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("$FreeBSD$");
41
42 #include "opt_param.h"
43 #include "opt_msgbuf.h"
44 #include "opt_maxphys.h"
45 #include "opt_maxusers.h"
46
47 #include <sys/param.h>
48 #include <sys/systm.h>
49 #include <sys/buf.h>
50 #include <sys/kernel.h>
51 #include <sys/limits.h>
52 #include <sys/msgbuf.h>
53 #include <sys/sysctl.h>
54 #include <sys/proc.h>
55 #include <sys/vnode.h>
56
57 #include <vm/vm.h>
58 #include <vm/vm_param.h>
59 #include <vm/pmap.h>
60
61 /*
62 * System parameter formulae.
63 */
64
65 #ifndef HZ
66 # if defined(__mips__) || defined(__arm__)
67 # define HZ 100
68 # else
69 # define HZ 1000
70 # endif
71 # ifndef HZ_VM
72 # define HZ_VM 100
73 # endif
74 #else
75 # ifndef HZ_VM
76 # define HZ_VM HZ
77 # endif
78 #endif
79 #define NPROC (20 + 16 * maxusers)
80 #ifndef NBUF
81 #define NBUF 0
82 #endif
83 #ifndef MAXFILES
84 #define MAXFILES (40 + 32 * maxusers)
85 #endif
86
87 static int sysctl_kern_vm_guest(SYSCTL_HANDLER_ARGS);
88
89 int hz; /* system clock's frequency */
90 int tick; /* usec per tick (1000000 / hz) */
91 struct bintime tick_bt; /* bintime per tick (1s / hz) */
92 sbintime_t tick_sbt;
93 int maxusers; /* base tunable */
94 int maxproc; /* maximum # of processes */
95 int maxprocperuid; /* max # of procs per user */
96 int maxfiles; /* sys. wide open files limit */
97 int maxfilesperproc; /* per-proc open files limit */
98 int msgbufsize; /* size of kernel message buffer */
99 int nbuf; /* number of bcache bufs */
100 int bio_transient_maxcnt;
101 int ngroups_max; /* max # groups per process */
102 int nswbuf;
103 pid_t pid_max = PID_MAX;
104 u_long maxswzone; /* max swmeta KVA storage */
105 u_long maxbcache; /* max buffer cache KVA storage */
106 u_long maxpipekva; /* Limit on pipe KVA */
107 u_long maxphys; /* max raw I/O transfer size */
108 int vm_guest = VM_GUEST_NO; /* Running as virtual machine guest? */
109 u_long maxtsiz; /* max text size */
110 u_long dfldsiz; /* initial data size limit */
111 u_long maxdsiz; /* max data size */
112 u_long dflssiz; /* initial stack size limit */
113 u_long maxssiz; /* max stack size */
114 u_long sgrowsiz; /* amount to grow stack */
115
116 SYSCTL_INT(_kern, OID_AUTO, hz, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &hz, 0,
117 "Number of clock ticks per second");
118 SYSCTL_INT(_kern, OID_AUTO, nbuf, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &nbuf, 0,
119 "Number of buffers in the buffer cache");
120 SYSCTL_INT(_kern, OID_AUTO, nswbuf, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &nswbuf, 0,
121 "Number of swap buffers");
122 SYSCTL_INT(_kern, OID_AUTO, msgbufsize, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &msgbufsize, 0,
123 "Size of the kernel message buffer");
124 SYSCTL_LONG(_kern, OID_AUTO, maxswzone, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &maxswzone, 0,
125 "Maximum memory for swap metadata");
126 SYSCTL_LONG(_kern, OID_AUTO, maxbcache, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &maxbcache, 0,
127 "Maximum value of vfs.maxbufspace");
128 SYSCTL_INT(_kern, OID_AUTO, bio_transient_maxcnt, CTLFLAG_RDTUN | CTLFLAG_NOFETCH,
129 &bio_transient_maxcnt, 0,
130 "Maximum number of transient BIOs mappings");
131 SYSCTL_ULONG(_kern, OID_AUTO, maxtsiz, CTLFLAG_RWTUN | CTLFLAG_NOFETCH, &maxtsiz, 0,
132 "Maximum text size");
133 SYSCTL_ULONG(_kern, OID_AUTO, dfldsiz, CTLFLAG_RWTUN | CTLFLAG_NOFETCH, &dfldsiz, 0,
134 "Initial data size limit");
135 SYSCTL_ULONG(_kern, OID_AUTO, maxdsiz, CTLFLAG_RWTUN | CTLFLAG_NOFETCH, &maxdsiz, 0,
136 "Maximum data size");
137 SYSCTL_ULONG(_kern, OID_AUTO, dflssiz, CTLFLAG_RWTUN | CTLFLAG_NOFETCH, &dflssiz, 0,
138 "Initial stack size limit");
139 SYSCTL_ULONG(_kern, OID_AUTO, maxssiz, CTLFLAG_RWTUN | CTLFLAG_NOFETCH, &maxssiz, 0,
140 "Maximum stack size");
141 SYSCTL_ULONG(_kern, OID_AUTO, sgrowsiz, CTLFLAG_RWTUN | CTLFLAG_NOFETCH, &sgrowsiz, 0,
142 "Amount to grow stack on a stack fault");
143 SYSCTL_PROC(_kern, OID_AUTO, vm_guest,
144 CTLFLAG_RD | CTLTYPE_STRING | CTLFLAG_MPSAFE, NULL, 0,
145 sysctl_kern_vm_guest, "A",
146 "Virtual machine guest detected?");
147
148 /*
149 * The elements of this array are ordered based upon the values of the
150 * corresponding enum VM_GUEST members.
