kern_idle.c revision 114471 
1/*-
2 * Copyright (c) 2000, All rights reserved.  See /usr/src/COPYRIGHT
3 *
4 * $FreeBSD: head/sys/kern/kern_idle.c 114471 2003-05-02 00:33:12Z 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/sched.h>
20#include <sys/smp.h>
21#include <sys/unistd.h>
22#ifdef KTRACE
23#include <sys/uio.h>
24#include <sys/ktrace.h>
25#endif
26
27static void idle_setup(void *dummy);
28SYSINIT(idle_setup, SI_SUB_SCHED_IDLE, SI_ORDER_FIRST, idle_setup, NULL)
29
30static void idle_proc(void *dummy);
31
32/*
33 * Setup per-cpu idle process contexts.  The AP's shouldn't be running or
34 * accessing their idle processes at this point, so don't bother with
35 * locking.
36 */
37static void
38idle_setup(void *dummy)
39{
40#ifdef SMP
41	struct pcpu *pc;
42#endif
43	struct proc *p;
44	struct thread *td;
45	int error;
46
47#ifdef SMP
48	SLIST_FOREACH(pc, &cpuhead, pc_allcpu) {
49		error = kthread_create(idle_proc, NULL, &p,
50		    RFSTOPPED | RFHIGHPID, 0, "idle: cpu%d", pc->pc_cpuid);
51		pc->pc_idlethread = FIRST_THREAD_IN_PROC(p);
52		if (pc->pc_curthread == NULL) {
53			pc->pc_curthread = pc->pc_idlethread;
54			pc->pc_idlethread->td_critnest = 0;
55		}
56#else
57		error = kthread_create(idle_proc, NULL, &p,
58		    RFSTOPPED | RFHIGHPID, 0, "idle");
59		PCPU_SET(idlethread, FIRST_THREAD_IN_PROC(p));
60#endif
61		if (error)
62			panic("idle_setup: kthread_create error %d\n", error);
63
64		PROC_LOCK(p);
65		p->p_flag |= P_NOLOAD;
66		mtx_lock_spin(&sched_lock);
67		p->p_state = PRS_NORMAL;
68		td = FIRST_THREAD_IN_PROC(p);
69		td->td_state = TDS_CAN_RUN;
70		td->td_flags |= TDF_IDLETD;
71		mtx_unlock_spin(&sched_lock);
72		PROC_UNLOCK(p);
73#ifdef SMP
74	}
75#endif
76}
77
78/*
79 * idle process context
80 */
81static void
82idle_proc(void *dummy)
83{
84#ifdef DIAGNOSTIC
85	int count;
86#endif
87	struct thread *td;
88	struct proc *p;
89
90	td = curthread;
91	p = td->td_proc;
92	for (;;) {
93		mtx_assert(&Giant, MA_NOTOWNED);
94
95#ifdef DIAGNOSTIC
96		count = 0;
97
98		while (count >= 0 && sched_runnable() == 0) {
99#else
100		while (sched_runnable() == 0) {
101#endif
102		/*
103		 * This is a good place to put things to be done in
104		 * the background, including sanity checks.
105		 */
106
107#ifdef DIAGNOSTIC
108			if (count++ < 0)
109				CTR0(KTR_PROC, "idle_proc: timed out waiting"
110				    " for a process");
111#endif
112
113#ifdef __i386__
114			cpu_idle();
115#endif
116		}
117
118		mtx_lock_spin(&sched_lock);
119		p->p_stats->p_ru.ru_nvcsw++;
120		td->td_state = TDS_CAN_RUN;
121		mi_switch();
122		mtx_unlock_spin(&sched_lock);
123	}
124}
125