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36 * @(#)param.c 8.3 (Berkeley) 8/20/94
39 #include <sys/cdefs.h>
40 #include "opt_param.h"
41 #include "opt_msgbuf.h"
42 #include "opt_maxphys.h"
43 #include "opt_maxusers.h"
45 #include <sys/param.h>
46 #include <sys/systm.h>
48 #include <sys/kernel.h>
49 #include <sys/limits.h>
50 #include <sys/msgbuf.h>
51 #include <sys/sysctl.h>
53 #include <sys/vnode.h>
56 #include <vm/vm_param.h>
60 * System parameter formulae.
73 #define NPROC (20 + 16 * maxusers)
78 #define MAXFILES (40 + 32 * maxusers)
81 static int sysctl_kern_vm_guest(SYSCTL_HANDLER_ARGS);
83 int hz; /* system clock's frequency */
84 int tick; /* usec per tick (1000000 / hz) */
85 time_t tick_seconds_max; /* max hz * seconds an integer can hold */
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 */
94 int nbuf; /* number of bcache bufs */
95 int bio_transient_maxcnt;
96 int ngroups_max; /* max # groups per process */
98 pid_t pid_max = PID_MAX;
99 u_long maxswzone; /* max swmeta KVA storage */
100 u_long maxbcache; /* max buffer cache KVA storage */
101 u_long maxpipekva; /* Limit on pipe KVA */
102 u_long maxphys; /* max raw I/O transfer size */
103 int vm_guest = VM_GUEST_NO; /* Running as virtual machine guest? */
104 u_long maxtsiz; /* max text size */
105 u_long dfldsiz; /* initial data size limit */
106 u_long maxdsiz; /* max data size */
107 u_long dflssiz; /* initial stack size limit */
108 u_long maxssiz; /* max stack size */
109 u_long sgrowsiz; /* amount to grow stack */
111 SYSCTL_INT(_kern, OID_AUTO, hz, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &hz, 0,
112 "Number of clock ticks per second");
113 SYSCTL_INT(_kern, OID_AUTO, hz_max, CTLFLAG_RD, SYSCTL_NULL_INT_PTR, HZ_MAXIMUM,
114 "Maximum hz value supported");
115 SYSCTL_INT(_kern, OID_AUTO, hz_min, CTLFLAG_RD, SYSCTL_NULL_INT_PTR, HZ_MINIMUM,
116 "Minimum hz value supported");
117 SYSCTL_INT(_kern, OID_AUTO, nbuf, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &nbuf, 0,
118 "Number of buffers in the buffer cache");
119 SYSCTL_INT(_kern, OID_AUTO, nswbuf, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &nswbuf, 0,
120 "Number of swap buffers");
121 SYSCTL_INT(_kern, OID_AUTO, msgbufsize, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &msgbufsize, 0,
122 "Size of the kernel message buffer");
123 SYSCTL_LONG(_kern, OID_AUTO, maxswzone, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &maxswzone, 0,
124 "Maximum memory for swap metadata");
125 SYSCTL_LONG(_kern, OID_AUTO, maxbcache, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &maxbcache, 0,
126 "Maximum value of vfs.maxbufspace");
127 SYSCTL_INT(_kern, OID_AUTO, bio_transient_maxcnt, CTLFLAG_RDTUN | CTLFLAG_NOFETCH,
128 &bio_transient_maxcnt, 0,
129 "Maximum number of transient BIOs mappings");
130 SYSCTL_ULONG(_kern, OID_AUTO, maxtsiz, CTLFLAG_RWTUN | CTLFLAG_NOFETCH, &maxtsiz, 0,
131 "Maximum text size");
132 SYSCTL_ULONG(_kern, OID_AUTO, dfldsiz, CTLFLAG_RWTUN | CTLFLAG_NOFETCH, &dfldsiz, 0,
133 "Initial data size limit");
134 SYSCTL_ULONG(_kern, OID_AUTO, maxdsiz, CTLFLAG_RWTUN | CTLFLAG_NOFETCH, &maxdsiz, 0,
135 "Maximum data size");
136 SYSCTL_ULONG(_kern, OID_AUTO, dflssiz, CTLFLAG_RWTUN | CTLFLAG_NOFETCH, &dflssiz, 0,
137 "Initial stack size limit");
138 SYSCTL_ULONG(_kern, OID_AUTO, maxssiz, CTLFLAG_RWTUN | CTLFLAG_NOFETCH, &maxssiz, 0,
139 "Maximum stack size");
140 SYSCTL_ULONG(_kern, OID_AUTO, sgrowsiz, CTLFLAG_RWTUN | CTLFLAG_NOFETCH, &sgrowsiz, 0,
141 "Amount to grow stack on a stack fault");
142 SYSCTL_PROC(_kern, OID_AUTO, vm_guest,
143 CTLFLAG_RD | CTLTYPE_STRING | CTLFLAG_MPSAFE, NULL, 0,
144 sysctl_kern_vm_guest, "A",
145 "Virtual machine guest detected?");
148 * The elements of this array are ordered based upon the values of the
149 * corresponding enum VM_GUEST members.
