kern_idle.c revision 76440 
1/*-
2 * Copyright (c) 2000, All rights reserved.  See /usr/src/COPYRIGHT
3 *
4 * $FreeBSD: head/sys/kern/kern_idle.c 76440 2001-05-10 17:45:49Z jhb $
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#if 0
22#include <vm/vm.h>
23#include <vm/vm_extern.h>
24#endif
25#ifdef KTRACE
26#include <sys/uio.h>
27#include <sys/ktrace.h>
28#endif
29
30static void idle_setup(void *dummy);
31SYSINIT(idle_setup, SI_SUB_SCHED_IDLE, SI_ORDER_FIRST, idle_setup, NULL)
32
33static void idle_proc(void *dummy);
34
35/*
36 * Setup per-cpu idle process contexts.  The AP's shouldn't be running or
37 * accessing their idle processes at this point, so don't bother with
38 * locking.
39 */
40static void
41idle_setup(void *dummy)
42{
43#ifdef SMP
44	struct globaldata *gd;
45#endif
46	struct proc *p;
47	int error;
48
49#ifdef SMP
50	SLIST_FOREACH(gd, &cpuhead, gd_allcpu) {
51		error = kthread_create(idle_proc, NULL, &p,
52		    RFSTOPPED | RFHIGHPID, "idle: cpu%d", gd->gd_cpuid);
53		gd->gd_idleproc = p;
54		if (gd->gd_curproc == NULL)
55			gd->gd_curproc = p;
56#else
57		error = kthread_create(idle_proc, NULL, &p,
58		    RFSTOPPED | RFHIGHPID, "idle");
59		PCPU_SET(idleproc, p);
60#endif
61		if (error)
62			panic("idle_setup: kthread_create error %d\n", error);
63
64		p->p_flag |= P_NOLOAD;
65		p->p_stat = SRUN;
66#ifdef SMP
67	}
68#endif
69}
70
71/*
72 * idle process context
73 */
74static void
75idle_proc(void *dummy)
76{
77#ifdef DIAGNOSTIC
78	int count;
79#endif
80
81	for (;;) {
82		mtx_assert(&Giant, MA_NOTOWNED);
83
84#ifdef DIAGNOSTIC
85		count = 0;
86
87		while (count >= 0 && procrunnable() == 0) {
88#else
89		while (procrunnable() == 0) {
90#endif
91		/*
92		 * This is a good place to put things to be done in
93		 * the background, including sanity checks.
94		 */
95
96#ifdef DIAGNOSTIC
97			if (count++ < 0)
98				CTR0(KTR_PROC, "idle_proc: timed out waiting"
99				    " for a process");
100#endif
101
102#if 0
103			if (vm_page_zero_idle() != 0)
104				continue;
105#endif
106
107#ifdef __i386__
108			cpu_idle();
109#endif
110		}
111
112		mtx_lock_spin(&sched_lock);
113		curproc->p_stats->p_ru.ru_nvcsw++;
114		mi_switch();
115		mtx_unlock_spin(&sched_lock);
116	}
117}
118