rom/exec/settaskpri.c

   1 /*
   2     Copyright © 1995-2017, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc: Change the priority of a task.
   6     Lang: english
   7 */
   8
   9 #define DEBUG 0
  10 #include <aros/debug.h>
  11
  12 #include <exec/execbase.h>
  13 #include <aros/libcall.h>
  14 #include <proto/exec.h>
  15
  16 #include "exec_intern.h"
  17 #if defined(__AROSEXEC_SMP__)
  18 #include "etask.h"
  19 #include "exec_locks.h"
  20 #endif
  21
  22 /*****************************************************************************
  23
  24     NAME */
  25
  26         AROS_LH2(BYTE, SetTaskPri,
  27
  28 /*  SYNOPSIS */
  29         AROS_LHA(struct Task *, task,      A1),
  30         AROS_LHA(LONG,          priority,  D0),
  31
  32 /*  LOCATION */
  33         struct ExecBase *, SysBase, 50, Exec)
  34
  35 /*  FUNCTION
  36         Change the priority of a given task. As a general rule the higher
  37         the priority the more CPU time a task gets. Useful values are within
  38         -127 to 5.
  39
  40     INPUTS
  41         task     - Pointer to task structure.
  42         priority - New priority of the task.
  43
  44     RESULT
  45         Old task priority.
  46
  47     NOTES
  48
  49     EXAMPLE
  50
  51     BUGS
  52
  53     SEE ALSO
  54
  55     INTERNALS
  56
  57     HISTORY
  58
  59 ******************************************************************************/
  60 {
  61     AROS_LIBFUNC_INIT
  62
  63     struct Task *thisTask = GET_THIS_TASK;
  64 #if defined(__AROSEXEC_SMP__)
  65     spinlock_t *task_listlock = NULL;
  66     int cpunum = KrnGetCPUNumber();
  67 #endif
  68     BYTE old;
  69
  70     D(bug("[Exec] SetTaskPri(0x%p, %d)\n", task, priority);)
  71
  72     /* Always Disable() when doing something with task lists. */
  73 #if defined(__AROSEXEC_SMP__)
  74     switch (task->tc_State)
  75     {
  76         case TS_RUN:
  77             task_listlock =&PrivExecBase(SysBase)->TaskRunningSpinLock;
  78             break;
  79         case TS_WAIT:
  80             task_listlock = &PrivExecBase(SysBase)->TaskWaitSpinLock;
  81             break;
  82         default:
  83             task_listlock = &PrivExecBase(SysBase)->TaskReadySpinLock;
  84             break;
  85     }
  86 #endif
  87     Disable();
  88 #if defined(__AROSEXEC_SMP__)
  89     if (task->tc_State == TS_READY)
  90         EXEC_LOCK_WRITE(task_listlock);
  91     else
  92         EXEC_LOCK_READ(task_listlock);
  93 #endif
  94
  95     /* Get returncode */
  96     old = task->tc_Node.ln_Pri;
  97
  98     /* Set new value. */
  99     task->tc_Node.ln_Pri = priority;
 100
 101     /* Check if the task is willing to run. */
 102     if (task->tc_State != TS_WAIT)
 103     {
 104         /* If it is in the ready list remove and reinsert it. */
 105         if (task->tc_State == TS_READY)
 106         {
 107             Remove(&task->tc_Node);
 108             Enqueue(&SysBase->TaskReady, &task->tc_Node);
 109         }
 110
 111 #if defined(__AROSEXEC_SMP__)
 112         EXEC_UNLOCK(task_listlock);
 113
 114         task_listlock = NULL;
 115         if (IntETask(task->tc_UnionETask.tc_ETask)->iet_CpuNumber == cpunum) {
 116 #endif
 117         if ( task->tc_Node.ln_Pri > thisTask->tc_Node.ln_Pri)
 118         {
 119             D(bug("[Exec] SetTaskPri: Task needs reschedule...\n");)
 120             Reschedule();
 121         }
 122 #if defined(__AROSEXEC_SMP__)
 123         }
 124         else if (task->tc_State == TS_RUN)
 125         {
 126             D(bug("[Exec] SetTaskPri: changing priority of task running on another cpu (%03u)\n", IntETask(task->tc_UnionETask.tc_ETask)->iet_CpuNumber);)
 127             KrnScheduleCPU(IntETask(task->tc_UnionETask.tc_ETask)->iet_CpuAffinity);
 128         }
 129 #endif
 130     }
 131
 132     /* All done. */
 133 #if defined(__AROSEXEC_SMP__)
 134     if (task_listlock)
 135     {
 136         EXEC_UNLOCK(task_listlock);
 137     }
 138 #endif
 139     Enable();
 140
 141     return old;
 142
 143     AROS_LIBFUNC_EXIT
 144 } /* SetTaskPri */