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      1 /*
      2  * CDDL HEADER START
      3  *
      4  * The contents of this file are subject to the terms of the
      5  * Common Development and Distribution License, Version 1.0 only
      6  * (the "License").  You may not use this file except in compliance
      7  * with the License.
      8  *
      9  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
     10  * or http://www.opensolaris.org/os/licensing.
     11  * See the License for the specific language governing permissions
     12  * and limitations under the License.
     13  *
     14  * When distributing Covered Code, include this CDDL HEADER in each
     15  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
     16  * If applicable, add the following below this CDDL HEADER, with the
     17  * fields enclosed by brackets "[]" replaced with your own identifying
     18  * information: Portions Copyright [yyyy] [name of copyright owner]
     19  *
     20  * CDDL HEADER END
     21  */
     22 /*
     23  * Copyright 2002 Sun Microsystems, Inc.  All rights reserved.
     24  * Use is subject to license terms.
     25  */
     26 
     27 /*	Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T	*/
     28 /*	  All Rights Reserved  	*/
     29 
     30 /*
     31  * University Copyright- Copyright (c) 1982, 1986, 1988
     32  * The Regents of the University of California
     33  * All Rights Reserved
     34  *
     35  * University Acknowledgment- Portions of this document are derived from
     36  * software developed by the University of California, Berkeley, and its
     37  * contributors.
     38  */
     39 
     40 #pragma ident	"%Z%%M%	%I%	%E% SMI"
     41 
     42 #include <sys/types.h>
     43 #include <sys/param.h>
     44 #include <sys/sysmacros.h>
     45 #include <sys/systm.h>
     46 #include <sys/vmsystm.h>
     47 #include <sys/cpuvar.h>
     48 #include <sys/sysinfo.h>
     49 
     50 /*
     51  * This define represents the number of
     52  * useful pages transferred per paging i/o operation, under the assumption
     53  * that half of the total number is actually useful.  However, if there's
     54  * only one page transferred per operation, we assume that it's useful.
     55  */
     56 
     57 #ifdef	lint
     58 #define	UsefulPagesPerIO	1
     59 #else	/* lint */
     60 #define	UsefulPagesPerIO	nz((MAXBSIZE/PAGESIZE)/2)
     61 #endif	/* lint */
     62 
     63 extern int dopageout;
     64 
     65 /* Average new into old with aging factor time */
     66 #define	ave(smooth, cnt, time) \
     67 	smooth = ((time - 1) * (smooth) + (cnt)) / (time)
     68 
     69 /*
     70  * pagein and pageout rates for use by swapper.
     71  */
     72 ulong_t pginrate;		/* 5 second average	*/
     73 ulong_t pgoutrate;		/* 5 second average	*/
     74 
     75 static ulong_t ogpagein;	/* pagein rate a sec ago */
     76 static ulong_t ogpageout;	/* pageout rate a sec ago */
     77 
     78 /*
     79  * Called once a second to gather statistics.
     80  */
     81 void
     82 vmmeter(void)
     83 {
     84 	cpu_t *cp;
     85 	ulong_t gpagein, gpageout;
     86 
     87 	/*
     88 	 * Compute 5 sec and 30 sec average free memory values.
     89 	 */
     90 	ave(avefree, freemem, 5);
     91 	ave(avefree30, freemem, 30);
     92 
     93 	/*
     94 	 * Compute the 5 secs average of pageins and pageouts.
     95 	 */
     96 	gpagein = gpageout = 0;
     97 
     98 	cp = cpu_list;
     99 	do {
    100 		gpagein += (ulong_t)CPU_STATS(cp, vm.pgin);
    101 		gpageout += (ulong_t)CPU_STATS(cp, vm.pgout);
    102 	} while ((cp = cp->cpu_next) != cpu_list);
    103 
    104 	if ((gpagein >= ogpagein) && (gpageout >= ogpageout)) {
    105 		ave(pginrate, gpagein - ogpagein, 5);
    106 		ave(pgoutrate, gpageout - ogpageout, 5);
    107 	}
    108 
    109 	/*
    110 	 * Save the current pagein/pageout values.
    111 	 */
    112 	ogpagein = gpagein;
    113 	ogpageout = gpageout;
    114 
    115 	if (!lotsfree || !dopageout)
    116 		return;
    117 
    118 	/*
    119 	 * Decay deficit by the expected number of pages brought in since
    120 	 * the last call (i.e., in the last second).  The calculation
    121 	 * assumes that one half of the pages brought in are actually
    122 	 * useful (see comment above), and that half of the overall
    123 	 * paging i/o activity is pageins as opposed to pageouts (the
    124 	 * trailing factor of 2)  It also assumes that paging i/o is done
    125 	 * in units of MAXBSIZE bytes, which is a dubious assumption to
    126 	 * apply to all file system types.
    127 	 */
    128 	deficit -= MIN(deficit,
    129 	    MAX(deficit / 10, UsefulPagesPerIO * maxpgio / 2));
    130 }
    131