The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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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/8.4/sys/kern/subr_param.c 246401 2013-02-06 13:14:30Z zont $");
   39 
   40 #include "opt_param.h"
   41 #include "opt_msgbuf.h"
   42 #include "opt_maxusers.h"
   43 
   44 #include <sys/limits.h>
   45 #include <sys/param.h>
   46 #include <sys/systm.h>
   47 #include <sys/kernel.h>
   48 #include <sys/sysctl.h>
   49 #include <sys/msgbuf.h>
   50 
   51 #include <vm/vm_param.h>
   52 
   53 /*
   54  * System parameter formulae.
   55  */
   56 
   57 #ifndef HZ
   58 #  if defined(__mips__) || defined(__arm__)
   59 #    define     HZ 100
   60 #  else
   61 #    define     HZ 1000
   62 #  endif
   63 #  ifndef HZ_VM
   64 #    define     HZ_VM 100
   65 #  endif
   66 #else
   67 #  ifndef HZ_VM
   68 #    define     HZ_VM HZ
   69 #  endif
   70 #endif
   71 #define NPROC (20 + 16 * maxusers)
   72 #ifndef NBUF
   73 #define NBUF 0
   74 #endif
   75 #ifndef MAXFILES
   76 #define MAXFILES (maxproc * 2)
   77 #endif
   78 
   79 static int sysctl_kern_vm_guest(SYSCTL_HANDLER_ARGS);
   80 
   81 int     hz;
   82 int     tick;
   83 int     maxusers;                       /* base tunable */
   84 int     maxproc;                        /* maximum # of processes */
   85 int     maxprocperuid;                  /* max # of procs per user */
   86 int     maxfiles;                       /* sys. wide open files limit */
   87 int     maxfilesperproc;                /* per-proc open files limit */
   88 int     msgbufsize;                     /* size of kernel message buffer */
   89 int     ncallout;                       /* maximum # of timer events */
   90 int     nbuf;
   91 int     ngroups_max;                    /* max # groups per process */
   92 int     nswbuf;
   93 long    maxswzone;                      /* max swmeta KVA storage */
   94 long    maxbcache;                      /* max buffer cache KVA storage */
   95 long    maxpipekva;                     /* Limit on pipe KVA */
   96 int     vm_guest;                       /* Running as virtual machine guest? */
   97 u_long  maxtsiz;                        /* max text size */
   98 u_long  dfldsiz;                        /* initial data size limit */
   99 u_long  maxdsiz;                        /* max data size */
  100 u_long  dflssiz;                        /* initial stack size limit */
  101 u_long  maxssiz;                        /* max stack size */
  102 u_long  sgrowsiz;                       /* amount to grow stack */
  103 
  104 SYSCTL_INT(_kern, OID_AUTO, hz, CTLFLAG_RDTUN, &hz, 0,
  105     "Number of clock ticks per second");
  106 SYSCTL_INT(_kern, OID_AUTO, ncallout, CTLFLAG_RDTUN, &ncallout, 0,
  107     "Number of pre-allocated timer events");
  108 SYSCTL_INT(_kern, OID_AUTO, nbuf, CTLFLAG_RDTUN, &nbuf, 0,
  109     "Number of buffers in the buffer cache");
  110 SYSCTL_INT(_kern, OID_AUTO, nswbuf, CTLFLAG_RDTUN, &nswbuf, 0,
  111     "Number of swap buffers");
  112 SYSCTL_INT(_kern, OID_AUTO, msgbufsize, CTLFLAG_RDTUN, &msgbufsize, 0,
  113     "Size of the kernel message buffer");
  114 SYSCTL_LONG(_kern, OID_AUTO, maxswzone, CTLFLAG_RDTUN, &maxswzone, 0,
  115     "Maximum memory for swap metadata");
  116 SYSCTL_LONG(_kern, OID_AUTO, maxbcache, CTLFLAG_RDTUN, &maxbcache, 0,
  117     "Maximum value of vfs.maxbufspace");
  118 SYSCTL_ULONG(_kern, OID_AUTO, maxtsiz, CTLFLAG_RW | CTLFLAG_TUN, &maxtsiz, 0,
  119     "Maximum text size");
  120 SYSCTL_ULONG(_kern, OID_AUTO, dfldsiz, CTLFLAG_RW | CTLFLAG_TUN, &dfldsiz, 0,
  121     "Initial data size limit");
  122 SYSCTL_ULONG(_kern, OID_AUTO, maxdsiz, CTLFLAG_RW | CTLFLAG_TUN, &maxdsiz, 0,
  123     "Maximum data size");
  124 SYSCTL_ULONG(_kern, OID_AUTO, dflssiz, CTLFLAG_RW | CTLFLAG_TUN, &dflssiz, 0,
  125     "Initial stack size limit");
  126 SYSCTL_ULONG(_kern, OID_AUTO, maxssiz, CTLFLAG_RW | CTLFLAG_TUN, &maxssiz, 0,
  127     "Maximum stack size");
  128 SYSCTL_ULONG(_kern, OID_AUTO, sgrowsiz, CTLFLAG_RW | CTLFLAG_TUN, &sgrowsiz, 0,
  129     "Amount to grow stack on a stack fault");
  130 SYSCTL_PROC(_kern, OID_AUTO, vm_guest, CTLFLAG_RD | CTLTYPE_STRING,
  131     NULL, 0, sysctl_kern_vm_guest, "A",
  132     "Virtual machine guest detected? (none|generic|xen)");
  133 
  134 /*
  135  * These have to be allocated somewhere; allocating
  136  * them here forces loader errors if this file is omitted
  137  * (if they've been externed everywhere else; hah!).
