FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_idle.c
1 /* $NetBSD: kern_idle.c,v 1.21 2008/06/11 13:42:02 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 1.21 2008/06/11 13:42:02 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 int s;
52
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 spc = &ci->ci_schedstate;
61 s = splsched();
62 spc->spc_flags |= SPCF_RUNNING;
63 splx(s);
64
65 KERNEL_UNLOCK_ALL(l, NULL);
66 l->l_stat = LSONPROC;
67 for (;;) {
68 LOCKDEBUG_BARRIER(NULL, 0);
69 KASSERT((l->l_flag & LW_IDLE) != 0);
70 KASSERT(ci == curcpu());
71 KASSERT(l == curlwp);
72 KASSERT(CURCPU_IDLE_P());
73 KASSERT(l->l_priority == PRI_IDLE);
74
75 sched_idle();
76 if (!sched_curcpu_runnable_p()) {
77 if ((spc->spc_flags & SPCF_OFFLINE) == 0) {
78 uvm_pageidlezero();
79 }
80 if (!sched_curcpu_runnable_p()) {
81 cpu_idle();
82 if (!sched_curcpu_runnable_p() &&
83 !ci->ci_want_resched) {
84 continue;
85 }
86 }
87 }
88 KASSERT(l->l_mutex == l->l_cpu->ci_schedstate.spc_lwplock);
89 lwp_lock(l);
90 mi_switch(l);
91 KASSERT(curlwp == l);
92 KASSERT(l->l_stat == LSONPROC);
93 }
94 }
95
96 int
97 create_idle_lwp(struct cpu_info *ci)
98 {
99 lwp_t *l;
100 int error;
101
102 KASSERT(ci->ci_data.cpu_idlelwp == NULL);
103 error = kthread_create(PRI_IDLE, KTHREAD_MPSAFE | KTHREAD_IDLE,
104 ci, idle_loop, NULL, &l, "idle/%u", ci->ci_index);
105 if (error != 0)
106 panic("create_idle_lwp: error %d", error);
107 lwp_lock(l);
108 l->l_flag |= LW_IDLE;
109 lwp_unlock(l);
110 l->l_cpu = ci;
111 ci->ci_data.cpu_idlelwp = l;
112
113 return error;
114 }
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