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FreeBSD/Linux Kernel Cross Reference
sys/kern/subr_param.c

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    1 /*-
    2  * Copyright (c) 1980, 1986, 1989, 1993
    3  *      The Regents of the University of California.  All rights reserved.
    4  * (c) UNIX System Laboratories, Inc.
    5  * All or some portions of this file are derived from material licensed
    6  * to the University of California by American Telephone and Telegraph
    7  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
    8  * the permission of UNIX System Laboratories, Inc.
    9  *
   10  * Redistribution and use in source and binary forms, with or without
   11  * modification, are permitted provided that the following conditions
   12  * are met:
   13  * 1. Redistributions of source code must retain the above copyright
   14  *    notice, this list of conditions and the following disclaimer.
   15  * 2. Redistributions in binary form must reproduce the above copyright
   16  *    notice, this list of conditions and the following disclaimer in the
   17  *    documentation and/or other materials provided with the distribution.
   18  * 4. Neither the name of the University nor the names of its contributors
   19  *    may be used to endorse or promote products derived from this software
   20  *    without specific prior written permission.
   21  *
   22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   32  * SUCH DAMAGE.
   33  *
   34  *      @(#)param.c     8.3 (Berkeley) 8/20/94
   35  */
   36 
   37 #include <sys/cdefs.h>
   38 __FBSDID("$FreeBSD: releng/8.2/sys/kern/subr_param.c 211891 2010-08-27 18:55:24Z jhb $");
   39 
   40 #include "opt_param.h"
   41 #include "opt_maxusers.h"
   42 
   43 #include <sys/limits.h>
   44 #include <sys/param.h>
   45 #include <sys/systm.h>
   46 #include <sys/kernel.h>
   47 #include <sys/sysctl.h>
   48 
   49 #include <vm/vm_param.h>
   50 
   51 /*
   52  * System parameter formulae.
   53  */
   54 
   55 #ifndef HZ
   56 #  if defined(__mips__) || defined(__arm__)
   57 #    define     HZ 100
   58 #  else
   59 #    define     HZ 1000
   60 #  endif
   61 #  ifndef HZ_VM
   62 #    define     HZ_VM 100
   63 #  endif
   64 #else
   65 #  ifndef HZ_VM
   66 #    define     HZ_VM HZ
   67 #  endif
   68 #endif
   69 #define NPROC (20 + 16 * maxusers)
   70 #ifndef NBUF
   71 #define NBUF 0
   72 #endif
   73 #ifndef MAXFILES
   74 #define MAXFILES (maxproc * 2)
   75 #endif
   76 
   77 static int sysctl_kern_vm_guest(SYSCTL_HANDLER_ARGS);
   78 
   79 int     hz;
   80 int     tick;
   81 int     maxusers;                       /* base tunable */
   82 int     maxproc;                        /* maximum # of processes */
   83 int     maxprocperuid;                  /* max # of procs per user */
   84 int     maxfiles;                       /* sys. wide open files limit */
   85 int     maxfilesperproc;                /* per-proc open files limit */
   86 int     ncallout;                       /* maximum # of timer events */
   87 int     nbuf;
   88 int     ngroups_max;                    /* max # groups per process */
   89 int     nswbuf;
   90 long    maxswzone;                      /* max swmeta KVA storage */
   91 long    maxbcache;                      /* max buffer cache KVA storage */
   92 long    maxpipekva;                     /* Limit on pipe KVA */
   93 int     vm_guest;                       /* Running as virtual machine guest? */
   94 u_long  maxtsiz;                        /* max text size */
   95 u_long  dfldsiz;                        /* initial data size limit */
   96 u_long  maxdsiz;                        /* max data size */
   97 u_long  dflssiz;                        /* initial stack size limit */
   98 u_long  maxssiz;                        /* max stack size */
   99 u_long  sgrowsiz;                       /* amount to grow stack */
  100 
  101 SYSCTL_INT(_kern, OID_AUTO, hz, CTLFLAG_RDTUN, &hz, 0,
  102     "Number of clock ticks per second");
