5.3.6. The Timeline

In addition to aggregate data, the summary report also shows you graphs that break down the performance of your code by time. The line graphs depict your code’s behavior in terms of instructions, exceptions, and memory accesses. Hovering over an interval in these charts activates a vertical line in the graph and the Top 5 bar charts to the right of timeline.

To pan across the timelines and see intervals outside of the currently visible values move the mouse cursor to the bottom portion of the graph. This highlights the bottom section of the graph and changes your cursor to a hand. Hold your mouse button down and drag left or right to move the timeline forwards and backwards.

In the upper left hand corner of all three of the timeline graphs is a numeric key. This number represents the highest value shown in the graph and varies depending on the upper limit of the data collected during the execution.

You can specify the interval length by using the controls in the upper right hand corner of the Timeline section. Click on the 1000 ms or 100 ms links to toggle between these values.

The first graph in the Timeline section is the Instructions Executed graph, pictured in Figure 5.6:

Figure 5.6. The Instructions Executed timeline graph

The Instructions Executed timeline graph

The instructions bar chart shows you the total number of instructions and breaks them down by their average CPI. Red indicates an average CPI of six cycles or greater, yellow represents an average CPI between three and six, and green means an average CPI of three or less.

The Exceptions line graph is located underneath the Instructions Executed graph and is pictured in Figure 5.7

Figure 5.7. The Exceptions timeline graph

The Exceptions timeline graph

The highest line in the exceptions graph represents the total number of exceptions that occurred during each interval. These are further broken down by type with each type represented by a different color:

The Memory Accesses timeline graph is just below Exceptions and is pictured in Figure 5.8:

Figure 5.8. The Memory Accesses timeline graph

The Memory Accesses timeline graph

The top of the Memory Accesses timeline graph represents the total accesses to external memory, in bytes, triggered by the profiled code during execution. Like the other timeline graphs, it tracks this value per interval. The red area of the graph represents the number of bytes written, while the green area represents bytes read.

Copyright © 2007- 2009 ARM Limited. All rights reserved.ARM DUI 0414D