kernel/os/vm_meter.c

   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 #define UsefulPagesPerIO        nz((MAXBSIZE/PAGESIZE)/2)
  58
  59 extern int dopageout;
  60
  61 /* Average new into old with aging factor time */
  62 #define ave(smooth, cnt, time) \
  63         smooth = ((time - 1) * (smooth) + (cnt)) / (time)
  64
  65 /*
  66  * pagein and pageout rates for use by swapper.
  67  */
  68 ulong_t pginrate;               /* 5 second average     */
  69 ulong_t pgoutrate;              /* 5 second average     */
  70
  71 static ulong_t ogpagein;        /* pagein rate a sec ago */
  72 static ulong_t ogpageout;       /* pageout rate a sec ago */
  73
  74 /*
  75  * Called once a second to gather statistics.
  76  */
  77 void
  78 vmmeter(void)
  79 {
  80         cpu_t *cp;
  81         ulong_t gpagein, gpageout;
  82
  83         /*
  84          * Compute 5 sec and 30 sec average free memory values.
  85          */
  86         ave(avefree, freemem, 5);
  87         ave(avefree30, freemem, 30);
  88
  89         /*
  90          * Compute the 5 secs average of pageins and pageouts.
  91          */
  92         gpagein = gpageout = 0;
  93
  94         cp = cpu_list;
  95         do {
  96                 gpagein += (ulong_t)CPU_STATS(cp, vm.pgin);
  97                 gpageout += (ulong_t)CPU_STATS(cp, vm.pgout);
  98         } while ((cp = cp->cpu_next) != cpu_list);
  99
 100         if ((gpagein >= ogpagein) && (gpageout >= ogpageout)) {
 101                 ave(pginrate, gpagein - ogpagein, 5);
 102                 ave(pgoutrate, gpageout - ogpageout, 5);
 103         }
 104
 105         /*
 106          * Save the current pagein/pageout values.
 107          */
 108         ogpagein = gpagein;
 109         ogpageout = gpageout;
 110
 111         if (!lotsfree || !dopageout)
 112                 return;
 113
 114         /*
 115          * Decay deficit by the expected number of pages brought in since
 116          * the last call (i.e., in the last second).  The calculation
 117          * assumes that one half of the pages brought in are actually
 118          * useful (see comment above), and that half of the overall
 119          * paging i/o activity is pageins as opposed to pageouts (the
 120          * trailing factor of 2)  It also assumes that paging i/o is done
 121          * in units of MAXBSIZE bytes, which is a dubious assumption to
 122          * apply to all file system types.
 123          */
 124         deficit -= MIN(deficit,
 125             MAX(deficit / 10, UsefulPagesPerIO * maxpgio / 2));
 126 }