3 Runtime

This topic describes important options that control the runtime behavior of the HotSpot.

Runtime Options

The following table lists important equivalent options of the runtime subsystem in Oracle JRockit and HotSpot:

Table 3-1 Runtime Options

Oracle JRockit	HotSpot	Notes
-XX:+UseLazyUnlocking	-XX:+UseBiasedLocking	UseBiasedLocking improves the performance of uncontended synchronization. This option is enabled by default. However, if the application has high contended synchronization, then disable the UseBiasedLocking option to enhance the performance.
-XlargePages	-XX:+UseLargePages	In HotSpot, this option is enabled by default on the Solaris platform. On the Linux platform, this option was disabled from version 7u60 onwards. Use -XX:+UseLargePages to enable the use of large pages on the platforms where it is disabled by default. However, -XX:+UseLargePages doesn’t enable the use of large pages in the MetaSpace. To enable this option, add -XX:+UseLargePagesInMetaspace.
-XX:MaxLargePageSize	-XX:LargePageSizeInBytes=size	Sets the maximum size (in bytes) for large pages used for the Java heap. By default, the size is set to 0, which implies that the JVM chooses the size for large pages automatically.
-XXcompressedRefs	-XX:+UseCompressedOops	Use of Compressed Oops is the default for 64-bit HotSpot processes when -Xmx isn’t specified and the values of -Xmx are less than 32 gigabytes.