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 #else
69 error = kthread_create(idle_proc, NULL, &p,
70 RFSTOPPED | RFHIGHPID, 0, "idle");
71 PCPU_SET(idlethread, FIRST_THREAD_IN_PROC(p));
72 #endif
73 if (error)
74 panic("idle_setup: kthread_create error %d\n", error);
75
76 PROC_LOCK(p);
77 p->p_flag |= P_NOLOAD;
78 mtx_lock_spin(&sched_lock);
79 td = FIRST_THREAD_IN_PROC(p);
80 TD_SET_CAN_RUN(td);
81 td->td_flags |= TDF_IDLETD;
82 sched_class(td->td_ksegrp, PRI_IDLE);
83 sched_prio(td, PRI_MAX_IDLE);
84 mtx_unlock_spin(&sched_lock);
85 PROC_UNLOCK(p);
86 #ifdef SMP
87 }
88 #endif
89 }
90
91 /*
92 * The actual idle process.
93 */
94 static void
95 idle_proc(void *dummy)
96 {
97 struct proc *p;
98 struct thread *td;
99 #ifdef SMP
100 cpumask_t mycpu;
101 #endif
102
103 td = curthread;
104 p = td->td_proc;
105 #ifdef SMP
106 mycpu = PCPU_GET(cpumask);
107 mtx_lock_spin(&sched_lock);
108 idle_cpus_mask |= mycpu;
109 mtx_unlock_spin(&sched_lock);
110 #endif
111 for (;;) {
112 mtx_assert(&Giant, MA_NOTOWNED);
113
114 while (sched_runnable() == 0)
115 cpu_idle();
116
117 mtx_lock_spin(&sched_lock);
118 #ifdef SMP
119 idle_cpus_mask &= ~mycpu;
120 #endif
121 mi_switch(SW_VOL, NULL);
122 #ifdef SMP
123 idle_cpus_mask |= mycpu;
124 #endif
125 mtx_unlock_spin(&sched_lock);
126 }
127 }
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