kern_idle.c revision 164936 
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: head/sys/kern/kern_idle.c 164936 2006-12-06 06:34:57Z julian $");
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
43static void idle_setup(void *dummy);
44SYSINIT(idle_setup, SI_SUB_SCHED_IDLE, SI_ORDER_FIRST, idle_setup, NULL)
45
46static 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 */
53static void
54idle_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, 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 */
94static void
95idle_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}
128