-XX:[+|-]CpuLoadCompatibility

This option enables or disables the OpenJDK behavior of the getProcessCpuLoad() and getSystemCpuLoad() methods in OpenJ9.

Syntax

    -XX:[+|-]CpuLoadCompatibility

Setting	Effect	Default
-XX:+CpuLoadCompatibility	Enable
-XX:-CpuLoadCompatibility	Disable	yes

Explanation

The getProcessCpuLoad() method in the com.sun.management.OperatingSystemMXBean class returns the recent CPU usage value for the Java virtual machine process, while the getSystemCpuLoad() method returns the recent CPU usage value for the whole system. When these methods were called in OpenJ9 for the first time, these methods were returning -1 to indicate that the recent CPU usage is not available. It was difficult to identify whether the reason for the -1 value was an error or because the call was the first call and therefore, no recent CPU usage was available.

In OpenJDK, these methods return 0 value in the case of the first call, which makes it easier to differentiate between the first call behavior and an error that needs further investigation.

The -XX:+CpuLoadCompatibility option is used to enable the OpenJDK behavior of the getProcessCpuLoad() and getSystemCpuLoad() methods in OpenJ9.