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kern_idle.c revision 1.22 
      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 	for (;;) {
     72 		LOCKDEBUG_BARRIER(NULL, 0);
     73 		KASSERT((l->l_flag & LW_IDLE) != 0);
     74 		KASSERT(ci == curcpu());
     75 		KASSERT(l == curlwp);
     76 		KASSERT(CURCPU_IDLE_P());
     77 		KASSERT(l->l_priority == PRI_IDLE);
     78 
     79 		sched_idle();
     80 		if (!sched_curcpu_runnable_p()) {
     81 			if ((spc->spc_flags & SPCF_OFFLINE) == 0) {
     82 				uvm_pageidlezero();
     83 			}
     84 			if (!sched_curcpu_runnable_p()) {
     85 				cpu_idle();
     86 				if (!sched_curcpu_runnable_p() &&
     87 				    !ci->ci_want_resched) {
     88 					continue;
     89 				}
     90 			}
     91 		}
     92 		KASSERT(l->l_mutex == l->l_cpu->ci_schedstate.spc_lwplock);
     93 		lwp_lock(l);
     94 		mi_switch(l);
     95 		KASSERT(curlwp == l);
     96 		KASSERT(l->l_stat == LSONPROC);
     97 	}
     98 }
     99 
    100 int
    101 create_idle_lwp(struct cpu_info *ci)
    102 {
    103 	lwp_t *l;
    104 	int error;
    105 
    106 	KASSERT(ci->ci_data.cpu_idlelwp == NULL);
    107 	error = kthread_create(PRI_IDLE, KTHREAD_MPSAFE | KTHREAD_IDLE,
    108 	    ci, idle_loop, NULL, &l, "idle/%u", ci->ci_index);
    109 	if (error != 0)
    110 		panic("create_idle_lwp: error %d", error);
    111 	lwp_lock(l);
    112 	l->l_flag |= LW_IDLE;
    113 	lwp_unlock(l);
    114 	l->l_cpu = ci;
    115 	ci->ci_data.cpu_idlelwp = l;
    116 
    117 	return error;
    118 }
    119