subr_param.c

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/*-
 * Copyright (c) 1980, 1986, 1989, 1993
 *      The Regents of the University of California.  All rights reserved.
 * (c) UNIX System Laboratories, Inc.
 * All or some portions of this file are derived from material licensed
 * to the University of California by American Telephone and Telegraph
 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
 * the permission of UNIX System Laboratories, Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *      @(#)param.c     8.3 (Berkeley) 8/20/94
 */

#include <sys/cdefs.h>
__FBSDID("$BSDSUniX$");

#include "opt_param.h"
#include "opt_msgbuf.h"
#include "opt_maxusers.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/limits.h>
#include <sys/msgbuf.h>
#include <sys/sysctl.h>
#include <sys/proc.h>

#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/pmap.h>

/*
 * System parameter formulae.
 */

#ifndef HZ
#  if defined(__mips__) || defined(__arm__)
#    define     HZ 100
#  else
#    define     HZ 1000
#  endif
#  ifndef HZ_VM
#    define     HZ_VM 100
#  endif
#else
#  ifndef HZ_VM
#    define     HZ_VM HZ
#  endif
#endif
#define NPROC (20 + 16 * maxusers)
#ifndef NBUF
#define NBUF 0
#endif
#ifndef MAXFILES
#define MAXFILES (maxproc * 2)
#endif

static int sysctl_kern_vm_guest(SYSCTL_HANDLER_ARGS);

int     hz;
int     tick;
int     maxusers;                       /* base tunable */
int     maxproc;                        /* maximum # of processes */
int     maxprocperuid;                  /* max # of procs per user */
int     maxfiles;                       /* sys. wide open files limit */
int     maxfilesperproc;                /* per-proc open files limit */
int     msgbufsize;                     /* size of kernel message buffer */
int     ncallout;                       /* maximum # of timer events */
int     nbuf;
int     bio_transient_maxcnt;
int     ngroups_max;                    /* max # groups per process */
int     nswbuf;
pid_t   pid_max = PID_MAX;
long    maxswzone;                      /* max swmeta KVA storage */
long    maxbcache;                      /* max buffer cache KVA storage */
long    maxpipekva;                     /* Limit on pipe KVA */
int     vm_guest;                       /* Running as virtual machine guest? */
u_long  maxtsiz;                        /* max text size */
u_long  dfldsiz;                        /* initial data size limit */
u_long  maxdsiz;                        /* max data size */
u_long  dflssiz;                        /* initial stack size limit */
u_long  maxssiz;                        /* max stack size */
u_long  sgrowsiz;                       /* amount to grow stack */

SYSCTL_INT(_kern, OID_AUTO, hz, CTLFLAG_RDTUN, &hz, 0,
    "Number of clock ticks per second");
SYSCTL_INT(_kern, OID_AUTO, ncallout, CTLFLAG_RDTUN, &ncallout, 0,
    "Number of pre-allocated timer events");
SYSCTL_INT(_kern, OID_AUTO, nbuf, CTLFLAG_RDTUN, &nbuf, 0,
    "Number of buffers in the buffer cache");
SYSCTL_INT(_kern, OID_AUTO, nswbuf, CTLFLAG_RDTUN, &nswbuf, 0,
    "Number of swap buffers");
SYSCTL_INT(_kern, OID_AUTO, msgbufsize, CTLFLAG_RDTUN, &msgbufsize, 0,
    "Size of the kernel message buffer");
SYSCTL_LONG(_kern, OID_AUTO, maxswzone, CTLFLAG_RDTUN, &maxswzone, 0,
    "Maximum memory for swap metadata");
SYSCTL_LONG(_kern, OID_AUTO, maxbcache, CTLFLAG_RDTUN, &maxbcache, 0,
    "Maximum value of vfs.maxbufspace");
SYSCTL_INT(_kern, OID_AUTO, bio_transient_maxcnt, CTLFLAG_RDTUN,
    &bio_transient_maxcnt, 0,
    "Maximum number of transient BIOs mappings");
SYSCTL_ULONG(_kern, OID_AUTO, maxtsiz, CTLFLAG_RW | CTLFLAG_TUN, &maxtsiz, 0,
    "Maximum text size");
SYSCTL_ULONG(_kern, OID_AUTO, dfldsiz, CTLFLAG_RW | CTLFLAG_TUN, &dfldsiz, 0,
    "Initial data size limit");
SYSCTL_ULONG(_kern, OID_AUTO, maxdsiz, CTLFLAG_RW | CTLFLAG_TUN, &maxdsiz, 0,
    "Maximum data size");
SYSCTL_ULONG(_kern, OID_AUTO, dflssiz, CTLFLAG_RW | CTLFLAG_TUN, &dflssiz, 0,
    "Initial stack size limit");
SYSCTL_ULONG(_kern, OID_AUTO, maxssiz, CTLFLAG_RW | CTLFLAG_TUN, &maxssiz, 0,
    "Maximum stack size");
SYSCTL_ULONG(_kern, OID_AUTO, sgrowsiz, CTLFLAG_RW | CTLFLAG_TUN, &sgrowsiz, 0,
    "Amount to grow stack on a stack fault");
SYSCTL_PROC(_kern, OID_AUTO, vm_guest, CTLFLAG_RD | CTLTYPE_STRING,
    NULL, 0, sysctl_kern_vm_guest, "A",
    "Virtual machine guest detected? (none|generic|xen)");

