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6 * (c) UNIX System Laboratories, Inc.
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36 * @(#)param.c 8.3 (Berkeley) 8/20/94
39 #include <sys/cdefs.h>
40 __FBSDID("$FreeBSD$");
42 #include "opt_param.h"
43 #include "opt_msgbuf.h"
44 #include "opt_maxusers.h"
46 #include <sys/param.h>
47 #include <sys/systm.h>
49 #include <sys/kernel.h>
50 #include <sys/limits.h>
51 #include <sys/msgbuf.h>
52 #include <sys/sysctl.h>
56 #include <vm/vm_param.h>
60 * System parameter formulae.
64 # if defined(__mips__) || defined(__arm__)
77 #define NPROC (20 + 16 * maxusers)
82 #define MAXFILES (40 + 32 * maxusers)
85 static int sysctl_kern_vm_guest(SYSCTL_HANDLER_ARGS);
87 int hz; /* system clock's frequency */
88 int tick; /* usec per tick (1000000 / hz) */
89 struct bintime tick_bt; /* bintime per tick (1s / hz) */
91 int maxusers; /* base tunable */
92 int maxproc; /* maximum # of processes */
93 int maxprocperuid; /* max # of procs per user */
94 int maxfiles; /* sys. wide open files limit */
95 int maxfilesperproc; /* per-proc open files limit */
96 int msgbufsize; /* size of kernel message buffer */
98 int bio_transient_maxcnt;
99 int ngroups_max; /* max # groups per process */
101 pid_t pid_max = PID_MAX;
102 long maxswzone; /* max swmeta KVA storage */
103 long maxbcache; /* max buffer cache KVA storage */
104 long maxpipekva; /* Limit on pipe KVA */
105 int vm_guest = VM_GUEST_NO; /* Running as virtual machine guest? */
106 u_long maxtsiz; /* max text size */
107 u_long dfldsiz; /* initial data size limit */
108 u_long maxdsiz; /* max data size */
109 u_long dflssiz; /* initial stack size limit */
110 u_long maxssiz; /* max stack size */
111 u_long sgrowsiz; /* amount to grow stack */
113 SYSCTL_INT(_kern, OID_AUTO, hz, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &hz, 0,
114 "Number of clock ticks per second");
115 SYSCTL_INT(_kern, OID_AUTO, nbuf, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &nbuf, 0,
116 "Number of buffers in the buffer cache");
117 SYSCTL_INT(_kern, OID_AUTO, nswbuf, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &nswbuf, 0,
118 "Number of swap buffers");
119 SYSCTL_INT(_kern, OID_AUTO, msgbufsize, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &msgbufsize, 0,
120 "Size of the kernel message buffer");
121 SYSCTL_LONG(_kern, OID_AUTO, maxswzone, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &maxswzone, 0,
122 "Maximum memory for swap metadata");
123 SYSCTL_LONG(_kern, OID_AUTO, maxbcache, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &maxbcache, 0,
124 "Maximum value of vfs.maxbufspace");
125 SYSCTL_INT(_kern, OID_AUTO, bio_transient_maxcnt, CTLFLAG_RDTUN | CTLFLAG_NOFETCH,
126 &bio_transient_maxcnt, 0,
127 "Maximum number of transient BIOs mappings");
128 SYSCTL_ULONG(_kern, OID_AUTO, maxtsiz, CTLFLAG_RWTUN | CTLFLAG_NOFETCH, &maxtsiz, 0,
129 "Maximum text size");
130 SYSCTL_ULONG(_kern, OID_AUTO, dfldsiz, CTLFLAG_RWTUN | CTLFLAG_NOFETCH, &dfldsiz, 0,
131 "Initial data size limit");
132 SYSCTL_ULONG(_kern, OID_AUTO, maxdsiz, CTLFLAG_RWTUN | CTLFLAG_NOFETCH, &maxdsiz, 0,
133 "Maximum data size");
134 SYSCTL_ULONG(_kern, OID_AUTO, dflssiz, CTLFLAG_RWTUN | CTLFLAG_NOFETCH, &dflssiz, 0,
135 "Initial stack size limit");
136 SYSCTL_ULONG(_kern, OID_AUTO, maxssiz, CTLFLAG_RWTUN | CTLFLAG_NOFETCH, &maxssiz, 0,
137 "Maximum stack size");
138 SYSCTL_ULONG(_kern, OID_AUTO, sgrowsiz, CTLFLAG_RWTUN | CTLFLAG_NOFETCH, &sgrowsiz, 0,
139 "Amount to grow stack on a stack fault");
140 SYSCTL_PROC(_kern, OID_AUTO, vm_guest,
141 CTLFLAG_RD | CTLTYPE_STRING | CTLFLAG_MPSAFE, NULL, 0,
142 sysctl_kern_vm_guest, "A",
143 "Virtual machine guest detected?");
146 * The elements of this array are ordered based upon the values of the
147 * corresponding enum VM_GUEST members.
