1/*	$NetBSD: kern_idle.c,v 1.24 2011/01/17 07:13:31 uebayasi 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 1.24 2011/01/17 07:13:31 uebayasi 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>	/* uvm_pageidlezero */
43#include <uvm/uvm_extern.h>
44
45void
46idle_loop(void *dummy)
47{
48	struct cpu_info *ci = curcpu();
49	struct schedstate_percpu *spc;
50	struct lwp *l = curlwp;
51
52	kcpuset_atomic_set(kcpuset_running, cpu_index(ci));
53	ci->ci_data.cpu_onproc = l;
54
55	/* Update start time for this thread. */
56	lwp_lock(l);
57	binuptime(&l->l_stime);
58	lwp_unlock(l);
59
60	/*
61	 * Use spl0() here to ensure that we have the correct interrupt
62	 * priority.  This may be the first thread running on the CPU,
63	 * in which case we took a dirtbag route to get here.
64	 */
65	spc = &ci->ci_schedstate;
66	(void)splsched();
67	spc->spc_flags |= SPCF_RUNNING;
68	spl0();
69
70	KERNEL_UNLOCK_ALL(l, NULL);
71	l->l_stat = LSONPROC;
72	l->l_pflag |= LP_RUNNING;
73	for (;;) {
74		LOCKDEBUG_BARRIER(NULL, 0);
75		KASSERT((l->l_flag & LW_IDLE) != 0);
76		KASSERT(ci == curcpu());
77		KASSERT(l == curlwp);
78		KASSERT(CURCPU_IDLE_P());
79		KASSERT(l->l_priority == PRI_IDLE);
80
81		sched_idle();
82		if (!sched_curcpu_runnable_p()) {
83			if ((spc->spc_flags & SPCF_OFFLINE) == 0) {
84				uvm_pageidlezero();
85			}
86			if (!sched_curcpu_runnable_p()) {
87				cpu_idle();
88				if (!sched_curcpu_runnable_p() &&
89				    !ci->ci_want_resched) {
90					continue;
91				}
92			}
93		}
94		KASSERT(l->l_mutex == l->l_cpu->ci_schedstate.spc_lwplock);
95		lwp_lock(l);
96		mi_switch(l);
97		KASSERT(curlwp == l);
98		KASSERT(l->l_stat == LSONPROC);
99	}
100}
101
102int
103create_idle_lwp(struct cpu_info *ci)
104{
105	lwp_t *l;
106	int error;
107
108	KASSERT(ci->ci_data.cpu_idlelwp == NULL);
109	error = kthread_create(PRI_IDLE, KTHREAD_MPSAFE | KTHREAD_IDLE,
110	    ci, idle_loop, NULL, &l, "idle/%u", ci->ci_index);
111	if (error != 0)
112		panic("create_idle_lwp: error %d", error);
113	lwp_lock(l);
114	l->l_flag |= LW_IDLE;
115	lwp_unlock(l);
116	l->l_cpu = ci;
117	ci->ci_data.cpu_idlelwp = l;
118
119	return error;
120}
121