/*
 * These have to be allocated somewhere; allocating
 * them here forces loader errors if this file is omitted
 * (if they've been externed everywhere else; hah!).
 */
struct  buf *swbuf;

/*
 * The elements of this array are ordered based upon the values of the
 * corresponding enum VM_GUEST members.
 */
static const char *const vm_guest_sysctl_names[] = {
        "none",
        "generic",
        "xen",
        NULL
};

#ifndef XEN
static const char *const vm_bnames[] = {
        "QEMU",                         /* QEMU */
        "Plex86",                       /* Plex86 */
        "Bochs",                        /* Bochs */
        "Xen",                          /* Xen */
        "BHYVE",                        /* bhyve */
        "Seabios",                      /* KVM */
        NULL
};

static const char *const vm_pnames[] = {
        "VMware Virtual Platform",      /* VMWare VM */
        "Virtual Machine",              /* Microsoft VirtualPC */
        "VirtualBox",                   /* Sun xVM VirtualBox */
        "Parallels Virtual Platform",   /* Parallels VM */
        "KVM",                          /* KVM */
        NULL
};


/*
 * Detect known Virtual Machine hosts by inspecting the emulated BIOS.
 */
static enum VM_GUEST
detect_virtual(void)
{
        char *sysenv;
        int i;

        sysenv = getenv("smbios.bios.vendor");
        if (sysenv != NULL) {
                for (i = 0; vm_bnames[i] != NULL; i++)
                        if (strcmp(sysenv, vm_bnames[i]) == 0) {
                                freeenv(sysenv);
                                return (VM_GUEST_VM);
                        }
                freeenv(sysenv);
        }
        sysenv = getenv("smbios.system.product");
        if (sysenv != NULL) {
                for (i = 0; vm_pnames[i] != NULL; i++)
                        if (strcmp(sysenv, vm_pnames[i]) == 0) {
                                freeenv(sysenv);
                                return (VM_GUEST_VM);
                        }
                freeenv(sysenv);
        }
        return (VM_GUEST_NO);
}
#endif

/*
 * Boot time overrides that are not scaled against main memory
 */
void
init_param1(void)
{
#ifndef XEN
        vm_guest = detect_virtual();
#else
        vm_guest = VM_GUEST_XEN;
#endif
        hz = -1;
        TUNABLE_INT_FETCH("kern.hz", &hz);
        if (hz == -1)
                hz = vm_guest > VM_GUEST_NO ? HZ_VM : HZ;
        tick = 1000000 / hz;

#ifdef VM_SWZONE_SIZE_MAX
        maxswzone = VM_SWZONE_SIZE_MAX;
#endif
        TUNABLE_LONG_FETCH("kern.maxswzone", &maxswzone);
#ifdef VM_BCACHE_SIZE_MAX
        maxbcache = VM_BCACHE_SIZE_MAX;
#endif
        TUNABLE_LONG_FETCH("kern.maxbcache", &maxbcache);
        msgbufsize = MSGBUF_SIZE;
        TUNABLE_INT_FETCH("kern.msgbufsize", &msgbufsize);

        maxtsiz = MAXTSIZ;
        TUNABLE_ULONG_FETCH("kern.maxtsiz", &maxtsiz);
        dfldsiz = DFLDSIZ;
        TUNABLE_ULONG_FETCH("kern.dfldsiz", &dfldsiz);
        maxdsiz = MAXDSIZ;
        TUNABLE_ULONG_FETCH("kern.maxdsiz", &maxdsiz);
        dflssiz = DFLSSIZ;
        TUNABLE_ULONG_FETCH("kern.dflssiz", &dflssiz);
        maxssiz = MAXSSIZ;
        TUNABLE_ULONG_FETCH("kern.maxssiz", &maxssiz);
        sgrowsiz = SGROWSIZ;
        TUNABLE_ULONG_FETCH("kern.sgrowsiz", &sgrowsiz);