149 static const char *const vm_guest_sysctl_names[] = {
150 [VM_GUEST_NO] = "none",
151 [VM_GUEST_VM] = "generic",
152 [VM_GUEST_XEN] = "xen",
153 [VM_GUEST_HV] = "hv",
154 [VM_GUEST_VMWARE] = "vmware",
155 [VM_GUEST_KVM] = "kvm",
156 [VM_GUEST_BHYVE] = "bhyve",
157 [VM_GUEST_VBOX] = "vbox",
158 [VM_GUEST_PARALLELS] = "parallels",
161 CTASSERT(nitems(vm_guest_sysctl_names) - 1 == VM_LAST);
164 * Boot time overrides that are not scaled against main memory
170 #if !defined(__mips__) && !defined(__arm64__)
171 TUNABLE_INT_FETCH("kern.kstack_pages", &kstack_pages);
174 TUNABLE_INT_FETCH("kern.hz", &hz);
176 hz = vm_guest > VM_GUEST_NO ? HZ_VM : HZ;
178 tick_sbt = SBT_1S / hz;
179 tick_bt = sbttobt(tick_sbt);
182 * Arrange for ticks to wrap 10 minutes after boot to help catch
183 * sign problems sooner.
185 ticks = INT_MAX - (hz * 10 * 60);
187 #ifdef VM_SWZONE_SIZE_MAX
188 maxswzone = VM_SWZONE_SIZE_MAX;
190 TUNABLE_LONG_FETCH("kern.maxswzone", &maxswzone);
191 #ifdef VM_BCACHE_SIZE_MAX
192 maxbcache = VM_BCACHE_SIZE_MAX;
194 TUNABLE_LONG_FETCH("kern.maxbcache", &maxbcache);
195 msgbufsize = MSGBUF_SIZE;
196 TUNABLE_INT_FETCH("kern.msgbufsize", &msgbufsize);
199 TUNABLE_ULONG_FETCH("kern.maxtsiz", &maxtsiz);
201 TUNABLE_ULONG_FETCH("kern.dfldsiz", &dfldsiz);
203 TUNABLE_ULONG_FETCH("kern.maxdsiz", &maxdsiz);
205 TUNABLE_ULONG_FETCH("kern.dflssiz", &dflssiz);
207 TUNABLE_ULONG_FETCH("kern.maxssiz", &maxssiz);
209 TUNABLE_ULONG_FETCH("kern.sgrowsiz", &sgrowsiz);
212 * Let the administrator set {NGROUPS_MAX}, but disallow values
213 * less than NGROUPS_MAX which would violate POSIX.1-2008 or
214 * greater than INT_MAX-1 which would result in overflow.
216 ngroups_max = NGROUPS_MAX;
217 TUNABLE_INT_FETCH("kern.ngroups", &ngroups_max);
218 if (ngroups_max < NGROUPS_MAX)
219 ngroups_max = NGROUPS_MAX;
222 * Only allow to lower the maximal pid.
223 * Prevent setting up a non-bootable system if pid_max is too low.
225 TUNABLE_INT_FETCH("kern.pid_max", &pid_max);
226 if (pid_max > PID_MAX)
228 else if (pid_max < 300)
231 TUNABLE_INT_FETCH("vfs.unmapped_buf_allowed", &unmapped_buf_allowed);
235 * Boot time overrides that are scaled against main memory
238 init_param2(long physpages)
241 /* Base parameters */
243 TUNABLE_INT_FETCH("kern.maxusers", &maxusers);
245 maxusers = physpages / (2 * 1024 * 1024 / PAGE_SIZE);
248 #ifdef VM_MAX_AUTOTUNE_MAXUSERS
249 if (maxusers > VM_MAX_AUTOTUNE_MAXUSERS)
250 maxusers = VM_MAX_AUTOTUNE_MAXUSERS;
253 * Scales down the function in which maxusers grows once
257 maxusers = 384 + ((maxusers - 384) / 8);
261 * The following can be overridden after boot via sysctl. Note:
262 * unless overriden, these macros are ultimately based on maxusers.
263 * Limit maxproc so that kmap entries cannot be exhausted by
267 TUNABLE_INT_FETCH("kern.maxproc", &maxproc);
268 if (maxproc > (physpages / 12))
269 maxproc = physpages / 12;
270 if (maxproc > pid_max)
272 maxprocperuid = (maxproc * 9) / 10;
275 * The default limit for maxfiles is 1/12 of the number of
276 * physical page but not less than 16 times maxusers.
277 * At most it can be 1/6 the number of physical pages.
279 maxfiles = imax(MAXFILES, physpages / 8);
280 TUNABLE_INT_FETCH("kern.maxfiles", &maxfiles);
281 if (maxfiles > (physpages / 4))
282 maxfiles = physpages / 4;
283 maxfilesperproc = (maxfiles / 10) * 9;
284 TUNABLE_INT_FETCH("kern.maxfilesperproc", &maxfilesperproc);
287 * Cannot be changed after boot.
290 TUNABLE_INT_FETCH("kern.nbuf", &nbuf);
291 TUNABLE_INT_FETCH("kern.bio_transient_maxcnt", &bio_transient_maxcnt);
294 * Physical buffers are pre-allocated buffers (struct buf) that
295 * are used as temporary holders for I/O, such as paging I/O.
297 TUNABLE_INT_FETCH("kern.nswbuf", &nswbuf);
300 * The default for maxpipekva is min(1/64 of the kernel address space,
301 * max(1/64 of main memory, 512KB)). See sys_pipe.c for more details.
303 maxpipekva = (physpages / 64) * PAGE_SIZE;
304 TUNABLE_LONG_FETCH("kern.ipc.maxpipekva", &maxpipekva);
305 if (maxpipekva < 512 * 1024)
306 maxpipekva = 512 * 1024;
307 if (maxpipekva > (VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS) / 64)
308 maxpipekva = (VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS) /
313 * Sysctl stringifying handler for kern.vm_guest.
316 sysctl_kern_vm_guest(SYSCTL_HANDLER_ARGS)
318 return (SYSCTL_OUT_STR(req, vm_guest_sysctl_names[vm_guest]));