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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.
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 time_t tick_seconds_max; /* max hz * seconds an integer can hold */
90 struct bintime tick_bt; /* bintime per tick (1s / hz) */
92 int maxusers; /* base tunable */
93 int maxproc; /* maximum # of processes */
94 int maxprocperuid; /* max # of procs per user */
95 int maxfiles; /* sys. wide open files limit */
96 int maxfilesperproc; /* per-proc open files limit */
97 int msgbufsize; /* size of kernel message buffer */
98 int nbuf; /* number of bcache bufs */
99 int bio_transient_maxcnt;
100 int ngroups_max; /* max # groups per process */
102 pid_t pid_max = PID_MAX;
103 u_long maxswzone; /* max swmeta KVA storage */
104 u_long maxbcache; /* max buffer cache KVA storage */
105 u_long maxpipekva; /* Limit on pipe KVA */
106 u_long maxphys; /* max raw I/O transfer size */
107 int vm_guest = VM_GUEST_NO; /* Running as virtual machine guest? */
108 u_long maxtsiz; /* max text size */
109 u_long dfldsiz; /* initial data size limit */
110 u_long maxdsiz; /* max data size */
111 u_long dflssiz; /* initial stack size limit */
112 u_long maxssiz; /* max stack size */
113 u_long sgrowsiz; /* amount to grow stack */
115 SYSCTL_INT(_kern, OID_AUTO, hz, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &hz, 0,
116 "Number of clock ticks per second");
117 SYSCTL_INT(_kern, OID_AUTO, hz_max, CTLFLAG_RD, SYSCTL_NULL_INT_PTR, HZ_MAXIMUM,
118 "Maximum hz value supported");
119 SYSCTL_INT(_kern, OID_AUTO, hz_min, CTLFLAG_RD, SYSCTL_NULL_INT_PTR, HZ_MINIMUM,
120 "Minimum hz value supported");
121 SYSCTL_INT(_kern, OID_AUTO, nbuf, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &nbuf, 0,
122 "Number of buffers in the buffer cache");
123 SYSCTL_INT(_kern, OID_AUTO, nswbuf, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &nswbuf, 0,
124 "Number of swap buffers");
125 SYSCTL_INT(_kern, OID_AUTO, msgbufsize, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &msgbufsize, 0,
126 "Size of the kernel message buffer");
127 SYSCTL_LONG(_kern, OID_AUTO, maxswzone, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &maxswzone, 0,
128 "Maximum memory for swap metadata");
129 SYSCTL_LONG(_kern, OID_AUTO, maxbcache, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &maxbcache, 0,
130 "Maximum value of vfs.maxbufspace");
131 SYSCTL_INT(_kern, OID_AUTO, bio_transient_maxcnt, CTLFLAG_RDTUN | CTLFLAG_NOFETCH,
132 &bio_transient_maxcnt, 0,
133 "Maximum number of transient BIOs mappings");
134 SYSCTL_ULONG(_kern, OID_AUTO, maxtsiz, CTLFLAG_RWTUN | CTLFLAG_NOFETCH, &maxtsiz, 0,
135 "Maximum text size");
136 SYSCTL_ULONG(_kern, OID_AUTO, dfldsiz, CTLFLAG_RWTUN | CTLFLAG_NOFETCH, &dfldsiz, 0,
137 "Initial data size limit");
138 SYSCTL_ULONG(_kern, OID_AUTO, maxdsiz, CTLFLAG_RWTUN | CTLFLAG_NOFETCH, &maxdsiz, 0,
139 "Maximum data size");
140 SYSCTL_ULONG(_kern, OID_AUTO, dflssiz, CTLFLAG_RWTUN | CTLFLAG_NOFETCH, &dflssiz, 0,
141 "Initial stack size limit");
142 SYSCTL_ULONG(_kern, OID_AUTO, maxssiz, CTLFLAG_RWTUN | CTLFLAG_NOFETCH, &maxssiz, 0,
143 "Maximum stack size");
144 SYSCTL_ULONG(_kern, OID_AUTO, sgrowsiz, CTLFLAG_RWTUN | CTLFLAG_NOFETCH, &sgrowsiz, 0,
145 "Amount to grow stack on a stack fault");
146 SYSCTL_PROC(_kern, OID_AUTO, vm_guest,
147 CTLFLAG_RD | CTLTYPE_STRING | CTLFLAG_MPSAFE, NULL, 0,
148 sysctl_kern_vm_guest, "A",
149 "Virtual machine guest detected?");
152 * The elements of this array are ordered based upon the values of the
153 * corresponding enum VM_GUEST members.
155 static const char *const vm_guest_sysctl_names[] = {
156 [VM_GUEST_NO] = "none",
157 [VM_GUEST_VM] = "generic",
158 [VM_GUEST_XEN] = "xen",
159 [VM_GUEST_HV] = "hv",
160 [VM_GUEST_VMWARE] = "vmware",
161 [VM_GUEST_KVM] = "kvm",
162 [VM_GUEST_BHYVE] = "bhyve",
163 [VM_GUEST_VBOX] = "vbox",
164 [VM_GUEST_PARALLELS] = "parallels",
167 CTASSERT(nitems(vm_guest_sysctl_names) - 1 == VM_LAST);
170 * Boot time overrides that are not scaled against main memory
179 * arm64 and riscv currently hard-code the thread0 kstack size
180 * to KSTACK_PAGES, ignoring the tunable.
182 #if !defined(__mips__)
183 TUNABLE_INT_FETCH("kern.kstack_pages", &kstack_pages);
187 TUNABLE_INT_FETCH("kern.hz", &hz);
189 hz = vm_guest > VM_GUEST_NO ? HZ_VM : HZ;
191 /* range check the "hz" value */
192 if (__predict_false(hz < HZ_MINIMUM))
194 else if (__predict_false(hz > HZ_MAXIMUM))
198 tick_sbt = SBT_1S / hz;
199 tick_bt = sbttobt(tick_sbt);
200 tick_seconds_max = INT_MAX / hz;
203 * Arrange for ticks to wrap 10 minutes after boot to help catch
204 * sign problems sooner.
