xref: /freebsd/sys/kern/kern_idle.c (revision 812fb4a89fc46249c08964142d5f873c51504f04)
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 #ifdef KSE
83 		sched_class(td->td_ksegrp, PRI_IDLE);
84 #else
85 		sched_class(td, PRI_IDLE);
86 #endif
87 		sched_prio(td, PRI_MAX_IDLE);
88 		mtx_unlock_spin(&sched_lock);
89 		PROC_UNLOCK(p);
90 #ifdef SMP
91 	}
92 #endif
93 }
94 
95 /*
96  * The actual idle process.
97  */
98 static void
99 idle_proc(void *dummy)
100 {
101 	struct proc *p;
102 	struct thread *td;
103 #ifdef SMP
104 	cpumask_t mycpu;
105 #endif
106 
107 	td = curthread;
108 	p = td->td_proc;
109 #ifdef SMP
110 	mycpu = PCPU_GET(cpumask);
111 	mtx_lock_spin(&sched_lock);
112 	idle_cpus_mask |= mycpu;
113 	mtx_unlock_spin(&sched_lock);
114 #endif
115 	for (;;) {
116 		mtx_assert(&Giant, MA_NOTOWNED);
117 
118 		while (sched_runnable() == 0)
119 			cpu_idle();
120 
121 		mtx_lock_spin(&sched_lock);
122 #ifdef SMP
123 		idle_cpus_mask &= ~mycpu;
124 #endif
125 		mi_switch(SW_VOL, NULL);
126 #ifdef SMP
127 		idle_cpus_mask |= mycpu;
128 #endif
129 		mtx_unlock_spin(&sched_lock);
130 	}
131 }
132