Each Java™ priority is mapped to an associated operating system base priority, and each operating system priority is associated with a scheduling policy. The WebSphere® Real Time for AIX® on 64-bit POWER® Linux® operating system scheduling policies are SCHED_OTHER, SCHED_RR and SCHED_FIFO.
Real-time Java threads use policy SCHED_FIFO, while regular Java threads use the policy of the thread that starts the JVM. The default scheduling policy for regular Java threads is SCHED_OTHER, but you can use a utility like chrt to set policies SCHED_RR or SCHED_FIFO. For more information about thread priorities and policies, see Thread scheduling and dispatching.
The following table shows how the Java priorities are mapped to native operating system priorities. Some Java priorities are reserved for use by the JVM, and some native priorities that have no corresponding Java priorities are used by the JVM as well.
Java priorities 1-10: SCHED_OTHER, OS priority 0 Java priority 11: SCHED_FIFO, OS priority 25 Java priority 12: SCHED_FIFO, OS priority 27 Java priority 13: SCHED_FIFO, OS priority 29 Java priority 14: SCHED_FIFO, OS priority 31 Java priority 15: SCHED_FIFO, OS priority 33 Java priority 16: SCHED_FIFO, OS priority 35 Java priority 17: SCHED_FIFO, OS priority 37 Java priority 18: SCHED_FIFO, OS priority 39 Java priority 19: SCHED_FIFO, OS priority 41 Java priority 20: SCHED_FIFO, OS priority 43 Java priority 21: SCHED_FIFO, OS priority 45 Java priority 22: SCHED_FIFO, OS priority 47 Java priority 23: SCHED_FIFO, OS priority 49 Java priority 24: SCHED_FIFO, OS priority 51 Java priority 25: SCHED_FIFO, OS priority 53 Java priority 26: SCHED_FIFO, OS priority 55 Java priority 27: SCHED_FIFO, OS priority 57 Java priority 28: SCHED_FIFO, OS priority 59 Java priority 29: SCHED_FIFO, OS priority 61 Java priority 30: SCHED_FIFO, OS priority 63 Java priority 31: SCHED_FIFO, OS priority 65 Java priority 32: SCHED_FIFO, OS priority 67 Java priority 33: SCHED_FIFO, OS priority 69 Java priority 34: SCHED_FIFO, OS priority 71 Java priority 35: SCHED_FIFO, OS priority 73 Java priority 36: SCHED_FIFO, OS priority 75 Java priority 37: SCHED_FIFO, OS priority 77 Java priority 38: SCHED_FIFO, OS priority 79
Internal Java priority 39: SCHED_FIFO, OS priority 81 Internal Java priority 40: SCHED_FIFO, OS priority 83 Internal Java priority 41: SCHED_FIFO, OS priority 84 Internal Java priority 42: SCHED_FIFO, OS priority 85 Internal Java priority 43: SCHED_FIFO, OS priority 86 Internal Java priority 44: SCHED_FIFO, OS priority 87 Internal Java priority 45: SCHED_FIFO, OS priority 88 OS priorities 11, 12, 13 OS priorities even numbers 26, 28, 30, ..., 82 OS priority 89
See also: the "Synchronization" section in .