kern_idle.c revision 163709 
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 163709 2006-10-26 21:42:22Z jb $");
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#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 */
98static void
99idle_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#ifdef KSE
126		mi_switch(SW_VOL, NULL);
127#else
128		if ((td = choosethread()) != curthread)
129			mi_switch(SW_VOL, td);
130#endif
131#ifdef SMP
132		idle_cpus_mask |= mycpu;
133#endif
134		mtx_unlock_spin(&sched_lock);
135	}
136}
137