151 */
152 static const char *const vm_guest_sysctl_names[] = {
153 [VM_GUEST_NO] = "none",
154 [VM_GUEST_VM] = "generic",
155 [VM_GUEST_XEN] = "xen",
156 [VM_GUEST_HV] = "hv",
157 [VM_GUEST_VMWARE] = "vmware",
158 [VM_GUEST_KVM] = "kvm",
159 [VM_GUEST_BHYVE] = "bhyve",
160 [VM_GUEST_VBOX] = "vbox",
161 [VM_GUEST_PARALLELS] = "parallels",
162 [VM_LAST] = NULL
163 };
164 CTASSERT(nitems(vm_guest_sysctl_names) - 1 == VM_LAST);
165
166 /*
167 * Boot time overrides that are not scaled against main memory
168 */
169 void
170 init_param1(void)
171 {
172
173 #if !defined(__mips__) && !defined(__arm64__)
174 TUNABLE_INT_FETCH("kern.kstack_pages", &kstack_pages);
175 #endif
176 hz = -1;
177 TUNABLE_INT_FETCH("kern.hz", &hz);
178 if (hz == -1)
179 hz = vm_guest > VM_GUEST_NO ? HZ_VM : HZ;
180 tick = 1000000 / hz;
181 tick_sbt = SBT_1S / hz;
182 tick_bt = sbttobt(tick_sbt);
183
184 /*
185 * Arrange for ticks to wrap 10 minutes after boot to help catch
186 * sign problems sooner.
187 */
188 ticks = INT_MAX - (hz * 10 * 60);
189
190 vn_lock_pair_pause_max = hz / 100;
191 if (vn_lock_pair_pause_max == 0)
192 vn_lock_pair_pause_max = 1;
193
194 #ifdef VM_SWZONE_SIZE_MAX
195 maxswzone = VM_SWZONE_SIZE_MAX;
196 #endif
197 TUNABLE_LONG_FETCH("kern.maxswzone", &maxswzone);
198 #ifdef VM_BCACHE_SIZE_MAX
199 maxbcache = VM_BCACHE_SIZE_MAX;
200 #endif
201 TUNABLE_LONG_FETCH("kern.maxbcache", &maxbcache);
202 msgbufsize = MSGBUF_SIZE;
203 TUNABLE_INT_FETCH("kern.msgbufsize", &msgbufsize);
204
205 maxtsiz = MAXTSIZ;
206 TUNABLE_ULONG_FETCH("kern.maxtsiz", &maxtsiz);
207 dfldsiz = DFLDSIZ;
208 TUNABLE_ULONG_FETCH("kern.dfldsiz", &dfldsiz);
209 maxdsiz = MAXDSIZ;
210 TUNABLE_ULONG_FETCH("kern.maxdsiz", &maxdsiz);
211 dflssiz = DFLSSIZ;
212 TUNABLE_ULONG_FETCH("kern.dflssiz", &dflssiz);
213 maxssiz = MAXSSIZ;
214 TUNABLE_ULONG_FETCH("kern.maxssiz", &maxssiz);
215 sgrowsiz = SGROWSIZ;
216 TUNABLE_ULONG_FETCH("kern.sgrowsiz", &sgrowsiz);
217
218 /*
219 * Let the administrator set {NGROUPS_MAX}, but disallow values
220 * less than NGROUPS_MAX which would violate POSIX.1-2008 or
221 * greater than INT_MAX-1 which would result in overflow.
222 */
223 ngroups_max = NGROUPS_MAX;
224 TUNABLE_INT_FETCH("kern.ngroups", &ngroups_max);
225 if (ngroups_max < NGROUPS_MAX)
226 ngroups_max = NGROUPS_MAX;
227
228 /*
229 * Only allow to lower the maximal pid.
