kern_idle.c revision 67365 
1/*-
2 * Copyright (c) 2000, All rights reserved.  See /usr/src/COPYRIGHT
3 *
4 * $FreeBSD: head/sys/kern/kern_idle.c 67365 2000-10-20 07:58:15Z jhb $
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
45 */
46static void
47idle_setup(void *dummy)
48{
49	struct globaldata *gd;
50	int error;
51
52	SLIST_FOREACH(gd, &cpuhead, gd_allcpu) {
53#ifdef SMP
54		error = kthread_create(idle_proc, NULL, &gd->gd_idleproc,
55				       RFSTOPPED|RFHIGHPID, "idle: cpu%d",
56				       gd->gd_cpuid);
57#else
58		error = kthread_create(idle_proc, NULL, &gd->gd_idleproc,
59				       RFSTOPPED|RFHIGHPID, "idle");
60#endif
61		if (error)
62			panic("idle_setup: kthread_create error %d\n", error);
63
64		gd->gd_idleproc->p_flag |= P_NOLOAD;
65		gd->gd_idleproc->p_stat = SRUN;
66	}
67}
68
69/*
70 * idle process context
71 */
72static void
73idle_proc(void *dummy)
74{
75#ifdef DIAGNOSTIC
76	int count;
77#endif
78
79	for (;;) {
80		mtx_assert(&Giant, MA_NOTOWNED);
81
82#ifdef DIAGNOSTIC
83		count = 0;
84
85		while (count >= 0 && procrunnable() == 0) {
86#else
87		while (procrunnable() == 0) {
88#endif
89		/*
90		 * This is a good place to put things to be done in
91		 * the background, including sanity checks.
92		 */
93
94#ifdef DIAGNOSTIC
95			if (count++ < 0)
96				CTR0(KTR_PROC, "idle_proc: timed out waiting"
97				    " for a process");
98#endif
99
100			if (vm_page_zero_idle() != 0)
101				continue;
102
103#ifdef __i386__
104			cpu_idle();
105#endif
106		}
107
108		mtx_enter(&sched_lock, MTX_SPIN);
109		mi_switch();
110		mtx_exit(&sched_lock, MTX_SPIN);
111	}
112}
113