  103 SYSCTL_INT(_kern, OID_AUTO, ncallout, CTLFLAG_RDTUN, &ncallout, 0,
  104     "Number of pre-allocated timer events");
  105 SYSCTL_INT(_kern, OID_AUTO, nbuf, CTLFLAG_RDTUN, &nbuf, 0,
  106     "Number of buffers in the buffer cache");
  107 SYSCTL_INT(_kern, OID_AUTO, nswbuf, CTLFLAG_RDTUN, &nswbuf, 0,
  108     "Number of swap buffers");
  109 SYSCTL_LONG(_kern, OID_AUTO, maxswzone, CTLFLAG_RDTUN, &maxswzone, 0,
  110     "Maximum memory for swap metadata");
  111 SYSCTL_LONG(_kern, OID_AUTO, maxbcache, CTLFLAG_RDTUN, &maxbcache, 0,
  112     "Maximum value of vfs.maxbufspace");
  113 SYSCTL_ULONG(_kern, OID_AUTO, maxtsiz, CTLFLAG_RDTUN, &maxtsiz, 0,
  114     "Maximum text size");
  115 SYSCTL_ULONG(_kern, OID_AUTO, dfldsiz, CTLFLAG_RDTUN, &dfldsiz, 0,
  116     "Initial data size limit");
  117 SYSCTL_ULONG(_kern, OID_AUTO, maxdsiz, CTLFLAG_RDTUN, &maxdsiz, 0,
  118     "Maximum data size");
  119 SYSCTL_ULONG(_kern, OID_AUTO, dflssiz, CTLFLAG_RDTUN, &dflssiz, 0,
  120     "Initial stack size limit");
  121 SYSCTL_ULONG(_kern, OID_AUTO, maxssiz, CTLFLAG_RDTUN, &maxssiz, 0,
  122     "Maximum stack size");
  123 SYSCTL_ULONG(_kern, OID_AUTO, sgrowsiz, CTLFLAG_RDTUN, &sgrowsiz, 0,
  124     "Amount to grow stack on a stack fault");
  125 SYSCTL_PROC(_kern, OID_AUTO, vm_guest, CTLFLAG_RD | CTLTYPE_STRING,
  126     NULL, 0, sysctl_kern_vm_guest, "A",
  127     "Virtual machine guest detected? (none|generic|xen)");
  128 
  129 /*
  130  * These have to be allocated somewhere; allocating
  131  * them here forces loader errors if this file is omitted
  132  * (if they've been externed everywhere else; hah!).
  133  */
  134 struct  buf *swbuf;
  135 
  136 /*
  137  * The elements of this array are ordered based upon the values of the
  138  * corresponding enum VM_GUEST members.
  139  */
  140 static const char *const vm_guest_sysctl_names[] = {
  141         "none",
  142         "generic",
  143         "xen",
  144         NULL
  145 };
  146 
  147 #ifndef XEN
  148 static const char *const vm_bnames[] = {
  149         "QEMU",                         /* QEMU */
  150         "Plex86",                       /* Plex86 */
  151         "Bochs",                        /* Bochs */
  152         "Xen",                          /* Xen */
  153         NULL
  154 };
  155 
  156 static const char *const vm_pnames[] = {
  157         "VMware Virtual Platform",      /* VMWare VM */
  158         "Virtual Machine",              /* Microsoft VirtualPC */
  159         "VirtualBox",                   /* Sun xVM VirtualBox */
  160         "Parallels Virtual Platform",   /* Parallels VM */
  161         NULL
  162 };
  163 
  164 
  165 /*
  166  * Detect known Virtual Machine hosts by inspecting the emulated BIOS.
  167  */
  168 static enum VM_GUEST
  169 detect_virtual(void)
  170 {
  171         char *sysenv;
  172         int i;
  173 
  174         sysenv = getenv("smbios.bios.vendor");
  175         if (sysenv != NULL) {
  176                 for (i = 0; vm_bnames[i] != NULL; i++)
  177                         if (strcmp(sysenv, vm_bnames[i]) == 0) {
  178                                 freeenv(sysenv);
  179                                 return (VM_GUEST_VM);
  180                         }
  181                 freeenv(sysenv);
  182         }
  183         sysenv = getenv("smbios.system.product");
  184         if (sysenv != NULL) {
  185                 for (i = 0; vm_pnames[i] != NULL; i++)
  186                         if (strcmp(sysenv, vm_pnames[i]) == 0) {
  187                                 freeenv(sysenv);
  188                                 return (VM_GUEST_VM);
  189                         }
  190                 freeenv(sysenv);
  191         }
  192         return (VM_GUEST_NO);
  193 }
  194 #endif
  195 
  196 /*
  197  * Boot time overrides that are not scaled against main memory
  198  */
  199 void
  200 init_param1(void)
  201 {
  202 #ifndef XEN
  203         vm_guest = detect_virtual();
  204 #else
  205         vm_guest = VM_GUEST_XEN;
  206 #endif
