sys/kern/kern_idle.c

   1 /*      $NetBSD: kern_idle.c,v 1.22 2009/06/28 09:25:05 ad Exp $        */
   2
   3 /*-
   4  * Copyright (c)2002, 2006, 2007 YAMAMOTO Takashi,
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  26  * SUCH DAMAGE.
  27  */
  28
  29 #include <sys/cdefs.h>
  30
  31 __KERNEL_RCSID(0, "$NetBSD: kern_idle.c,v 1.22 2009/06/28 09:25:05 ad Exp $");
  32
  33 #include <sys/param.h>
  34 #include <sys/cpu.h>
  35 #include <sys/idle.h>
  36 #include <sys/kthread.h>
  37 #include <sys/lockdebug.h>
  38 #include <sys/kmem.h>
  39 #include <sys/proc.h>
  40 #include <sys/atomic.h>
  41
  42 #include <uvm/uvm.h>
  43 #include <uvm/uvm_extern.h>
  44
  45 void
  46 idle_loop(void *dummy)
  47 {
  48         struct cpu_info *ci = curcpu();
  49         struct schedstate_percpu *spc;
  50         struct lwp *l = curlwp;
  51
  52         ci->ci_data.cpu_onproc = l;
  53
  54         /* Update start time for this thread. */
  55         lwp_lock(l);
  56         binuptime(&l->l_stime);
  57         lwp_unlock(l);
  58
  59         /*
  60          * Use spl0() here to ensure that we have the correct interrupt
  61          * priority.  This may be the first thread running on the CPU,
  62          * in which case we took a dirtbag route to get here.
  63          */
  64         spc = &ci->ci_schedstate;
  65         (void)splsched();
  66         spc->spc_flags |= SPCF_RUNNING;
  67         spl0();
  68
  69         KERNEL_UNLOCK_ALL(l, NULL);
  70         l->l_stat = LSONPROC;
  71         l->l_pflag |= LP_RUNNING;
  72         for (;;) {
  73                 LOCKDEBUG_BARRIER(NULL, 0);
  74                 KASSERT((l->l_flag & LW_IDLE) != 0);
  75                 KASSERT(ci == curcpu());
  76                 KASSERT(l == curlwp);
  77                 KASSERT(CURCPU_IDLE_P());
  78                 KASSERT(l->l_priority == PRI_IDLE);
  79
  80                 sched_idle();
  81                 if (!sched_curcpu_runnable_p()) {
  82                         if ((spc->spc_flags & SPCF_OFFLINE) == 0) {
  83                                 uvm_pageidlezero();
  84                         }
  85                         if (!sched_curcpu_runnable_p()) {
  86                                 cpu_idle();
  87                                 if (!sched_curcpu_runnable_p() &&
  88                                     !ci->ci_want_resched) {
  89                                         continue;
  90                                 }
  91                         }
  92                 }
  93                 KASSERT(l->l_mutex == l->l_cpu->ci_schedstate.spc_lwplock);
  94                 lwp_lock(l);
  95                 mi_switch(l);
  96                 KASSERT(curlwp == l);
  97                 KASSERT(l->l_stat == LSONPROC);
  98         }
  99 }
 100
 101 int
 102 create_idle_lwp(struct cpu_info *ci)
 103 {
 104         lwp_t *l;
 105         int error;
 106
 107         KASSERT(ci->ci_data.cpu_idlelwp == NULL);
 108         error = kthread_create(PRI_IDLE, KTHREAD_MPSAFE | KTHREAD_IDLE,
 109             ci, idle_loop, NULL, &l, "idle/%u", ci->ci_index);
 110         if (error != 0)
 111                 panic("create_idle_lwp: error %d", error);
 112         lwp_lock(l);
 113         l->l_flag |= LW_IDLE;
 114         lwp_unlock(l);
 115         l->l_cpu = ci;
 116         ci->ci_data.cpu_idlelwp = l;
 117
 118         return error;
 119 }