xdroid}
. build/envsetup.sh
setpaths
export OPROFILE_EVENTS_DIR=${PWD}/linux-x86/oprofile/
cd external/oprofile
./opimport_pull /tmp/beagle-cupcake-oprofile

Then the script will pull down samples from beagleboard and do the symbol analysis once for you.
If you want to dig out more information, you can use:


cp ${Where you build your kernel}/vmlinux ${OUT}/symbols
${OPROFILE_EVENTS_DIR}/bin/opreport —session-dir=/tmp/beagle-cupcake-oprofile -p ${OUT}/symbols -d

Enjoy it!

for geeks

You can check the script of opimport_pull and do whatever you want, even add graphvis supports.
You can also move out the /data/oprofile to other SD card and so that you can not using opimport_pull.

Oprofile