FreeBSD/Linux Kernel Cross Reference
sys/man/thread_set_policy_param.man

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    .\" HISTORY
    .\" $Log:       thread_set_policy_param.man,v $
    .\" Revision 2.2  93/12/07  14:00:14  dbg
    .\"     Created.
    .\" 
    .\" 
    .TH thread_set_policy_param 2 9/22/93
    .CM 4
    .SH NAME
    .nf
    thread_set_policy_param  \-  set scheduling parameters for thread
    thread_set_policy_limit  \-  set max scheduling parameters for thread
    .SH SYNOPSIS
    .nf
    .ft B
    #include <mach.h>
    
    .nf
    .ft B
    kern_return_t thread_set_policy_param(
            thread_t        thread,
            boolean_t       set_limit,
            policy_param_t  param,
            natural_t       param_count);
    
    
    .fi
    .ft P
    .nf
    .ft B
    kern_return_t thread_set_policy_limit(
            thread_t        thread,
            processor_set_t processor_set,
            policy_param_t  limit,
            natural_t       limit_count);
    
    
    .fi
    .ft P
    .SH ARGUMENTS
    .TP 15
    .B
    thread
    The thread whose scheduling parameters are to be changed.
    .TP 15
    .B
    param[param_count]
    The new priority to change it to.
    .TP 15
    .B
    set_limit
    Also set thread's scheduling policy limits if TRUE.
    .TP 15
    .B
    processor_set
    The control port for the processor set to which the 
    thread is currently assigned.
    
    .SH DESCRIPTION
    A thread has two sets of policy parameters associated with it by
    the system: its
    .B current
    policy parameters (for example, the base priority for a timesharing
    thread), and its policy
    .B limit
    parameters (for example, the maximum priority).
    The current policy parameters are used to make scheduling decisions
    about the thread.  For example, the current policy parameter is the
    base priority of a timesharing thread.  The policy parameters may
    be set under user control, but may never exceed the policy limit
    parameters.
    Changing the policy limit requires presentation of the control port
    for the thread's processor set; since the control port for the default
   processor set is privileged, users cannot raise their limits (for example,
   their maximum timesharing priority)
   to unfairly compete with other users on that set.  Newly created threads
   obtain their scheduling policy and parameters from their task,
   and their policy limits from their assigned processor set.
   
   .B thread_set_policy_param
   changes the current policy parameters, and optionally the
   policy limits, of
   .B thread.
   The policy parameters vary depending on the policy; see
   .B thread_set_policy
   for the parameters for each policy.
   The policy limit values of the thread are also set if 
   .B set_limit
   is TRUE.  This call will fail if 
   .B param
   specifies values that exceed the policy limits of the thread.  As
   a result, this call can only lower the policy parameters of
   the thread.
   
   .B thread_set_policy_limit
   changes the policy limit values of the thread.  Because it requires
   presentation of the corresponding processor set port, this call can reset
   the limit to any legal value.
   
   .SH DIAGNOSTICS
   .TP 25
   KERN_SUCCESS
   Operation completed successfully
   .TP 25
   KERN_INVALID_ARGUMENT
   .B thread
   is not a thread, or
   .B processor_set
   is not a control port for a processor set, or
   .B param
   is invalid for the thread's current scheduling policy.
   .TP 25
   KERN_FAILURE
   The requested operation would violate the thread's 
   policy limit values
   (thread_set_policy_param) or the thread is not assigned to the processor set
   whose control port was presented.
   
   .SH BUGS
   Availability limited.
   
   .SH SEE ALSO
   .B thread_set_policy, task_set_default_policy, processor_set_policy_limit
   

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