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Use these tools, along with the binaries profiled, to generate reports that can be further analyzed.
Use the `Count` text field to set the sampling rate for the currently selected event as discussed in xref:OProfile.adoc#s3-oprofile-events-sampling[Sampling Rate].
* `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.
Unless OProfile is properly configured, [command]#ophelp# fails with the following error message:
Unit masks for each event are listed with the [command]#ophelp# command. The values for each unit mask are listed in hexadecimal format. To specify more than one unit mask, the hexadecimal values must be combined using a bitwise _or_ operation.
Unit Masks
* `unit_mask` — Defines which unit masks are enabled for the counter.
Understanding the /dev/oprofile/ directory
Unable to open cpu_type file for reading
Make sure you have done opcontrol --init
cpu_type 'unset' is not valid
you should upgrade oprofile or force the use of timer mode
To stop the profiler, execute the following command as root:
To start the monitoring process, for example, on a machine with Westmere processor, run the following command:
To start OProfile from the graphical interface, click btn:[Start]. To stop the profiler, click btn:[Stop]. Exiting the application does not stop OProfile from sampling.
To specify the session directory to hold the sample data, use the [option]`--session-dir` option. If not specified, the data is saved in the `oprofile_data/` directory on the current path.
To set the event for each configurable counter via the command line, use [command]#opcontrol#:
To set the event for each configurable counter via the command line, use:
To save the current set of sample files, execute the following command, replacing _name_ with a unique descriptive name for the current session:
To run [command]#operf# [option]`--system-wide`, you need `root` authority. When finished profiling, you can stop [command]#operf# with `Ctrl+C`.
To resolve this, either boot with the [command]#nmi_watchdog=0# kernel parameter set, or run the following command as `root` to disable `nmi_watchdog` at run time:
To re-enable `nmi_watchdog`, use the following command as `root`:
To profile JIT code from the Java Virtual Machine with the JVMTI agent, add the following to the JVM startup parameters: