FreeBSD/Linux Kernel Cross Reference
sys/kern/subr_param.c
1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1980, 1986, 1989, 1993
5 * The Regents of the University of California. All rights reserved.
6 * (c) UNIX System Laboratories, Inc.
7 * All or some portions of this file are derived from material licensed
8 * to the University of California by American Telephone and Telegraph
9 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
10 * the permission of UNIX System Laboratories, Inc.
11 *
12 * Redistribution and use in source and binary forms, with or without
13 * modification, are permitted provided that the following conditions
14 * are met:
15 * 1. Redistributions of source code must retain the above copyright
16 * notice, this list of conditions and the following disclaimer.
17 * 2. Redistributions in binary form must reproduce the above copyright
18 * notice, this list of conditions and the following disclaimer in the
19 * documentation and/or other materials provided with the distribution.
20 * 3. Neither the name of the University nor the names of its contributors
21 * may be used to endorse or promote products derived from this software
22 * without specific prior written permission.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 * SUCH DAMAGE.
35 *
36 * @(#)param.c 8.3 (Berkeley) 8/20/94
37 */
38
39 #include <sys/cdefs.h>
40 __FBSDID("$FreeBSD: releng/12.0/sys/kern/subr_param.c 326023 2017-11-20 19:43:44Z pfg $");
41
42 #include "opt_param.h"
43 #include "opt_msgbuf.h"
44 #include "opt_maxusers.h"
45
46 #include <sys/param.h>
47 #include <sys/systm.h>
48 #include <sys/kernel.h>
49 #include <sys/limits.h>
50 #include <sys/msgbuf.h>
51 #include <sys/sysctl.h>
52 #include <sys/proc.h>
53
54 #include <vm/vm.h>
55 #include <vm/vm_param.h>
56 #include <vm/pmap.h>
57
58 /*
59 * System parameter formulae.
60 */
61
62 #ifndef HZ
63 # if defined(__mips__) || defined(__arm__)
64 # define HZ 100
65 # else
66 # define HZ 1000
67 # endif
68 # ifndef HZ_VM
69 # define HZ_VM 100
70 # endif
71 #else
72 # ifndef HZ_VM
73 # define HZ_VM HZ
74 # endif
75 #endif
76 #define NPROC (20 + 16 * maxusers)
77 #ifndef NBUF
78 #define NBUF 0
79 #endif
80 #ifndef MAXFILES
81 #define MAXFILES (40 + 32 * maxusers)
82 #endif
83
84 static int sysctl_kern_vm_guest(SYSCTL_HANDLER_ARGS);
85
86 int hz; /* system clock's frequency */
87 int tick; /* usec per tick (1000000 / hz) */
88 struct bintime tick_bt; /* bintime per tick (1s / hz) */
89 sbintime_t tick_sbt;
90 int maxusers; /* base tunable */
91 int maxproc; /* maximum # of processes */
92 int maxprocperuid; /* max # of procs per user */
93 int maxfiles; /* sys. wide open files limit */
94 int maxfilesperproc; /* per-proc open files limit */
95 int msgbufsize; /* size of kernel message buffer */
96 int nbuf;
97 int bio_transient_maxcnt;
98 int ngroups_max; /* max # groups per process */
99 int nswbuf;
100 pid_t pid_max = PID_MAX;
101 long maxswzone; /* max swmeta KVA storage */
102 long maxbcache; /* max buffer cache KVA storage */
103 long maxpipekva; /* Limit on pipe KVA */
104 int vm_guest = VM_GUEST_NO; /* Running as virtual machine guest? */
105 u_long maxtsiz; /* max text size */
106 u_long dfldsiz; /* initial data size limit */
107 u_long maxdsiz; /* max data size */
108 u_long dflssiz; /* initial stack size limit */
109 u_long maxssiz; /* max stack size */
110 u_long sgrowsiz; /* amount to grow stack */
111
112 SYSCTL_INT(_kern, OID_AUTO, hz, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &hz, 0,
113 "Number of clock ticks per second");
114 SYSCTL_INT(_kern, OID_AUTO, nbuf, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &nbuf, 0,
115 "Number of buffers in the buffer cache");
116 SYSCTL_INT(_kern, OID_AUTO, nswbuf, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &nswbuf, 0,
117 "Number of swap buffers");
118 SYSCTL_INT(_kern, OID_AUTO, msgbufsize, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &msgbufsize, 0,
119 "Size of the kernel message buffer");
120 SYSCTL_LONG(_kern, OID_AUTO, maxswzone, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &maxswzone, 0,
121 "Maximum memory for swap metadata");
122 SYSCTL_LONG(_kern, OID_AUTO, maxbcache, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &maxbcache, 0,
123 "Maximum value of vfs.maxbufspace");
124 SYSCTL_INT(_kern, OID_AUTO, bio_transient_maxcnt, CTLFLAG_RDTUN | CTLFLAG_NOFETCH,
125 &bio_transient_maxcnt, 0,
126 "Maximum number of transient BIOs mappings");
127 SYSCTL_ULONG(_kern, OID_AUTO, maxtsiz, CTLFLAG_RWTUN | CTLFLAG_NOFETCH, &maxtsiz, 0,
128 "Maximum text size");
129 SYSCTL_ULONG(_kern, OID_AUTO, dfldsiz, CTLFLAG_RWTUN | CTLFLAG_NOFETCH, &dfldsiz, 0,
130 "Initial data size limit");
131 SYSCTL_ULONG(_kern, OID_AUTO, maxdsiz, CTLFLAG_RWTUN | CTLFLAG_NOFETCH, &maxdsiz, 0,
132 "Maximum data size");
133 SYSCTL_ULONG(_kern, OID_AUTO, dflssiz, CTLFLAG_RWTUN | CTLFLAG_NOFETCH, &dflssiz, 0,
134 "Initial stack size limit");
135 SYSCTL_ULONG(_kern, OID_AUTO, maxssiz, CTLFLAG_RWTUN | CTLFLAG_NOFETCH, &maxssiz, 0,
136 "Maximum stack size");
137 SYSCTL_ULONG(_kern, OID_AUTO, sgrowsiz, CTLFLAG_RWTUN | CTLFLAG_NOFETCH, &sgrowsiz, 0,
138 "Amount to grow stack on a stack fault");
139 SYSCTL_PROC(_kern, OID_AUTO, vm_guest, CTLFLAG_RD | CTLTYPE_STRING,
140 NULL, 0, sysctl_kern_vm_guest, "A",
141 "Virtual machine guest detected?");
142
143 /*
144 * The elements of this array are ordered based upon the values of the
145 * corresponding enum VM_GUEST members.
146 */
147 static const char *const vm_guest_sysctl_names[] = {
148 "none",
149 "generic",
150 "xen",
151 "hv",
152 "vmware",
153 "kvm",
154 "bhyve",
155 NULL
156 };
157 CTASSERT(nitems(vm_guest_sysctl_names) - 1 == VM_LAST);
158
159 /*
160 * Boot time overrides that are not scaled against main memory
161 */
162 void
163 init_param1(void)
164 {
165
166 #if !defined(__mips__) && !defined(__arm64__) && !defined(__sparc64__)
167 TUNABLE_INT_FETCH("kern.kstack_pages", &kstack_pages);
168 #endif
169 hz = -1;
170 TUNABLE_INT_FETCH("kern.hz", &hz);
171 if (hz == -1)
172 hz = vm_guest > VM_GUEST_NO ? HZ_VM : HZ;
173 tick = 1000000 / hz;
174 tick_sbt = SBT_1S / hz;
175 tick_bt = sbttobt(tick_sbt);
176
177 /*
178 * Arrange for ticks to wrap 10 minutes after boot to help catch
179 * sign problems sooner.
180 */
181 ticks = INT_MAX - (hz * 10 * 60);
182
183 #ifdef VM_SWZONE_SIZE_MAX
184 maxswzone = VM_SWZONE_SIZE_MAX;
185 #endif
186 TUNABLE_LONG_FETCH("kern.maxswzone", &maxswzone);
187 #ifdef VM_BCACHE_SIZE_MAX
188 maxbcache = VM_BCACHE_SIZE_MAX;
189 #endif
190 TUNABLE_LONG_FETCH("kern.maxbcache", &maxbcache);
191 msgbufsize = MSGBUF_SIZE;
192 TUNABLE_INT_FETCH("kern.msgbufsize", &msgbufsize);
193
194 maxtsiz = MAXTSIZ;
195 TUNABLE_ULONG_FETCH("kern.maxtsiz", &maxtsiz);
196 dfldsiz = DFLDSIZ;
197 TUNABLE_ULONG_FETCH("kern.dfldsiz", &dfldsiz);
198 maxdsiz = MAXDSIZ;
199 TUNABLE_ULONG_FETCH("kern.maxdsiz", &maxdsiz);
200 dflssiz = DFLSSIZ;
201 TUNABLE_ULONG_FETCH("kern.dflssiz", &dflssiz);
202 maxssiz = MAXSSIZ;
203 TUNABLE_ULONG_FETCH("kern.maxssiz", &maxssiz);
204 sgrowsiz = SGROWSIZ;
205 TUNABLE_ULONG_FETCH("kern.sgrowsiz", &sgrowsiz);
206
207 /*
208 * Let the administrator set {NGROUPS_MAX}, but disallow values
209 * less than NGROUPS_MAX which would violate POSIX.1-2008 or
210 * greater than INT_MAX-1 which would result in overflow.
