System Introspection for System Analysis on Mobile Devices

For this thesis only a rough estimate can be given on the collected data due tothe fact that the robots behavior is never constant. The navigation control ofthe robot does not create the same path <strong>for</strong> every run. Also several controllingprocesses run in parallel which results in different executions <strong>for</strong> same startingconditions. For the evaluation the assumption is made, that every test run isnearly the same and the collected data of the different runs can be aligned. Tomake a statement about the results, the average of the runs with and withoutthe probe is analyzed.7.3.2 PreparationsThe different components of the robot are controlled by two laptops placed inthe backpack. The laptop controlling the cameras and the speech recognitionwill be referred to as upper laptop, the laptop controlling the navigation willbe referred to as lower laptop. To measure the system load the ToBI plat<strong>for</strong>mis running a predefined navigation procedure traveling along a defined course(Figure 7.2). Through the course four points must be reached by the robot.One round through the course takes the robot 45 seconds. The starting positionof the robot is marked to the ground and <strong>for</strong> each test the robot is placed onthat position. Monitored are both laptops controlling the robot. Each laptop issynchronized against a NTP daemon running on the third laptop. To measurethe CPU load a special tool is written. This tool reads the current CPU load inpercent and appends the results to a file on the local file system. To minimizethe influence of this tool it only collects the data with a frequency of 250 ms.For each test a total of 180 data points is written to the logging file.7.3.3 MethodFor this evaluation a total of 20 runs is per<strong>for</strong>med. For each test the robotnavigates to four predefined points. The first ten runs the probe is not active.On the next ten runs the probe is activated and one client is connected.Be<strong>for</strong>e every test starts the robot is placed at the starting position and thesystem clocks on the main laptops get synchronized. When a single test isexecuted, the logging tool is started synchronously on both laptops and thenavigation procedure starts. After 45 seconds each logging tool automaticallystops recording and writes the result file to the file system.60