206 ticks = INT_MAX - (hz * 10 * 60);
208 vn_lock_pair_pause_max = hz / 100;
209 if (vn_lock_pair_pause_max == 0)
210 vn_lock_pair_pause_max = 1;
212 #ifdef VM_SWZONE_SIZE_MAX
213 maxswzone = VM_SWZONE_SIZE_MAX;
215 TUNABLE_LONG_FETCH("kern.maxswzone", &maxswzone);
216 #ifdef VM_BCACHE_SIZE_MAX
217 maxbcache = VM_BCACHE_SIZE_MAX;
219 TUNABLE_LONG_FETCH("kern.maxbcache", &maxbcache);
220 msgbufsize = MSGBUF_SIZE;
221 TUNABLE_INT_FETCH("kern.msgbufsize", &msgbufsize);
224 TUNABLE_ULONG_FETCH("kern.maxtsiz", &maxtsiz);
226 TUNABLE_ULONG_FETCH("kern.dfldsiz", &dfldsiz);
228 TUNABLE_ULONG_FETCH("kern.maxdsiz", &maxdsiz);
230 TUNABLE_ULONG_FETCH("kern.dflssiz", &dflssiz);
232 TUNABLE_ULONG_FETCH("kern.maxssiz", &maxssiz);
234 TUNABLE_ULONG_FETCH("kern.sgrowsiz", &sgrowsiz);
237 * Let the administrator set {NGROUPS_MAX}, but disallow values
238 * less than NGROUPS_MAX which would violate POSIX.1-2008 or
239 * greater than INT_MAX-1 which would result in overflow.
241 ngroups_max = NGROUPS_MAX;
242 TUNABLE_INT_FETCH("kern.ngroups", &ngroups_max);
243 if (ngroups_max < NGROUPS_MAX)
244 ngroups_max = NGROUPS_MAX;
247 * Only allow to lower the maximal pid.
248 * Prevent setting up a non-bootable system if pid_max is too low.
250 TUNABLE_INT_FETCH("kern.pid_max", &pid_max);
251 if (pid_max > PID_MAX)
253 else if (pid_max < 300)
256 TUNABLE_INT_FETCH("vfs.unmapped_buf_allowed", &unmapped_buf_allowed);
260 * Boot time overrides that are scaled against main memory
263 init_param2(long physpages)
266 /* Base parameters */
268 TUNABLE_INT_FETCH("kern.maxusers", &maxusers);
270 maxusers = physpages / (2 * 1024 * 1024 / PAGE_SIZE);
273 #ifdef VM_MAX_AUTOTUNE_MAXUSERS
274 if (maxusers > VM_MAX_AUTOTUNE_MAXUSERS)
275 maxusers = VM_MAX_AUTOTUNE_MAXUSERS;
278 * Scales down the function in which maxusers grows once
282 maxusers = 384 + ((maxusers - 384) / 8);
286 * The following can be overridden after boot via sysctl. Note:
287 * unless overridden, these macros are ultimately based on maxusers.
288 * Limit maxproc so that kmap entries cannot be exhausted by
292 TUNABLE_INT_FETCH("kern.maxproc", &maxproc);
293 if (maxproc > (physpages / 12))
294 maxproc = physpages / 12;
295 if (maxproc > pid_max)
297 maxprocperuid = (maxproc * 9) / 10;
300 * The default limit for maxfiles is 1/12 of the number of
301 * physical page but not less than 16 times maxusers.
302 * At most it can be 1/6 the number of physical pages.
304 maxfiles = imax(MAXFILES, physpages / 8);
305 TUNABLE_INT_FETCH("kern.maxfiles", &maxfiles);
306 if (maxfiles > (physpages / 4))
307 maxfiles = physpages / 4;
308 maxfilesperproc = (maxfiles / 10) * 9;
309 TUNABLE_INT_FETCH("kern.maxfilesperproc", &maxfilesperproc);
312 * Cannot be changed after boot.
315 TUNABLE_INT_FETCH("kern.nbuf", &nbuf);
316 TUNABLE_INT_FETCH("kern.bio_transient_maxcnt", &bio_transient_maxcnt);
318 TUNABLE_ULONG_FETCH("kern.maxphys", &maxphys);
321 } else if (__bitcountl(maxphys) != 1) { /* power of two */
322 if (flsl(maxphys) == NBBY * sizeof(maxphys))
325 maxphys = 1UL << flsl(maxphys);
327 if (maxphys < PAGE_SIZE)
331 * Physical buffers are pre-allocated buffers (struct buf) that
332 * are used as temporary holders for I/O, such as paging I/O.
334 TUNABLE_INT_FETCH("kern.nswbuf", &nswbuf);
337 * The default for maxpipekva is min(1/64 of the kernel address space,
338 * max(1/64 of main memory, 512KB)). See sys_pipe.c for more details.
340 maxpipekva = ptoa(physpages / 64);
341 TUNABLE_LONG_FETCH("kern.ipc.maxpipekva", &maxpipekva);
342 if (maxpipekva < 512 * 1024)
343 maxpipekva = 512 * 1024;
344 if (maxpipekva > (VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS) / 64)
345 maxpipekva = (VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS) /
350 * Sysctl stringifying handler for kern.vm_guest.
353 sysctl_kern_vm_guest(SYSCTL_HANDLER_ARGS)
355 return (SYSCTL_OUT_STR(req, vm_guest_sysctl_names[vm_guest]));