lib/libkvm/kvm_getloadavg.c

   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. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  *
  29  * @(#)kvm_getloadavg.c 8.1 (Berkeley) 6/4/93
  30  * $FreeBSD: src/lib/libkvm/kvm_getloadavg.c,v 1.3 1999/12/27 07:14:57 peter Exp $
  31  */
  32
  33 #include <sys/param.h>
  34 #include <sys/time.h>
  35 #include <sys/resource.h>
  36 #include <sys/sysctl.h>
  37 #include <vm/vm_param.h>
  38
  39 #include <stdlib.h>
  40 #include <fcntl.h>
  41 #include <limits.h>
  42 #include <nlist.h>
  43
  44 #include "kvm.h"
  45 #include "kvm_private.h"
  46
  47 static struct nlist nl[] = {
  48         { .n_name = "_averunnable" },
  49 #define X_AVERUNNABLE   0
  50         { .n_name = "_fscale" },
  51 #define X_FSCALE        1
  52         { .n_name = "" },
  53 };
  54
  55 /*
  56  * kvm_getloadavg() -- Get system load averages, from live or dead kernels.
  57  *
  58  * Put `nelem' samples into `loadavg' array.
  59  * Return number of samples retrieved, or -1 on error.
  60  */
  61 int
  62 kvm_getloadavg(kvm_t *kd, double loadavg[], int nelem)
  63 {
  64         struct loadavg loadinfo;
  65         struct nlist *p;
  66         int fscale, i;
  67
  68         if (kvm_ishost(kd))
  69                 return (getloadavg(loadavg, nelem));
  70
  71         if (kvm_nlist(kd, nl) != 0) {
  72                 for (p = nl; p->n_type != 0; ++p);
  73                 _kvm_err(kd, kd->program,
  74                     "%s: no such symbol", p->n_name);
  75                 return (-1);
  76         }
  77
  78 #define KREAD(kd, addr, obj) \
  79         (kvm_read(kd, addr, (char *)(obj), sizeof(*obj)) != sizeof(*obj))
  80         if (KREAD(kd, nl[X_AVERUNNABLE].n_value, &loadinfo)) {
  81                 _kvm_err(kd, kd->program, "can't read averunnable");
  82                 return (-1);
  83         }
  84
  85         /*
  86          * Old kernels have fscale separately; if not found assume
  87          * running new format.
  88          */
  89         if (!KREAD(kd, nl[X_FSCALE].n_value, &fscale))
  90                 loadinfo.fscale = fscale;
  91
  92         nelem = MIN((size_t)nelem, sizeof(loadinfo.ldavg) / sizeof(__uint64_t));
  93         for (i = 0; i < nelem; i++)
  94                 loadavg[i] = (double) loadinfo.ldavg[i] / loadinfo.fscale;
  95         return (nelem);
  96 }