Example Usage; Graphical Interface - Red Hat ENTERPRISE LINUX 5 - DEPLOYMENT Deployment Manual

Chapter 39. OProfile
• kernel — If 0, samples are not collected for this counter event when the processor is in kernel-
space; if 1, samples are collected even if the processor is in kernel-space.
• unit_mask — Defines which unit masks are enabled for the counter.
• user — If 0, samples are not collected for the counter event when the processor is in user-space; if
1, samples are collected even if the processor is in user-space.
The values of these files can be retrieved with the cat command. For example:
cat /dev/oprofile/0/count

39.7. Example Usage

While OProfile can be used by developers to analyze application performance, it can also be used by
system administrators to perform system analysis. For example:
• Determine which applications and services are used the most on a system — opreport can be
used to determine how much processor time an application or service uses. If the system is used for
multiple services but is under performing, the services consuming the most processor time can be
moved to dedicated systems.
• Determine processor usage — The CPU_CLK_UNHALTED event can be monitored to determine the
processor load over a given period of time. This data can then be used to determine if additional
processors or a faster processor might improve system performance.

39.8. Graphical Interface

Some OProfile preferences can be set with a graphical interface. To start it, execute the
oprof_start command as root at a shell prompt. To use the graphical interface, you will need to
have the oprofile-gui package installed.
After changing any of the options, save them by clicking the Save and quit button. The preferences
are written to /root/.oprofile/daemonrc, and the application exits. Exiting the application does
not stop OProfile from sampling.
On the Setup tab, to set events for the processor counters as discussed in
Events to Monitor", select the counter from the pulldown menu and select the event from the list.
A brief description of the event appears in the text box below the list. Only events available for the
specific counter and the specific architecture are displayed. The interface also displays whether the
profiler is running and some brief statistics about it.
546
Section 39.2.2, "Setting