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34 * @(#)param.c 8.3 (Berkeley) 8/20/94
37 #include <sys/cdefs.h>
38 __FBSDID("$FreeBSD$");
40 #include "opt_param.h"
41 #include "opt_msgbuf.h"
42 #include "opt_maxusers.h"
44 #include <sys/param.h>
45 #include <sys/systm.h>
46 #include <sys/kernel.h>
47 #include <sys/limits.h>
48 #include <sys/msgbuf.h>
49 #include <sys/sysctl.h>
53 #include <vm/vm_param.h>
57 * System parameter formulae.
61 # if defined(__mips__) || defined(__arm__)
74 #define NPROC (20 + 16 * maxusers)
79 #define MAXFILES (40 + 32 * maxusers)
82 static int sysctl_kern_vm_guest(SYSCTL_HANDLER_ARGS);
84 int hz; /* system clock's frequency */
85 int tick; /* usec per tick (1000000 / hz) */
86 struct bintime tick_bt; /* bintime per tick (1s / hz) */
88 int maxusers; /* base tunable */
89 int maxproc; /* maximum # of processes */
90 int maxprocperuid; /* max # of procs per user */
91 int maxfiles; /* sys. wide open files limit */
92 int maxfilesperproc; /* per-proc open files limit */
93 int msgbufsize; /* size of kernel message buffer */
95 int bio_transient_maxcnt;
96 int ngroups_max; /* max # groups per process */
98 pid_t pid_max = PID_MAX;
99 long maxswzone; /* max swmeta KVA storage */
100 long maxbcache; /* max buffer cache KVA storage */
101 long maxpipekva; /* Limit on pipe KVA */
102 int vm_guest = VM_GUEST_NO; /* Running as virtual machine guest? */
103 u_long maxtsiz; /* max text size */
104 u_long dfldsiz; /* initial data size limit */
105 u_long maxdsiz; /* max data size */
106 u_long dflssiz; /* initial stack size limit */
107 u_long maxssiz; /* max stack size */
108 u_long sgrowsiz; /* amount to grow stack */
110 SYSCTL_INT(_kern, OID_AUTO, hz, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &hz, 0,
111 "Number of clock ticks per second");
112 SYSCTL_INT(_kern, OID_AUTO, nbuf, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &nbuf, 0,
113 "Number of buffers in the buffer cache");
114 SYSCTL_INT(_kern, OID_AUTO, nswbuf, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &nswbuf, 0,
115 "Number of swap buffers");
116 SYSCTL_INT(_kern, OID_AUTO, msgbufsize, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &msgbufsize, 0,
117 "Size of the kernel message buffer");
118 SYSCTL_LONG(_kern, OID_AUTO, maxswzone, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &maxswzone, 0,
119 "Maximum memory for swap metadata");
120 SYSCTL_LONG(_kern, OID_AUTO, maxbcache, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &maxbcache, 0,
121 "Maximum value of vfs.maxbufspace");
122 SYSCTL_INT(_kern, OID_AUTO, bio_transient_maxcnt, CTLFLAG_RDTUN | CTLFLAG_NOFETCH,
123 &bio_transient_maxcnt, 0,
124 "Maximum number of transient BIOs mappings");
125 SYSCTL_ULONG(_kern, OID_AUTO, maxtsiz, CTLFLAG_RWTUN | CTLFLAG_NOFETCH, &maxtsiz, 0,
126 "Maximum text size");
127 SYSCTL_ULONG(_kern, OID_AUTO, dfldsiz, CTLFLAG_RWTUN | CTLFLAG_NOFETCH, &dfldsiz, 0,
128 "Initial data size limit");
129 SYSCTL_ULONG(_kern, OID_AUTO, maxdsiz, CTLFLAG_RWTUN | CTLFLAG_NOFETCH, &maxdsiz, 0,
130 "Maximum data size");
131 SYSCTL_ULONG(_kern, OID_AUTO, dflssiz, CTLFLAG_RWTUN | CTLFLAG_NOFETCH, &dflssiz, 0,
132 "Initial stack size limit");
133 SYSCTL_ULONG(_kern, OID_AUTO, maxssiz, CTLFLAG_RWTUN | CTLFLAG_NOFETCH, &maxssiz, 0,
134 "Maximum stack size");
135 SYSCTL_ULONG(_kern, OID_AUTO, sgrowsiz, CTLFLAG_RWTUN | CTLFLAG_NOFETCH, &sgrowsiz, 0,
136 "Amount to grow stack on a stack fault");
137 SYSCTL_PROC(_kern, OID_AUTO, vm_guest, CTLFLAG_RD | CTLTYPE_STRING,
138 NULL, 0, sysctl_kern_vm_guest, "A",
139 "Virtual machine guest detected?");
142 * The elements of this array are ordered based upon the values of the
143 * corresponding enum VM_GUEST members.
