— Function: kern_return_t thread_policy (thread_t thread, int policy, int data)

The function thread_policy changes the scheduling policy for thread to policy.

data is policy-dependent scheduling information. There are currently two supported policies: POLICY_TIMESHARE and POLICY_FIXEDPRI defined in mach/policy.h; this file is included by mach.h. data is meaningless for timesharing, but is the quantum to be used (in milliseconds) for the fixed priority policy. To be meaningful, this quantum must be a multiple of the basic system quantum (min_quantum) which can be obtained from host_info. The system will always round up to the next multiple of the quantum.

Processor sets may restrict the allowed policies, so this call will fail if the processor set to which thread is currently assigned does not permit policy.

The function returns KERN_SUCCESS if the call succeeded. KERN_INVALID_ARGUMENT if thread is not a thread or policy is not a recognized policy, and KERN_FAILURE if the processor set to which thread is currently assigned does not permit policy.