151 static const char *const vm_guest_sysctl_names[] = {
152 [VM_GUEST_NO] = "none",
153 [VM_GUEST_VM] = "generic",
154 [VM_GUEST_XEN] = "xen",
155 [VM_GUEST_HV] = "hv",
156 [VM_GUEST_VMWARE] = "vmware",
157 [VM_GUEST_KVM] = "kvm",
158 [VM_GUEST_BHYVE] = "bhyve",
159 [VM_GUEST_VBOX] = "vbox",
160 [VM_GUEST_PARALLELS] = "parallels",
163 CTASSERT(nitems(vm_guest_sysctl_names) - 1 == VM_LAST);
166 * Boot time overrides that are not scaled against main memory
173 #if !defined(__arm64__)
174 TUNABLE_INT_FETCH("kern.kstack_pages", &kstack_pages);
177 TUNABLE_INT_FETCH("kern.hz", &hz);
179 hz = vm_guest > VM_GUEST_NO ? HZ_VM : HZ;
181 /* range check the "hz" value */
182 if (__predict_false(hz < HZ_MINIMUM))
184 else if (__predict_false(hz > HZ_MAXIMUM))
188 tick_sbt = SBT_1S / hz;
189 tick_bt = sbttobt(tick_sbt);
190 tick_seconds_max = INT_MAX / hz;
193 * Arrange for ticks to wrap 10 minutes after boot to help catch
194 * sign problems sooner.
196 ticks = INT_MAX - (hz * 10 * 60);
198 vn_lock_pair_pause_max = hz / 100;
199 if (vn_lock_pair_pause_max == 0)
200 vn_lock_pair_pause_max = 1;
202 #ifdef VM_SWZONE_SIZE_MAX
203 maxswzone = VM_SWZONE_SIZE_MAX;
205 TUNABLE_LONG_FETCH("kern.maxswzone", &maxswzone);
206 #ifdef VM_BCACHE_SIZE_MAX
207 maxbcache = VM_BCACHE_SIZE_MAX;
209 TUNABLE_LONG_FETCH("kern.maxbcache", &maxbcache);
210 msgbufsize = MSGBUF_SIZE;
211 TUNABLE_INT_FETCH("kern.msgbufsize", &msgbufsize);
214 TUNABLE_ULONG_FETCH("kern.maxtsiz", &maxtsiz);
216 TUNABLE_ULONG_FETCH("kern.dfldsiz", &dfldsiz);
218 TUNABLE_ULONG_FETCH("kern.maxdsiz", &maxdsiz);
220 TUNABLE_ULONG_FETCH("kern.dflssiz", &dflssiz);
222 TUNABLE_ULONG_FETCH("kern.maxssiz", &maxssiz);
224 TUNABLE_ULONG_FETCH("kern.sgrowsiz", &sgrowsiz);
227 * Let the administrator set {NGROUPS_MAX}, but disallow values
228 * less than NGROUPS_MAX which would violate POSIX.1-2008 or
229 * greater than INT_MAX-1 which would result in overflow.
