System Introspection for System Analysis on Mobile Devices

Figure 7.2: Predefined navigation course - The image shows theSLAM map the robot generates by moving around. Therobot starts on point a and navigates to the points b,c,dand e.7.3.4 ResultsFor the different runs the CPU load is analyzed. For each ten runs the measureddata points are aligned and the average <strong>for</strong> corresponding points is calculated.To compare the results the average CPU load of the runs without the probeactive will be referred to as nominal values, while the average values withthe probe active will be referred to as the actual value. Figure 7.3 showsthe average CPU load on both laptops. A first impression is that there isinfluence on the system load by using the probe. Calculating the average andthe standard deviation of this influence (Table 7.4) supports this impression.Looking at the graph does not show a constantly higher usage. To check this allaligned data points where the actual value is higher then the nominal value arecounted. The results reveal that from the 180 aligned data points 146 points(81,11%) on the upper laptop and 161 points (89,44%) on the lower laptophave a higher CPU load. On the lower laptop the average <strong>for</strong> this differenceshows an additional CPU load of 5,86%. On the upper laptop difference showsan additional CPU load of 3,32%. Due to the fact that the evaluation onlypresents a rough estimation one statement here is that there is influence onthe system load. Through the evaluation the laptops never reached a criticallevel where the CPU load was that high no resources could be spared <strong>for</strong> theprobe. If the system reaches a high usage of over 90% the usage of the probe61