        /*
         * Let the administrator set {NGROUPS_MAX}, but disallow values
         * less than NGROUPS_MAX which would violate POSIX.1-2008 or
         * greater than INT_MAX-1 which would result in overflow.
         */
        ngroups_max = NGROUPS_MAX;
        TUNABLE_INT_FETCH("kern.ngroups", &ngroups_max);
        if (ngroups_max < NGROUPS_MAX)
                ngroups_max = NGROUPS_MAX;

        /*
         * Only allow to lower the maximal pid.
         * Prevent setting up a non-bootable system if pid_max is too low.
         */
        TUNABLE_INT_FETCH("kern.pid_max", &pid_max);
        if (pid_max > PID_MAX)
                pid_max = PID_MAX;
        else if (pid_max < 300)
                pid_max = 300;

        TUNABLE_INT_FETCH("vfs.unmapped_buf_allowed", &unmapped_buf_allowed);
}

/*
 * Boot time overrides that are scaled against main memory
 */
void
init_param2(long physpages)
{

        /* Base parameters */
        maxusers = MAXUSERS;
        TUNABLE_INT_FETCH("kern.maxusers", &maxusers);
        if (maxusers == 0) {
                maxusers = physpages / (2 * 1024 * 1024 / PAGE_SIZE);
                if (maxusers < 32)
                        maxusers = 32;
#ifdef VM_MAX_AUTOTUNE_MAXUSERS
                if (maxusers > VM_MAX_AUTOTUNE_MAXUSERS)
                        maxusers = VM_MAX_AUTOTUNE_MAXUSERS;
#endif
                /*
                 * Scales down the function in which maxusers grows once
                 * we hit 384.
                 */
                if (maxusers > 384)
                        maxusers = 384 + ((maxusers - 384) / 8);
        }

        /*
         * The following can be overridden after boot via sysctl.  Note:
         * unless overriden, these macros are ultimately based on maxusers.
         * Limit maxproc so that kmap entries cannot be exhausted by
         * processes.
         */
        maxproc = NPROC;
        TUNABLE_INT_FETCH("kern.maxproc", &maxproc);
        if (maxproc > (physpages / 12))
                maxproc = physpages / 12;
        maxprocperuid = (maxproc * 9) / 10;

        /*
         * The default limit for maxfiles is 1/12 of the number of
         * physical page but not less than 16 times maxusers.
         * At most it can be 1/6 the number of physical pages.
         */
        maxfiles = imax(MAXFILES, physpages / 8);
        TUNABLE_INT_FETCH("kern.maxfiles", &maxfiles);
        if (maxfiles > (physpages / 4))
                maxfiles = physpages / 4;
        maxfilesperproc = (maxfiles / 10) * 9;
        
        /*
         * Cannot be changed after boot.
         */
        nbuf = NBUF;
        TUNABLE_INT_FETCH("kern.nbuf", &nbuf);
        TUNABLE_INT_FETCH("kern.bio_transient_maxcnt", &bio_transient_maxcnt);

        /*
         * XXX: Does the callout wheel have to be so big?
         *
         * Clip callout to result of previous function of maxusers maximum
         * 384.  This is still huge, but acceptable.
         */
        ncallout = imin(16 + maxproc + maxfiles, 18508);
        TUNABLE_INT_FETCH("kern.ncallout", &ncallout);

        /*
         * The default for maxpipekva is min(1/64 of the kernel address space,
         * max(1/64 of main memory, 512KB)).  See sys_pipe.c for more details.
         */
        maxpipekva = (physpages / 64) * PAGE_SIZE;
        TUNABLE_LONG_FETCH("kern.ipc.maxpipekva", &maxpipekva);
        if (maxpipekva < 512 * 1024)
                maxpipekva = 512 * 1024;
        if (maxpipekva > (VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS) / 64)
                maxpipekva = (VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS) /
                    64;
}

/*
 * Sysctl stringifying handler for kern.vm_guest.
 */
static int
sysctl_kern_vm_guest(SYSCTL_HANDLER_ARGS)
{
        return (SYSCTL_OUT(req, vm_guest_sysctl_names[vm_guest], 
            strlen(vm_guest_sysctl_names[vm_guest])));
}