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kern_idle.c revision 1.10 
      1 /*	$NetBSD: kern_idle.c,v 1.10 2007/12/22 01:14:54 yamt 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 1.10 2007/12/22 01:14:54 yamt 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 
     41 #include <uvm/uvm.h>
     42 #include <uvm/uvm_extern.h>
     43 
     44 void
     45 idle_loop(void *dummy)
     46 {
     47 	struct cpu_info *ci = curcpu();
     48 	struct lwp *l = curlwp;
     49 
     50 	/* Update start time for this thread. */
     51 	lwp_lock(l);
     52 	binuptime(&l->l_stime);
     53 	lwp_unlock(l);
     54 
     55 	KERNEL_UNLOCK_ALL(l, NULL);
     56 	l->l_stat = LSONPROC;
     57 	while (1 /* CONSTCOND */) {
     58 		LOCKDEBUG_BARRIER(NULL, 0);
     59 		KASSERT((l->l_flag & LW_IDLE) != 0);
     60 		KASSERT(ci == curcpu());
     61 		KASSERT(l == curlwp);
     62 		KASSERT(CURCPU_IDLE_P());
     63 		KASSERT(l->l_priority == PRI_IDLE);
     64 
     65 		if (uvm.page_idle_zero) {
     66 			if (sched_curcpu_runnable_p()) {
     67 				goto schedule;
     68 			}
     69 			uvm_pageidlezero();
     70 		}
     71 		if (!sched_curcpu_runnable_p()) {
     72 			cpu_idle();
     73 			if (!sched_curcpu_runnable_p() &&
     74 			    !ci->ci_want_resched) {
     75 				continue;
     76 			}
     77 		}
     78 schedule:
     79 		KASSERT(l->l_mutex == &l->l_cpu->ci_schedstate.spc_lwplock);
     80 		lwp_lock(l);
     81 		mi_switch(l);
     82 		KASSERT(curlwp == l);
     83 		KASSERT(l->l_stat == LSONPROC);
     84 	}
     85 }
     86 
     87 int
     88 create_idle_lwp(struct cpu_info *ci)
     89 {
     90 	lwp_t *l;
     91 	int error;
     92 
     93 	KASSERT(ci->ci_data.cpu_idlelwp == NULL);
     94 	error = kthread_create(PRI_IDLE, KTHREAD_MPSAFE | KTHREAD_IDLE,
     95 	    ci, idle_loop, NULL, &l, "idle/%d", (int)ci->ci_cpuid);
     96 	if (error != 0)
     97 		panic("create_idle_lwp: error %d", error);
     98 	lwp_lock(l);
     99 	l->l_flag |= LW_IDLE;
    100 	lwp_unlock(l);
    101 	l->l_cpu = ci;
    102 	ci->ci_data.cpu_idlelwp = l;
    103 
    104 	return error;
    105 }
    106