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getloadavg.c revision 1.1 
      1 /*-
      2  * Copyright (c) 1989 The Regents of the University of California.
      3  * 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 #if defined(LIBC_SCCS) && !defined(lint)
     35 static char sccsid[] = "@(#)getloadavg.c	6.2 (Berkeley) 6/29/90";
     36 #endif /* LIBC_SCCS and not lint */
     37 
     38 #include <sys/param.h>
     39 #include <sys/types.h>
     40 #include <sys/file.h>
     41 #include <nlist.h>
     42 
     43 static struct nlist nl[] = {
     44 	{ "_averunnable" },
     45 #define	X_AVERUNNABLE	0
     46 	{ "_fscale" },
     47 #define	X_FSCALE	1
     48 	{ "" },
     49 };
     50 
     51 /*
     52  *  getloadavg() -- Get system load averages.
     53  *
     54  *  Put `nelem' samples into `loadavg' array.
     55  *  Return number of samples retrieved, or -1 on error.
     56  */
     57 getloadavg(loadavg, nelem)
     58 	double loadavg[];
     59 	int nelem;
     60 {
     61 	static int need_nlist = 1;
     62 	fixpt_t	averunnable[3];
     63 	int fscale, kmemfd, i;
     64 	int alreadyopen;
     65 
     66 	if ((alreadyopen = kvm_openfiles(NULL, NULL, NULL)) == -1)
     67 		return (-1);
     68 	/*
     69 	 * cache nlist
     70 	 */
     71 	if (need_nlist) {
     72 		if (kvm_nlist(nl) != 0)
     73 			goto bad;
     74 		need_nlist = 0;
     75 	}
     76 	if (kvm_read((off_t)nl[X_AVERUNNABLE].n_value, (char *)averunnable,
     77 	    sizeof(averunnable)) != sizeof(averunnable))
     78 		goto bad;
     79 	if (kvm_read( (off_t)nl[X_FSCALE].n_value, (char *)&fscale,
     80 	    sizeof(fscale)) != sizeof(fscale))
     81 		goto bad;
     82 	nelem = MIN(nelem, sizeof(averunnable) / sizeof(averunnable[0]));
     83 	for (i = 0; i < nelem; i++)
     84 		loadavg[i] = (double) averunnable[i] / fscale;
     85 	if (!alreadyopen)
     86 		kvm_close();
     87 	return (nelem);
     88 
     89 bad:
     90 	if (!alreadyopen)
     91 		kvm_close();
     92 	return (-1);
     93 }
     94