lib/libc/gen/getloadavg.c

   1 /*      $NetBSD: getloadavg.c,v 1.14 2012/03/13 21:13:36 christos Exp $ */
   2
   3 /*-
   4  * Copyright (c) 1989, 1993
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  * 3. Neither the name of the University nor the names of its contributors
  16  *    may be used to endorse or promote products derived from this software
  17  *    without specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  29  * SUCH DAMAGE.
  30  */
  31
  32 #include <sys/cdefs.h>
  33 #if defined(LIBC_SCCS) && !defined(lint)
  34 #if 0
  35 static char sccsid[] = "@(#)getloadavg.c        8.1 (Berkeley) 6/4/93";
  36 #else
  37 __RCSID("$NetBSD: getloadavg.c,v 1.14 2012/03/13 21:13:36 christos Exp $");
  38 #endif
  39 #endif /* LIBC_SCCS and not lint */
  40
  41 #include "namespace.h"
  42 #include <sys/param.h>
  43 #include <sys/time.h>
  44 #include <sys/resource.h>
  45 #include <sys/sysctl.h>
  46 #include <uvm/uvm_param.h>
  47
  48 #include <assert.h>
  49 #include <errno.h>
  50 #include <stdlib.h>
  51
  52 #ifdef __weak_alias
  53 __weak_alias(getloadavg,_getloadavg)
  54 #endif
  55
  56 /*
  57  * getloadavg() -- Get system load averages.
  58  *
  59  * Put `nelem' samples into `loadavg' array.
  60  * Return number of samples retrieved, or -1 on error.
  61  */
  62 int
  63 getloadavg(double loadavg[], int nelem)
  64 {
  65         struct loadavg loadinfo;
  66         static const int mib[] = { CTL_VM, VM_LOADAVG };
  67         size_t size, i;
  68
  69         _DIAGASSERT(loadavg != NULL);
  70         _DIAGASSERT(nelem >= 0);
  71
  72         size = sizeof(loadinfo);
  73         if (sysctl(mib, (u_int)__arraycount(mib), &loadinfo, &size, NULL, 0)
  74             == -1)
  75                 return -1;
  76
  77         size = MIN((size_t)nelem, __arraycount(loadinfo.ldavg));
  78         for (i = 0; i < size; i++)
  79                 loadavg[i] = (double) loadinfo.ldavg[i] / loadinfo.fscale;
  80         return nelem;
  81 }