System-Wide Trap Information

Trap data is provided by running the trapstat software for the duration of the run of the application. However, trapstat is invoked to count system wide traps, not just the traps that are due to this process, so it is not possible to distinguish traps generated by the target process from those generated by other processes running on the machine.

SPOT will gather trap data when passed the -X flag. Trap data is only available if the user has root privileges.

The tool traps is also available stand-alone, outside of spot. Type traps -h to get a list of the options, and consult the traps man page for more details.

Figure 3–8 shows that the trap data is reported as a text summary.

Figure 3–8 System-Wide Trap Data Information

The table reports the average number of traps encountered per second. If the gnuplot software is installed, the results will also be reported as a graph of traps over time.

Figure 3–9 Graph Showing the System-Wide Traps Recorded Over Time

In the graph shown in Figure 3–9, the number of TLB traps is reported over the entire run of the test application. As expected, the traps reported by trapstat correspond to the traps reported by the performance counter on the processor.