231 ngroups_max = NGROUPS_MAX;
232 TUNABLE_INT_FETCH("kern.ngroups", &ngroups_max);
233 if (ngroups_max < NGROUPS_MAX)
234 ngroups_max = NGROUPS_MAX;
237 * Only allow to lower the maximal pid.
238 * Prevent setting up a non-bootable system if pid_max is too low.
240 TUNABLE_INT_FETCH("kern.pid_max", &pid_max);
241 if (pid_max > PID_MAX)
243 else if (pid_max < 300)
246 TUNABLE_INT_FETCH("vfs.unmapped_buf_allowed", &unmapped_buf_allowed);
251 * Boot time overrides that are scaled against main memory
254 init_param2(long physpages)
258 /* Base parameters */
260 TUNABLE_INT_FETCH("kern.maxusers", &maxusers);
262 maxusers = physpages / (2 * 1024 * 1024 / PAGE_SIZE);
265 #ifdef VM_MAX_AUTOTUNE_MAXUSERS
266 if (maxusers > VM_MAX_AUTOTUNE_MAXUSERS)
267 maxusers = VM_MAX_AUTOTUNE_MAXUSERS;
270 * Scales down the function in which maxusers grows once
274 maxusers = 384 + ((maxusers - 384) / 8);
278 * The following can be overridden after boot via sysctl. Note:
279 * unless overridden, these macros are ultimately based on maxusers.
280 * Limit maxproc so that kmap entries cannot be exhausted by
284 TUNABLE_INT_FETCH("kern.maxproc", &maxproc);
285 if (maxproc > (physpages / 12))
286 maxproc = physpages / 12;
287 if (maxproc > pid_max)
289 maxprocperuid = (maxproc * 9) / 10;
292 * The default limit for maxfiles is 1/12 of the number of
293 * physical page but not less than 16 times maxusers.
294 * At most it can be 1/6 the number of physical pages.
296 maxfiles = imax(MAXFILES, physpages / 8);
297 TUNABLE_INT_FETCH("kern.maxfiles", &maxfiles);
298 if (maxfiles > (physpages / 4))
299 maxfiles = physpages / 4;
300 maxfilesperproc = (maxfiles / 10) * 9;
301 TUNABLE_INT_FETCH("kern.maxfilesperproc", &maxfilesperproc);
304 * Cannot be changed after boot.
307 TUNABLE_INT_FETCH("kern.nbuf", &nbuf);
308 TUNABLE_INT_FETCH("kern.bio_transient_maxcnt", &bio_transient_maxcnt);
310 TUNABLE_ULONG_FETCH("kern.maxphys", &maxphys);
313 } else if (__bitcountl(maxphys) != 1) { /* power of two */
314 if (flsl(maxphys) == NBBY * sizeof(maxphys))
317 maxphys = 1UL << flsl(maxphys);
319 if (maxphys < PAGE_SIZE)
323 * Physical buffers are pre-allocated buffers (struct buf) that
324 * are used as temporary holders for I/O, such as paging I/O.
326 TUNABLE_INT_FETCH("kern.nswbuf", &nswbuf);
329 * The default for maxpipekva is min(1/64 of the kernel address space,
330 * max(1/64 of main memory, 512KB)). See sys_pipe.c for more details.
332 maxpipekva = ptoa(physpages / 64);
333 TUNABLE_LONG_FETCH("kern.ipc.maxpipekva", &maxpipekva);
334 if (maxpipekva < 512 * 1024)
335 maxpipekva = 512 * 1024;
336 if (maxpipekva > (VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS) / 64)
337 maxpipekva = (VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS) /
343 * Sysctl stringifying handler for kern.vm_guest.
346 sysctl_kern_vm_guest(SYSCTL_HANDLER_ARGS)
348 return (SYSCTL_OUT_STR(req, vm_guest_sysctl_names[vm_guest]));