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  * 4. 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
  30 #include <sys/cdefs.h>
  31 __FBSDID("$FreeBSD$");
  32
  33 #if defined(LIBC_SCCS) && !defined(lint)
  34 #if 0
  35 static char sccsid[] = "@(#)kvm_getloadavg.c    8.1 (Berkeley) 6/4/93";
  36 #endif
  37 #endif /* LIBC_SCCS and not lint */
  38
  39 #include <sys/param.h>
  40 #include <sys/time.h>
  41 #include <sys/resource.h>
  42
  43 #include <stdlib.h>
  44 #include <limits.h>
  45 #include <nlist.h>
  46 #include <kvm.h>
  47
  48 #include "kvm_private.h"
  49
  50 static struct nlist nl[] = {
  51         { .n_name = "_averunnable" },
  52 #define X_AVERUNNABLE   0
  53         { .n_name = "_fscale" },
  54 #define X_FSCALE        1
  55         { .n_name = "" },
  56 };
  57
  58 /*
  59  * kvm_getloadavg() -- Get system load averages, from live or dead kernels.
  60  *
  61  * Put `nelem' samples into `loadavg' array.
  62  * Return number of samples retrieved, or -1 on error.
  63  */
  64 int
  65 kvm_getloadavg(kvm_t *kd, double loadavg[], int nelem)
  66 {
  67         struct loadavg loadinfo;
  68         struct nlist *p;
  69         int fscale, i;
  70
  71         if (ISALIVE(kd))
  72                 return (getloadavg(loadavg, nelem));
  73
  74         if (!kd->arch->ka_native(kd)) {
  75                 _kvm_err(kd, kd->program,
  76                     "cannot read loadavg from non-native core");
  77                 return (-1);
  78         }
  79
  80         if (kvm_nlist(kd, nl) != 0) {
  81                 for (p = nl; p->n_type != 0; ++p);
  82                 _kvm_err(kd, kd->program,
  83                     "%s: no such symbol", p->n_name);
  84                 return (-1);
  85         }
  86
  87 #define KREAD(kd, addr, obj) \
  88         (kvm_read(kd, addr, (char *)(obj), sizeof(*obj)) != sizeof(*obj))
  89         if (KREAD(kd, nl[X_AVERUNNABLE].n_value, &loadinfo)) {
  90                 _kvm_err(kd, kd->program, "can't read averunnable");
  91                 return (-1);
  92         }
  93
  94         /*
  95          * Old kernels have fscale separately; if not found assume
  96          * running new format.
  97          */
  98         if (!KREAD(kd, nl[X_FSCALE].n_value, &fscale))
  99                 loadinfo.fscale = fscale;
 100
 101         nelem = MIN(nelem, (int)(sizeof(loadinfo.ldavg) / sizeof(fixpt_t)));
 102         for (i = 0; i < nelem; i++)
 103                 loadavg[i] = (double) loadinfo.ldavg[i] / loadinfo.fscale;
 104         return (nelem);
 105 }