Red Hat Enterprise Linux 5 Administration Unleashed

458CHAPTER 22Monitoring and Tuning ApplicationsThe interface will only let you select event combinations that work for the number ofcounters for your processor. If an event is already selected, click it again to unselect it. Asyou select events, the colored circle icon next to the all the events change colors. If theicon is green, the event may be selected in addition to the already selected ones. If the iconis red, the event cannot be selected in conjunction with the already selected ones.Placing the mouse cursor over an event displays a brief description of the event at thebottom of the application window. Also notice that as you select events to monitor, youcan also select the unit masks specific to the events on the right side of the window. Onthe right side, also select whether to profile the kernel and/or the user binaries.On the Configuration tab as shown in Figure 22.2, provide the full path to the vmlinuxfile of the kernel to profile. Other configuration options available in the graphical interfaceinclude the buffer size and whether to separate the profiles per processor.FIGURE 22.2OProfile Graphical ConfigurationAfter finishing the setup and configuration, click the Reset sample files button to makesure all previous sample files are cleared. Then, click Start to start collecting samples withthe OProfile daemon. Clicking Flush is equivalent to the opcontrol --dump command.Data is flushed to the /var/lib/oprofile/samples/current/ directory. Be sure to flushthe data before clicking Stop to stop the daemon and stop the sampling.ValgrindValgrind is set of debugging and profiling tools for detecting memory and threading problemsand profiling programs to determine if their memory management can be improved.For system administrators, Valgrind is useful for analyzing frequently used programs to