kern_idle.c revision 67297 
1/*-
2 * Copyright (c) 2000, All rights reserved.  See /usr/src/COPYRIGHT
3 *
4 * $FreeBSD: head/sys/kern/kern_idle.c 67297 2000-10-18 17:56:06Z peter $
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/queue.h>
22#include <sys/eventhandler.h>
23#include <vm/vm.h>
24#include <vm/vm_extern.h>
25#ifdef KTRACE
26#include <sys/uio.h>
27#include <sys/ktrace.h>
28#endif
29
30#include <machine/cpu.h>
31#include <machine/md_var.h>
32#include <machine/mutex.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
43EVENTHANDLER_FAST_DEFINE(idle_event, idle_eventhandler_t);
44
45/*
46 * setup per-cpu idle process contexts
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	}
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 (vm_page_zero_idle() != 0)
103				continue;
104
105			/* call out to any cpu-becoming-idle events */
106			EVENTHANDLER_FAST_INVOKE(idle_event, 0);
107		}
108
109		mtx_enter(&sched_lock, MTX_SPIN);
110		mi_switch();
111		mtx_exit(&sched_lock, MTX_SPIN);
112	}
113}
114