kvm_getloadavg.c revision 83551 
1/*-
2 * Copyright (c) 1993
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 * 3. All advertising materials mentioning features or use of this software
14 *    must display the following acknowledgement:
15 *	This product includes software developed by the University of
16 *	California, Berkeley and its contributors.
17 * 4. Neither the name of the University nor the names of its contributors
18 *    may be used to endorse or promote products derived from this software
19 *    without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33
34#include <sys/cdefs.h>
35__FBSDID("$FreeBSD: head/lib/libkvm/kvm_getloadavg.c 83551 2001-09-16 21:35:07Z dillon $");
36
37#if defined(LIBC_SCCS) && !defined(lint)
38#if 0
39static char sccsid[] = "@(#)kvm_getloadavg.c	8.1 (Berkeley) 6/4/93";
40#endif
41#endif /* LIBC_SCCS and not lint */
42
43#include <sys/param.h>
44#include <sys/lock.h>
45#include <sys/mutex.h>
46#include <sys/time.h>
47#include <sys/resource.h>
48#include <sys/proc.h>
49#include <sys/sysctl.h>
50#include <vm/vm_param.h>
51
52#include <stdlib.h>
53#include <fcntl.h>
54#include <limits.h>
55#include <nlist.h>
56#include <kvm.h>
57
58#include "kvm_private.h"
59
60static struct nlist nl[] = {
61	{ "_averunnable" },
62#define	X_AVERUNNABLE	0
63	{ "_fscale" },
64#define	X_FSCALE	1
65	{ "" },
66};
67
68/*
69 * kvm_getloadavg() -- Get system load averages, from live or dead kernels.
70 *
71 * Put `nelem' samples into `loadavg' array.
72 * Return number of samples retrieved, or -1 on error.
73 */
74int
75kvm_getloadavg(kd, loadavg, nelem)
76	kvm_t *kd;
77	double loadavg[];
78	int nelem;
79{
80	struct loadavg loadinfo;
81	struct nlist *p;
82	int fscale, i;
83
84	if (ISALIVE(kd))
85		return (getloadavg(loadavg, nelem));
86
87	if (kvm_nlist(kd, nl) != 0) {
88		for (p = nl; p->n_type != 0; ++p);
89		_kvm_err(kd, kd->program,
90		    "%s: no such symbol", p->n_name);
91		return (-1);
92	}
93
94#define KREAD(kd, addr, obj) \
95	(kvm_read(kd, addr, (char *)(obj), sizeof(*obj)) != sizeof(*obj))
96	if (KREAD(kd, nl[X_AVERUNNABLE].n_value, &loadinfo)) {
97		_kvm_err(kd, kd->program, "can't read averunnable");
98		return (-1);
99	}
100
101	/*
102	 * Old kernels have fscale separately; if not found assume
103	 * running new format.
104	 */
105	if (!KREAD(kd, nl[X_FSCALE].n_value, &fscale))
106		loadinfo.fscale = fscale;
107
108	nelem = MIN(nelem, sizeof(loadinfo.ldavg) / sizeof(fixpt_t));
109	for (i = 0; i < nelem; i++)
110		loadavg[i] = (double) loadinfo.ldavg[i] / loadinfo.fscale;
111	return (nelem);
112}
113