kern_idle.c revision 72376 
1/*-
2 * Copyright (c) 2000, All rights reserved.  See /usr/src/COPYRIGHT
3 *
4 * $FreeBSD: head/sys/kern/kern_idle.c 72376 2001-02-12 00:20:08Z jake $
5 */
6
7#include "opt_ktrace.h"
8
9#include <sys/param.h>
10#include <sys/systm.h>
11#include <sys/proc.h>
12#include <sys/kernel.h>
13#include <sys/ktr.h>
14#include <sys/signalvar.h>
15#include <sys/resourcevar.h>
16#include <sys/vmmeter.h>
17#include <sys/sysctl.h>
18#include <sys/unistd.h>
19#include <sys/ipl.h>
20#include <sys/kthread.h>
21#include <sys/mutex.h>
22#include <sys/queue.h>
23#include <sys/eventhandler.h>
24#include <vm/vm.h>
25#include <vm/vm_extern.h>
26#ifdef KTRACE
27#include <sys/uio.h>
28#include <sys/ktrace.h>
29#endif
30
31#include <machine/cpu.h>
32#include <machine/md_var.h>
33#include <machine/smp.h>
34
35#include <machine/globaldata.h>
36#include <machine/globals.h>
37
38static void idle_setup(void *dummy);
39SYSINIT(idle_setup, SI_SUB_SCHED_IDLE, SI_ORDER_FIRST, idle_setup, NULL)
40
41static void idle_proc(void *dummy);
42
43/*
44 * Setup per-cpu idle process contexts.  The AP's shouldn't be running or
45 * accessing their idle processes at this point, so don't bother with
46 * locking.
47 */
48static void
49idle_setup(void *dummy)
50{
51	struct globaldata *gd;
52	int error;
53
54	SLIST_FOREACH(gd, &cpuhead, gd_allcpu) {
55#ifdef SMP
56		error = kthread_create(idle_proc, NULL, &gd->gd_idleproc,
57				       RFSTOPPED|RFHIGHPID, "idle: cpu%d",
58				       gd->gd_cpuid);
59#else
60		error = kthread_create(idle_proc, NULL, &gd->gd_idleproc,
61				       RFSTOPPED|RFHIGHPID, "idle");
62#endif
63		if (error)
64			panic("idle_setup: kthread_create error %d\n", error);
65
66		gd->gd_idleproc->p_flag |= P_NOLOAD;
67		gd->gd_idleproc->p_stat = SRUN;
68		if (gd->gd_curproc == NULL)
69			gd->gd_curproc = gd->gd_idleproc;
70	}
71}
72
73/*
74 * idle process context
75 */
76static void
77idle_proc(void *dummy)
78{
79#ifdef DIAGNOSTIC
80	int count;
81#endif
82
83	for (;;) {
84		mtx_assert(&Giant, MA_NOTOWNED);
85
86#ifdef DIAGNOSTIC
87		count = 0;
88
89		while (count >= 0 && procrunnable() == 0) {
90#else
91		while (procrunnable() == 0) {
92#endif
93		/*
94		 * This is a good place to put things to be done in
95		 * the background, including sanity checks.
96		 */
97
98#ifdef DIAGNOSTIC
99			if (count++ < 0)
100				CTR0(KTR_PROC, "idle_proc: timed out waiting"
101				    " for a process");
102#endif
103
104#if 0
105			if (vm_page_zero_idle() != 0)
106				continue;
107#endif
108
109#ifdef __i386__
110			cpu_idle();
111#endif
112		}
113
114		mtx_lock_spin(&sched_lock);
115		curproc->p_stats->p_ru.ru_nvcsw++;
116		mi_switch();
117		mtx_unlock_spin(&sched_lock);
118	}
119}
120