211 */
212 ngroups_max = NGROUPS_MAX;
213 TUNABLE_INT_FETCH("kern.ngroups", &ngroups_max);
214 if (ngroups_max < NGROUPS_MAX)
215 ngroups_max = NGROUPS_MAX;
216
217 /*
218 * Only allow to lower the maximal pid.
219 * Prevent setting up a non-bootable system if pid_max is too low.
220 */
221 TUNABLE_INT_FETCH("kern.pid_max", &pid_max);
222 if (pid_max > PID_MAX)
223 pid_max = PID_MAX;
224 else if (pid_max < 300)
225 pid_max = 300;
226
227 TUNABLE_INT_FETCH("vfs.unmapped_buf_allowed", &unmapped_buf_allowed);
228 }
229
230 /*
231 * Boot time overrides that are scaled against main memory
232 */
233 void
234 init_param2(long physpages)
235 {
236
237 /* Base parameters */
238 maxusers = MAXUSERS;
239 TUNABLE_INT_FETCH("kern.maxusers", &maxusers);
240 if (maxusers == 0) {
241 maxusers = physpages / (2 * 1024 * 1024 / PAGE_SIZE);
242 if (maxusers < 32)
243 maxusers = 32;
244 #ifdef VM_MAX_AUTOTUNE_MAXUSERS
245 if (maxusers > VM_MAX_AUTOTUNE_MAXUSERS)
246 maxusers = VM_MAX_AUTOTUNE_MAXUSERS;
247 #endif
248 /*
249 * Scales down the function in which maxusers grows once
250 * we hit 384.
251 */
252 if (maxusers > 384)
253 maxusers = 384 + ((maxusers - 384) / 8);
254 }
255
256 /*
257 * The following can be overridden after boot via sysctl. Note:
258 * unless overriden, these macros are ultimately based on maxusers.
259 * Limit maxproc so that kmap entries cannot be exhausted by
260 * processes.
261 */
262 maxproc = NPROC;
263 TUNABLE_INT_FETCH("kern.maxproc", &maxproc);
264 if (maxproc > (physpages / 12))
265 maxproc = physpages / 12;
266 if (maxproc > pid_max)
267 maxproc = pid_max;
268 maxprocperuid = (maxproc * 9) / 10;
269
270 /*
271 * The default limit for maxfiles is 1/12 of the number of
272 * physical page but not less than 16 times maxusers.
273 * At most it can be 1/6 the number of physical pages.
274 */
275 maxfiles = imax(MAXFILES, physpages / 8);
276 TUNABLE_INT_FETCH("kern.maxfiles", &maxfiles);
277 if (maxfiles > (physpages / 4))
278 maxfiles = physpages / 4;
279 maxfilesperproc = (maxfiles / 10) * 9;
280 TUNABLE_INT_FETCH("kern.maxfilesperproc", &maxfilesperproc);
281
282 /*
283 * Cannot be changed after boot.
284 */
285 nbuf = NBUF;
286 TUNABLE_INT_FETCH("kern.nbuf", &nbuf);
287 TUNABLE_INT_FETCH("kern.bio_transient_maxcnt", &bio_transient_maxcnt);
288
289 /*
290 * The default for maxpipekva is min(1/64 of the kernel address space,
291 * max(1/64 of main memory, 512KB)). See sys_pipe.c for more details.
292 */
293 maxpipekva = (physpages / 64) * PAGE_SIZE;
294 TUNABLE_LONG_FETCH("kern.ipc.maxpipekva", &maxpipekva);
295 if (maxpipekva < 512 * 1024)
296 maxpipekva = 512 * 1024;
297 if (maxpipekva > (VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS) / 64)
298 maxpipekva = (VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS) /
299 64;
300 }
301
302 /*
303 * Sysctl stringifying handler for kern.vm_guest.
304 */
305 static int
306 sysctl_kern_vm_guest(SYSCTL_HANDLER_ARGS)
307 {
308 return (SYSCTL_OUT_STR(req, vm_guest_sysctl_names[vm_guest]));
309 }
Cache object: 30a64d1abf26486506db556cfa2fdba5
|