FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_idle.c
1 /*-
2 * Copyright (C) 2000-2004 The FreeBSD Project. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY AUTHOR AND CONTRIBUTORS ``AS IS'' AND
14 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
16 * ARE DISCLAIMED. IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS BE LIABLE
17 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
18 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
19 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
20 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
21 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
22 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
23 * SUCH DAMAGE.
24 */
25
26 #include <sys/cdefs.h>
27 __FBSDID("$FreeBSD$");
28
29 #include <sys/param.h>
30 #include <sys/systm.h>
31 #include <sys/kernel.h>
32 #include <sys/kthread.h>
33 #include <sys/lock.h>
34 #include <sys/mutex.h>
35 #include <sys/proc.h>
36 #include <sys/resourcevar.h>
37 #include <sys/sched.h>
38 #include <sys/unistd.h>
39 #ifdef SMP
40 #include <sys/smp.h>
41 #endif
42
43 static void idle_setup(void *dummy);
44 SYSINIT(idle_setup, SI_SUB_SCHED_IDLE, SI_ORDER_FIRST, idle_setup, NULL)
45
46 static void idle_proc(void *dummy);
47
48 /*
49 * Set up per-cpu idle process contexts. The AP's shouldn't be running or
50 * accessing their idle processes at this point, so don't bother with
51 * locking.
52 */
53 static void
54 idle_setup(void *dummy)
55 {
56 #ifdef SMP
57 struct pcpu *pc;
58 #endif
59 struct proc *p;
60 struct thread *td;
61 int error;
62
63 #ifdef SMP
64 SLIST_FOREACH(pc, &cpuhead, pc_allcpu) {
65 error = kthread_create(idle_proc, NULL, &p,
66 RFSTOPPED | RFHIGHPID, 0, "idle: cpu%d", pc->pc_cpuid);
67 pc->pc_idlethread = FIRST_THREAD_IN_PROC(p);
68 if (pc->pc_curthread == NULL) {
69 pc->pc_curthread = pc->pc_idlethread;
70 pc->pc_idlethread->td_critnest = 0;
71 }
72 #else
73 error = kthread_create(idle_proc, NULL, &p,
74 RFSTOPPED | RFHIGHPID, 0, "idle");
75 PCPU_SET(idlethread, FIRST_THREAD_IN_PROC(p));
76 #endif
77 if (error)
78 panic("idle_setup: kthread_create error %d\n", error);
79
80 PROC_LOCK(p);
81 p->p_flag |= P_NOLOAD;
82 mtx_lock_spin(&sched_lock);
83 td = FIRST_THREAD_IN_PROC(p);
84 TD_SET_CAN_RUN(td);
85 td->td_flags |= TDF_IDLETD;
86 sched_class(td->td_ksegrp, PRI_IDLE);
87 td->td_ksegrp->kg_user_pri = PRI_MAX_IDLE;
88 sched_prio(td, PRI_MAX_IDLE);
89 mtx_unlock_spin(&sched_lock);
90 PROC_UNLOCK(p);
91 #ifdef SMP
92 }
93 #endif
94 }
95
96 /*
97 * The actual idle process.
98 */
99 static void
100 idle_proc(void *dummy)
101 {
102 struct proc *p;
103 struct thread *td;
104 #ifdef SMP
105 cpumask_t mycpu;
106 #endif
107
108 td = curthread;
109 p = td->td_proc;
110 #ifdef SMP
111 mycpu = PCPU_GET(cpumask);
112 mtx_lock_spin(&sched_lock);
113 idle_cpus_mask |= mycpu;
114 mtx_unlock_spin(&sched_lock);
115 #endif
116 for (;;) {
117 mtx_assert(&Giant, MA_NOTOWNED);
118
119 while (sched_runnable() == 0)
120 cpu_idle();
121
122 mtx_lock_spin(&sched_lock);
123 #ifdef SMP
124 idle_cpus_mask &= ~mycpu;
125 #endif
126 mi_switch(SW_VOL, NULL);
127 #ifdef SMP
128 idle_cpus_mask |= mycpu;
129 #endif
130 mtx_unlock_spin(&sched_lock);
131 }
132 }
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