  138  */
  139 struct  buf *swbuf;
  140 
  141 /*
  142  * The elements of this array are ordered based upon the values of the
  143  * corresponding enum VM_GUEST members.
  144  */
  145 static const char *const vm_guest_sysctl_names[] = {
  146         "none",
  147         "generic",
  148         "xen",
  149         NULL
  150 };
  151 
  152 #ifndef XEN
  153 static const char *const vm_bnames[] = {
  154         "QEMU",                         /* QEMU */
  155         "Plex86",                       /* Plex86 */
  156         "Bochs",                        /* Bochs */
  157         "Xen",                          /* Xen */
  158         "Seabios",                      /* KVM */
  159         NULL
  160 };
  161 
  162 static const char *const vm_pnames[] = {
  163         "VMware Virtual Platform",      /* VMWare VM */
  164         "Virtual Machine",              /* Microsoft VirtualPC */
  165         "VirtualBox",                   /* Sun xVM VirtualBox */
  166         "Parallels Virtual Platform",   /* Parallels VM */
  167         "KVM",                          /* KVM */
  168         NULL
  169 };
  170 
  171 
  172 /*
  173  * Detect known Virtual Machine hosts by inspecting the emulated BIOS.
  174  */
  175 static enum VM_GUEST
  176 detect_virtual(void)
  177 {
  178         char *sysenv;
  179         int i;
  180 
  181         sysenv = getenv("smbios.bios.vendor");
  182         if (sysenv != NULL) {
  183                 for (i = 0; vm_bnames[i] != NULL; i++)
  184                         if (strcmp(sysenv, vm_bnames[i]) == 0) {
  185                                 freeenv(sysenv);
  186                                 return (VM_GUEST_VM);
  187                         }
  188                 freeenv(sysenv);
  189         }
  190         sysenv = getenv("smbios.system.product");
  191         if (sysenv != NULL) {
  192                 for (i = 0; vm_pnames[i] != NULL; i++)
  193                         if (strcmp(sysenv, vm_pnames[i]) == 0) {
  194                                 freeenv(sysenv);
  195                                 return (VM_GUEST_VM);
  196                         }
  197                 freeenv(sysenv);
  198         }
  199         return (VM_GUEST_NO);
  200 }
  201 #endif
  202 
  203 /*
  204  * Boot time overrides that are not scaled against main memory
  205  */
  206 void
  207 init_param1(void)
  208 {
  209 #ifndef XEN
  210         vm_guest = detect_virtual();
  211 #else
  212         vm_guest = VM_GUEST_XEN;
  213 #endif
  214         hz = -1;
  215         TUNABLE_INT_FETCH("kern.hz", &hz);
  216         if (hz == -1)
  217                 hz = vm_guest > VM_GUEST_NO ? HZ_VM : HZ;
  218         tick = 1000000 / hz;
  219 
  220 #ifdef VM_SWZONE_SIZE_MAX
  221         maxswzone = VM_SWZONE_SIZE_MAX;
  222 #endif
  223         TUNABLE_LONG_FETCH("kern.maxswzone", &maxswzone);
  224 #ifdef VM_BCACHE_SIZE_MAX
  225         maxbcache = VM_BCACHE_SIZE_MAX;
  226 #endif
  227         TUNABLE_LONG_FETCH("kern.maxbcache", &maxbcache);
  228         msgbufsize = MSGBUF_SIZE;
  229         TUNABLE_INT_FETCH("kern.msgbufsize", &msgbufsize);
  230 
  231         maxtsiz = MAXTSIZ;
  232         TUNABLE_ULONG_FETCH("kern.maxtsiz", &maxtsiz);
  233         dfldsiz = DFLDSIZ;
  234         TUNABLE_ULONG_FETCH("kern.dfldsiz", &dfldsiz);
