sys/kern/kern_idle.c

   1 /*-
   2  * Copyright (c) 2000, All rights reserved.  See /usr/src/COPYRIGHT
   3  *
   4  * $FreeBSD$
   5  */
   6
   7 #include "opt_ktrace.h"
   8
   9 #include <sys/param.h>
  10 #include <sys/systm.h>
  11 #include <sys/kernel.h>
  12 #include <sys/ktr.h>
  13 #include <sys/kthread.h>
  14 #include <sys/lock.h>
  15 #include <sys/mutex.h>
  16 #include <sys/pcpu.h>
  17 #include <sys/proc.h>
  18 #include <sys/resourcevar.h>
  19 #include <sys/smp.h>
  20 #include <sys/unistd.h>
  21 #ifdef KTRACE
  22 #include <sys/uio.h>
  23 #include <sys/ktrace.h>
  24 #endif
  25
  26 static void idle_setup(void *dummy);
  27 SYSINIT(idle_setup, SI_SUB_SCHED_IDLE, SI_ORDER_FIRST, idle_setup, NULL)
  28
  29 static void idle_proc(void *dummy);
  30
  31 /*
  32  * Setup per-cpu idle process contexts.  The AP's shouldn't be running or
  33  * accessing their idle processes at this point, so don't bother with
  34  * locking.
  35  */
  36 static void
  37 idle_setup(void *dummy)
  38 {
  39 #ifdef SMP
  40         struct pcpu *pc;
  41 #endif
  42         struct proc *p;
  43         int error;
  44
  45 #ifdef SMP
  46         SLIST_FOREACH(pc, &cpuhead, pc_allcpu) {
  47                 error = kthread_create(idle_proc, NULL, &p,
  48                     RFSTOPPED | RFHIGHPID, "idle: cpu%d", pc->pc_cpuid);
  49                 pc->pc_idlethread = FIRST_THREAD_IN_PROC(p);
  50                 if (pc->pc_curthread == NULL) {
  51                         pc->pc_curthread = pc->pc_idlethread;
  52                         pc->pc_idlethread->td_critnest = 0;
  53                 }
  54 #else
  55                 error = kthread_create(idle_proc, NULL, &p,
  56                     RFSTOPPED | RFHIGHPID, "idle");
  57                 PCPU_SET(idlethread, FIRST_THREAD_IN_PROC(p));
  58 #endif
  59                 if (error)
  60                         panic("idle_setup: kthread_create error %d\n", error);
  61
  62                 p->p_flag |= P_NOLOAD;
  63                 p->p_stat = SRUN;
  64 #ifdef SMP
  65         }
  66 #endif
  67 }
  68
  69 /*
  70  * idle process context
  71  */
  72 static void
  73 idle_proc(void *dummy)
  74 {
  75 #ifdef DIAGNOSTIC
  76         int count;
  77 #endif
  78
  79         for (;;) {
  80                 mtx_assert(&Giant, MA_NOTOWNED);
  81
  82 #ifdef DIAGNOSTIC
  83                 count = 0;
  84
  85                 while (count >= 0 && procrunnable() == 0) {
  86 #else
  87                 while (procrunnable() == 0) {
  88 #endif
  89                 /*
  90                  * This is a good place to put things to be done in
  91                  * the background, including sanity checks.
  92                  */
  93
  94 #ifdef DIAGNOSTIC
  95                         if (count++ < 0)
  96                                 CTR0(KTR_PROC, "idle_proc: timed out waiting"
  97                                     " for a process");
  98 #endif
  99
 100 #ifdef __i386__
 101                         cpu_idle();
 102 #endif
 103                 }
 104
 105                 mtx_lock_spin(&sched_lock);
 106                 curproc->p_stats->p_ru.ru_nvcsw++;
 107                 mi_switch();
 108                 mtx_unlock_spin(&sched_lock);
 109         }
 110 }