230 * Prevent setting up a non-bootable system if pid_max is too low.
231 */
232 TUNABLE_INT_FETCH("kern.pid_max", &pid_max);
233 if (pid_max > PID_MAX)
234 pid_max = PID_MAX;
235 else if (pid_max < 300)
236 pid_max = 300;
237
238 TUNABLE_INT_FETCH("vfs.unmapped_buf_allowed", &unmapped_buf_allowed);
239 }
240
241 /*
242 * Boot time overrides that are scaled against main memory
243 */
244 void
245 init_param2(long physpages)
246 {
247
248 /* Base parameters */
249 maxusers = MAXUSERS;
250 TUNABLE_INT_FETCH("kern.maxusers", &maxusers);
251 if (maxusers == 0) {
252 maxusers = physpages / (2 * 1024 * 1024 / PAGE_SIZE);
253 if (maxusers < 32)
254 maxusers = 32;
255 #ifdef VM_MAX_AUTOTUNE_MAXUSERS
256 if (maxusers > VM_MAX_AUTOTUNE_MAXUSERS)
257 maxusers = VM_MAX_AUTOTUNE_MAXUSERS;
258 #endif
259 /*
260 * Scales down the function in which maxusers grows once
261 * we hit 384.
262 */
263 if (maxusers > 384)
264 maxusers = 384 + ((maxusers - 384) / 8);
265 }
266
267 /*
268 * The following can be overridden after boot via sysctl. Note:
269 * unless overriden, these macros are ultimately based on maxusers.
270 * Limit maxproc so that kmap entries cannot be exhausted by
271 * processes.
272 */
273 maxproc = NPROC;
274 TUNABLE_INT_FETCH("kern.maxproc", &maxproc);
275 if (maxproc > (physpages / 12))
276 maxproc = physpages / 12;
277 if (maxproc > pid_max)
278 maxproc = pid_max;
279 maxprocperuid = (maxproc * 9) / 10;
280
281 /*
282 * The default limit for maxfiles is 1/12 of the number of
283 * physical page but not less than 16 times maxusers.
284 * At most it can be 1/6 the number of physical pages.
285 */
286 maxfiles = imax(MAXFILES, physpages / 8);
287 TUNABLE_INT_FETCH("kern.maxfiles", &maxfiles);
288 if (maxfiles > (physpages / 4))
289 maxfiles = physpages / 4;
290 maxfilesperproc = (maxfiles / 10) * 9;
291 TUNABLE_INT_FETCH("kern.maxfilesperproc", &maxfilesperproc);
292
293 /*
294 * Cannot be changed after boot.
295 */
296 nbuf = NBUF;
297 TUNABLE_INT_FETCH("kern.nbuf", &nbuf);
298 TUNABLE_INT_FETCH("kern.bio_transient_maxcnt", &bio_transient_maxcnt);
299 maxphys = MAXPHYS;
300 TUNABLE_ULONG_FETCH("kern.maxphys", &maxphys);
301 if (maxphys == 0) {
302 maxphys = MAXPHYS;
303 } else if (__bitcountl(maxphys) != 1) { /* power of two */
304 if (flsl(maxphys) == NBBY * sizeof(maxphys))
305 maxphys = MAXPHYS;
306 else
307 maxphys = 1UL << flsl(maxphys);
308 }
309 if (maxphys < PAGE_SIZE)
310 maxphys = MAXPHYS;
311
312 /*
313 * Physical buffers are pre-allocated buffers (struct buf) that
314 * are used as temporary holders for I/O, such as paging I/O.
315 */
316 TUNABLE_INT_FETCH("kern.nswbuf", &nswbuf);
317
318 /*
319 * The default for maxpipekva is min(1/64 of the kernel address space,
320 * max(1/64 of main memory, 512KB)). See sys_pipe.c for more details.
321 */
322 maxpipekva = ptoa(physpages / 64);
323 TUNABLE_LONG_FETCH("kern.ipc.maxpipekva", &maxpipekva);
324 if (maxpipekva < 512 * 1024)
325 maxpipekva = 512 * 1024;
326 if (maxpipekva > (VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS) / 64)
327 maxpipekva = (VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS) /
328 64;
329 }
330
331 /*
332 * Sysctl stringifying handler for kern.vm_guest.
333 */
334 static int
335 sysctl_kern_vm_guest(SYSCTL_HANDLER_ARGS)
336 {
337 return (SYSCTL_OUT_STR(req, vm_guest_sysctl_names[vm_guest]));
338 }
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