  235         maxdsiz = MAXDSIZ;
  236         TUNABLE_ULONG_FETCH("kern.maxdsiz", &maxdsiz);
  237         dflssiz = DFLSSIZ;
  238         TUNABLE_ULONG_FETCH("kern.dflssiz", &dflssiz);
  239         maxssiz = MAXSSIZ;
  240         TUNABLE_ULONG_FETCH("kern.maxssiz", &maxssiz);
  241         sgrowsiz = SGROWSIZ;
  242         TUNABLE_ULONG_FETCH("kern.sgrowsiz", &sgrowsiz);
  243 
  244         /*
  245          * Let the administrator set {NGROUPS_MAX}, but disallow values
  246          * less than NGROUPS_MAX which would violate POSIX.1-2008 or
  247          * greater than INT_MAX-1 which would result in overflow.
  248          */
  249         ngroups_max = NGROUPS_MAX;
  250         TUNABLE_INT_FETCH("kern.ngroups", &ngroups_max);
  251         if (ngroups_max < NGROUPS_MAX)
  252                 ngroups_max = NGROUPS_MAX;
  253 }
  254 
  255 /*
  256  * Boot time overrides that are scaled against main memory
  257  */
  258 void
  259 init_param2(long physpages)
  260 {
  261 
  262         /* Base parameters */
  263         maxusers = MAXUSERS;
  264         TUNABLE_INT_FETCH("kern.maxusers", &maxusers);
  265         if (maxusers == 0) {
  266                 maxusers = physpages / (2 * 1024 * 1024 / PAGE_SIZE);
  267                 if (maxusers < 32)
  268                         maxusers = 32;
  269                 if (maxusers > 384)
  270                         maxusers = 384;
  271         }
  272 
  273         /*
  274          * The following can be overridden after boot via sysctl.  Note:
  275          * unless overriden, these macros are ultimately based on maxusers.
  276          */
  277         maxproc = NPROC;
  278         TUNABLE_INT_FETCH("kern.maxproc", &maxproc);
  279         /*
  280          * Limit maxproc so that kmap entries cannot be exhausted by
  281          * processes.
  282          */
  283         if (maxproc > (physpages / 12))
  284                 maxproc = physpages / 12;
  285         maxfiles = MAXFILES;
  286         TUNABLE_INT_FETCH("kern.maxfiles", &maxfiles);
  287         maxprocperuid = (maxproc * 9) / 10;
  288         maxfilesperproc = (maxfiles * 9) / 10;
  289         
  290         /*
  291          * Cannot be changed after boot.
  292          */
  293         nbuf = NBUF;
  294         TUNABLE_INT_FETCH("kern.nbuf", &nbuf);
  295 
  296         ncallout = 16 + maxproc + maxfiles;
  297         TUNABLE_INT_FETCH("kern.ncallout", &ncallout);
  298 }
  299 
  300 /*
  301  * Boot time overrides that are scaled against the kmem map
  302  */
  303 void
  304 init_param3(long kmempages)
  305 {
  306 
  307         /*
  308          * The default for maxpipekva is max(5% of the kmem map, 512KB).
  309          * See sys_pipe.c for more details.
  310          */
  311         maxpipekva = (kmempages / 20) * PAGE_SIZE;
  312         if (maxpipekva < 512 * 1024)
  313                 maxpipekva = 512 * 1024;
  314         TUNABLE_LONG_FETCH("kern.ipc.maxpipekva", &maxpipekva);
  315 }
  316 
  317 /*
  318  * Sysctl stringiying handler for kern.vm_guest.
  319  */
  320 static int
  321 sysctl_kern_vm_guest(SYSCTL_HANDLER_ARGS)
  322 {
  323         return (SYSCTL_OUT(req, vm_guest_sysctl_names[vm_guest], 
  324             strlen(vm_guest_sysctl_names[vm_guest])));
  325 }

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