tests/sdcard/README

This directory contains tools to profile the sdcard performance.

There are 2 parts to the tool:
* A binary that runs on the device, exercises the sdcard and send
  measurment data back to the host (sdcard_perf_test).
* A host python script to plot the data.

Additionally, there is script 'profile_sdcard.sh' that allows you
to check how the sdcard scale with the number of processes.

INSTALLATION
============
Build, install and mount debugfs. In this directory with a properly
configured enviroment:

  mm SDCARD_TESTS=1
  adb remount
  adb push $ANDROID_PRODUCT_OUT/system/bin/sdcard_perf_test /system/bin/sdcard_perf_test
  adb shell mount -t debugfs none /sys/kernel/debug

If you want to graph the results you need gnuplot and numpy:

  sudo apt-get install gnuplot python-numpy python-numeric

You need Gnuplot.py version 1.8 (not the one coming with ubuntu).
Download it from the Gnuplot.py web site.  Extract to a temp
directory, chdir and run:

  sudo python setup.py install


INVOCATION
==========

Run a simple test:

  adb shell sdcard_perf_test --test=write --size=1000 --chunk-size=100 --procnb=1 --iterations=100

This test will write 1000kbyte (1M) files using writes of 100kbytes (so 10 writes per file) using
only 1 process for 100 times (100 files will be written on the sdcard).
The test will not call sync to flush the writes.
At the end of the test, some stats for the 'open' and 'write' system calls are written.

If you want to plot the data, you need to use the --dump option and provide a file:

  adb shell sdcard_perf_test --test=write --size=1000 --chunk-size=100 --procnb=1 --iterations=100 --dump >/tmp/data.txt

PLOTTING
========

To plot the result using the iter number of the x axis:

  plot_sdcard.py -i /tmp/data.txt

To plot the result using time for the x axis:

  plot_sdcard.py -t /tmp/data.txt

To plot the result from the profiler:

    profile_sdcard.sh
    plot_sdcard.py -p