145 static const char *const vm_guest_sysctl_names[] = {
155 CTASSERT(nitems(vm_guest_sysctl_names) - 1 == VM_LAST);
158 * Boot time overrides that are not scaled against main memory
164 #if !defined(__mips__) && !defined(__arm64__) && !defined(__sparc64__)
165 TUNABLE_INT_FETCH("kern.kstack_pages", &kstack_pages);
168 TUNABLE_INT_FETCH("kern.hz", &hz);
170 hz = vm_guest > VM_GUEST_NO ? HZ_VM : HZ;
172 tick_sbt = SBT_1S / hz;
173 tick_bt = sbttobt(tick_sbt);
176 * Arrange for ticks to wrap 10 minutes after boot to help catch
177 * sign problems sooner.
179 ticks = INT_MAX - (hz * 10 * 60);
181 #ifdef VM_SWZONE_SIZE_MAX
182 maxswzone = VM_SWZONE_SIZE_MAX;
184 TUNABLE_LONG_FETCH("kern.maxswzone", &maxswzone);
185 #ifdef VM_BCACHE_SIZE_MAX
186 maxbcache = VM_BCACHE_SIZE_MAX;
188 TUNABLE_LONG_FETCH("kern.maxbcache", &maxbcache);
189 msgbufsize = MSGBUF_SIZE;
190 TUNABLE_INT_FETCH("kern.msgbufsize", &msgbufsize);
193 TUNABLE_ULONG_FETCH("kern.maxtsiz", &maxtsiz);
195 TUNABLE_ULONG_FETCH("kern.dfldsiz", &dfldsiz);
197 TUNABLE_ULONG_FETCH("kern.maxdsiz", &maxdsiz);
199 TUNABLE_ULONG_FETCH("kern.dflssiz", &dflssiz);
201 TUNABLE_ULONG_FETCH("kern.maxssiz", &maxssiz);
203 TUNABLE_ULONG_FETCH("kern.sgrowsiz", &sgrowsiz);
206 * Let the administrator set {NGROUPS_MAX}, but disallow values
207 * less than NGROUPS_MAX which would violate POSIX.1-2008 or
208 * greater than INT_MAX-1 which would result in overflow.
210 ngroups_max = NGROUPS_MAX;
211 TUNABLE_INT_FETCH("kern.ngroups", &ngroups_max);
212 if (ngroups_max < NGROUPS_MAX)
213 ngroups_max = NGROUPS_MAX;
216 * Only allow to lower the maximal pid.
217 * Prevent setting up a non-bootable system if pid_max is too low.
219 TUNABLE_INT_FETCH("kern.pid_max", &pid_max);
220 if (pid_max > PID_MAX)
222 else if (pid_max < 300)
225 TUNABLE_INT_FETCH("vfs.unmapped_buf_allowed", &unmapped_buf_allowed);
229 * Boot time overrides that are scaled against main memory
232 init_param2(long physpages)
235 /* Base parameters */
237 TUNABLE_INT_FETCH("kern.maxusers", &maxusers);
239 maxusers = physpages / (2 * 1024 * 1024 / PAGE_SIZE);
242 #ifdef VM_MAX_AUTOTUNE_MAXUSERS
243 if (maxusers > VM_MAX_AUTOTUNE_MAXUSERS)
244 maxusers = VM_MAX_AUTOTUNE_MAXUSERS;
247 * Scales down the function in which maxusers grows once
251 maxusers = 384 + ((maxusers - 384) / 8);
255 * The following can be overridden after boot via sysctl. Note:
256 * unless overriden, these macros are ultimately based on maxusers.
257 * Limit maxproc so that kmap entries cannot be exhausted by
261 TUNABLE_INT_FETCH("kern.maxproc", &maxproc);
262 if (maxproc > (physpages / 12))
263 maxproc = physpages / 12;
264 if (maxproc > pid_max)
266 maxprocperuid = (maxproc * 9) / 10;
269 * The default limit for maxfiles is 1/12 of the number of
270 * physical page but not less than 16 times maxusers.
271 * At most it can be 1/6 the number of physical pages.
273 maxfiles = imax(MAXFILES, physpages / 8);
274 TUNABLE_INT_FETCH("kern.maxfiles", &maxfiles);
275 if (maxfiles > (physpages / 4))
276 maxfiles = physpages / 4;
277 maxfilesperproc = (maxfiles / 10) * 9;
278 TUNABLE_INT_FETCH("kern.maxfilesperproc", &maxfilesperproc);
281 * Cannot be changed after boot.
284 TUNABLE_INT_FETCH("kern.nbuf", &nbuf);
285 TUNABLE_INT_FETCH("kern.bio_transient_maxcnt", &bio_transient_maxcnt);
288 * The default for maxpipekva is min(1/64 of the kernel address space,
289 * max(1/64 of main memory, 512KB)). See sys_pipe.c for more details.
291 maxpipekva = (physpages / 64) * PAGE_SIZE;
292 TUNABLE_LONG_FETCH("kern.ipc.maxpipekva", &maxpipekva);
293 if (maxpipekva < 512 * 1024)
294 maxpipekva = 512 * 1024;
295 if (maxpipekva > (VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS) / 64)
296 maxpipekva = (VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS) /
301 * Sysctl stringifying handler for kern.vm_guest.
304 sysctl_kern_vm_guest(SYSCTL_HANDLER_ARGS)
306 return (SYSCTL_OUT_STR(req, vm_guest_sysctl_names[vm_guest]));