kern_idle.c revision 99942 
1/*-
2 * Copyright (c) 2000, All rights reserved.  See /usr/src/COPYRIGHT
3 *
4 * $FreeBSD: head/sys/kern/kern_idle.c 99942 2002-07-14 03:43:33Z julian $
5 */
6
7#include "opt_ktrace.h"
8
9#include <sys/param.h>
10#include <sys/systm.h>
11#include <sys/kernel.h>
12#include <sys/ktr.h>
13#include <sys/kthread.h>
14#include <sys/lock.h>
15#include <sys/mutex.h>
16#include <sys/pcpu.h>
17#include <sys/proc.h>
18#include <sys/resourcevar.h>
19#include <sys/smp.h>
20#include <sys/unistd.h>
21#ifdef KTRACE
22#include <sys/uio.h>
23#include <sys/ktrace.h>
24#endif
25
26static void idle_setup(void *dummy);
27SYSINIT(idle_setup, SI_SUB_SCHED_IDLE, SI_ORDER_FIRST, idle_setup, NULL)
28
29static void idle_proc(void *dummy);
30
31/*
32 * Setup per-cpu idle process contexts.  The AP's shouldn't be running or
33 * accessing their idle processes at this point, so don't bother with
34 * locking.
35 */
36static void
37idle_setup(void *dummy)
38{
39#ifdef SMP
40	struct pcpu *pc;
41#endif
42	struct proc *p;
43	struct thread *td;
44	int error;
45
46#ifdef SMP
47	SLIST_FOREACH(pc, &cpuhead, pc_allcpu) {
48		error = kthread_create(idle_proc, NULL, &p,
49		    RFSTOPPED | RFHIGHPID, "idle: cpu%d", pc->pc_cpuid);
50		pc->pc_idlethread = FIRST_THREAD_IN_PROC(p);
51		if (pc->pc_curthread == NULL) {
52			pc->pc_curthread = pc->pc_idlethread;
53			pc->pc_idlethread->td_critnest = 0;
54		}
55#else
56		error = kthread_create(idle_proc, NULL, &p,
57		    RFSTOPPED | RFHIGHPID, "idle");
58		PCPU_SET(idlethread, FIRST_THREAD_IN_PROC(p));
59#endif
60		if (error)
61			panic("idle_setup: kthread_create error %d\n", error);
62
63		p->p_flag |= P_NOLOAD;
64		td = FIRST_THREAD_IN_PROC(p);
65		td->td_state = TDS_UNQUEUED;
66		td->td_kse->ke_flags |= KEF_IDLEKSE;
67#ifdef SMP
68	}
69#endif
70}
71
72/*
73 * idle process context
74 */
75static void
76idle_proc(void *dummy)
77{
78#ifdef DIAGNOSTIC
79	int count;
80#endif
81	struct thread *td;
82	struct proc *p;
83
84	td = curthread;
85	p = td->td_proc;
86	for (;;) {
87		mtx_assert(&Giant, MA_NOTOWNED);
88
89#ifdef DIAGNOSTIC
90		count = 0;
91
92		while (count >= 0 && kserunnable() == 0) {
93#else
94		while (kserunnable() == 0) {
95#endif
96		/*
97		 * This is a good place to put things to be done in
98		 * the background, including sanity checks.
99		 */
100
101#ifdef DIAGNOSTIC
102			if (count++ < 0)
103				CTR0(KTR_PROC, "idle_proc: timed out waiting"
104				    " for a process");
105#endif
106
107#ifdef __i386__
108			cpu_idle();
109#endif
110		}
111
112		mtx_lock_spin(&sched_lock);
113		p->p_stats->p_ru.ru_nvcsw++;
114		mi_switch();
115		mtx_unlock_spin(&sched_lock);
116	}
117}
118