  207         hz = -1;
  208         TUNABLE_INT_FETCH("kern.hz", &hz);
  209         if (hz == -1)
  210                 hz = vm_guest > VM_GUEST_NO ? HZ_VM : HZ;
  211         tick = 1000000 / hz;
  212 
  213 #ifdef VM_SWZONE_SIZE_MAX
  214         maxswzone = VM_SWZONE_SIZE_MAX;
  215 #endif
  216         TUNABLE_LONG_FETCH("kern.maxswzone", &maxswzone);
  217 #ifdef VM_BCACHE_SIZE_MAX
  218         maxbcache = VM_BCACHE_SIZE_MAX;
  219 #endif
  220         TUNABLE_LONG_FETCH("kern.maxbcache", &maxbcache);
  221 
  222         maxtsiz = MAXTSIZ;
  223         TUNABLE_ULONG_FETCH("kern.maxtsiz", &maxtsiz);
  224         dfldsiz = DFLDSIZ;
  225         TUNABLE_ULONG_FETCH("kern.dfldsiz", &dfldsiz);
  226         maxdsiz = MAXDSIZ;
  227         TUNABLE_ULONG_FETCH("kern.maxdsiz", &maxdsiz);
  228         dflssiz = DFLSSIZ;
  229         TUNABLE_ULONG_FETCH("kern.dflssiz", &dflssiz);
  230         maxssiz = MAXSSIZ;
  231         TUNABLE_ULONG_FETCH("kern.maxssiz", &maxssiz);
  232         sgrowsiz = SGROWSIZ;
  233         TUNABLE_ULONG_FETCH("kern.sgrowsiz", &sgrowsiz);
  234 
  235         /*
  236          * Let the administrator set {NGROUPS_MAX}, but disallow values
  237          * less than NGROUPS_MAX which would violate POSIX.1-2008 or
  238          * greater than INT_MAX-1 which would result in overflow.
  239          */
  240         ngroups_max = NGROUPS_MAX;
  241         TUNABLE_INT_FETCH("kern.ngroups", &ngroups_max);
  242         if (ngroups_max < NGROUPS_MAX)
  243                 ngroups_max = NGROUPS_MAX;
  244 }
  245 
  246 /*
  247  * Boot time overrides that are scaled against main memory
  248  */
  249 void
  250 init_param2(long physpages)
  251 {
  252 
  253         /* Base parameters */
  254         maxusers = MAXUSERS;
  255         TUNABLE_INT_FETCH("kern.maxusers", &maxusers);
  256         if (maxusers == 0) {
  257                 maxusers = physpages / (2 * 1024 * 1024 / PAGE_SIZE);
  258                 if (maxusers < 32)
  259                         maxusers = 32;
  260                 if (maxusers > 384)
  261                         maxusers = 384;
  262         }
  263 
  264         /*
  265          * The following can be overridden after boot via sysctl.  Note:
  266          * unless overriden, these macros are ultimately based on maxusers.
  267          */
  268         maxproc = NPROC;
  269         TUNABLE_INT_FETCH("kern.maxproc", &maxproc);
  270         /*
  271          * Limit maxproc so that kmap entries cannot be exhausted by
  272          * processes.
  273          */
  274         if (maxproc > (physpages / 12))
  275                 maxproc = physpages / 12;
  276         maxfiles = MAXFILES;
  277         TUNABLE_INT_FETCH("kern.maxfiles", &maxfiles);
  278         maxprocperuid = (maxproc * 9) / 10;
  279         maxfilesperproc = (maxfiles * 9) / 10;
  280         
  281         /*
  282          * Cannot be changed after boot.
  283          */
  284         nbuf = NBUF;
  285         TUNABLE_INT_FETCH("kern.nbuf", &nbuf);
  286 
  287         ncallout = 16 + maxproc + maxfiles;
  288         TUNABLE_INT_FETCH("kern.ncallout", &ncallout);
  289 }
  290 
  291 /*
  292  * Boot time overrides that are scaled against the kmem map
  293  */
  294 void
  295 init_param3(long kmempages)
  296 {
  297 
  298         /*
  299          * The default for maxpipekva is max(5% of the kmem map, 512KB).
  300          * See sys_pipe.c for more details.
  301          */
  302         maxpipekva = (kmempages / 20) * PAGE_SIZE;
  303         if (maxpipekva < 512 * 1024)
  304                 maxpipekva = 512 * 1024;
  305         TUNABLE_LONG_FETCH("kern.ipc.maxpipekva", &maxpipekva);
  306 }
  307 
  308 /*
  309  * Sysctl stringiying handler for kern.vm_guest.
  310  */
  311 static int
  312 sysctl_kern_vm_guest(SYSCTL_HANDLER_ARGS)
  313 {
  314         return (SYSCTL_OUT(req, vm_guest_sysctl_names[vm_guest], 
  315             strlen(vm_guest_sysctl_names[vm_guest])));
  316 }

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