-XX:[+|-]RuntimeInstrumentation
(AIX®, Linux®, and z/OS® only)
This option controls the use of the Runtime Instrumentation (RI) facility in the virtual machines that support it.
The RI facility is a feature that is available in POWER8®, zEC12, and later processors that offers hardware support for collecting profiling information at run time. The process uses minimal resources. The use of the RI facility is not enabled by default.
Syntax
-XX:[+|-]RuntimeInstrumentation
| Setting | Effect | Default |
|---|---|---|
-XX:+RuntimeInstrumentation |
Enable | |
-XX:-RuntimeInstrumentation |
Disable | yes |
Note: On Linux, the RI facility on Power 8 and later processors uses the Performance Monitoring Unit (PMU) inside the processor. However, the PMU is also used by system profilers like oprofile or perf. Due to the current Linux kernel implementation, a user cannot reliably profile a Java™ application when RI is enabled. Although this limitation might be addressed in future Linux kernels, for reliable profiling on Power systems that use Linux, the -XX:-RuntimeInstrumentation option must be used.