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38 * @(#)param.c 8.3 (Berkeley) 8/20/94
39 * $FreeBSD: src/sys/kern/subr_param.c,v 1.42.2.10 2002/03/09 21:05:47 silby Exp $
40 * $DragonFly: src/sys/kern/subr_param.c,v 1.7 2005/06/26 22:03:22 dillon Exp $
43 #include "opt_param.h"
44 #include "opt_maxusers.h"
46 #include <sys/param.h>
47 #include <sys/systm.h>
48 #include <sys/kernel.h>
49 #include <sys/malloc.h>
51 #include <machine/vmparam.h>
54 * System parameter formulae.
60 #define NPROC (20 + 16 * maxusers)
65 #define MAXFILES (maxproc * 16)
67 #ifndef MAXPOSIXLOCKSPERUID
68 #define MAXPOSIXLOCKSPERUID (maxusers * 64) /* Should be a safe value */
74 int ustick; /* tick interval in microseconds */
75 int nstick; /* tick interval in nanoseconds */
76 int maxusers; /* base tunable */
77 int maxproc; /* maximum # of processes */
78 int maxprocperuid; /* max # of procs per user */
79 int maxfiles; /* system wide open files limit */
80 int maxfilesrootres; /* descriptors reserved for root use */
81 int minfilesperproc; /* per-proc min open files (safety) */
82 int maxfilesperproc; /* per-proc open files limit */
83 int maxfilesperuser; /* per-user open files limit */
84 int maxposixlocksperuid; /* max # POSIX locks per uid */
85 int ncallout; /* maximum # of timer events */
86 int mbuf_wait = 32; /* mbuf sleep time in ticks */
89 long maxswzone; /* max swmeta KVA storage */
90 long maxbcache; /* max buffer cache KVA storage */
91 int vmm_guest = 0; /* Running as virtual machine guest? */
92 u_quad_t maxtsiz; /* max text size */
93 u_quad_t dfldsiz; /* initial data size limit */
94 u_quad_t maxdsiz; /* max data size */
95 u_quad_t dflssiz; /* initial stack size limit */
96 u_quad_t maxssiz; /* max stack size */
97 u_quad_t sgrowsiz; /* amount to grow stack */
100 * These have to be allocated somewhere; allocating
101 * them here forces loader errors if this file is omitted
102 * (if they've been externed everywhere else; hah!).
107 * Boot time overrides that are not scaled against main memory
113 TUNABLE_INT_FETCH("kern.hz", &hz);
114 stathz = hz * 128 / 100;
116 ustick = 1000000 / hz;
117 nstick = 1000000000 / hz;
118 /* can adjust 30ms in 60s */
119 ntp_default_tick_delta = howmany(30000000, 60 * hz);
121 #ifdef VM_SWZONE_SIZE_MAX
122 maxswzone = VM_SWZONE_SIZE_MAX;
124 TUNABLE_LONG_FETCH("kern.maxswzone", &maxswzone);
125 #ifdef VM_BCACHE_SIZE_MAX
126 maxbcache = VM_BCACHE_SIZE_MAX;
128 TUNABLE_LONG_FETCH("kern.maxbcache", &maxbcache);
130 TUNABLE_QUAD_FETCH("kern.maxtsiz", &maxtsiz);
132 TUNABLE_QUAD_FETCH("kern.dfldsiz", &dfldsiz);
134 TUNABLE_QUAD_FETCH("kern.maxdsiz", &maxdsiz);
136 TUNABLE_QUAD_FETCH("kern.dflssiz", &dflssiz);
138 TUNABLE_QUAD_FETCH("kern.maxssiz", &maxssiz);
140 TUNABLE_QUAD_FETCH("kern.sgrowsiz", &sgrowsiz);
144 * Boot time overrides that are scaled against main memory
147 init_param2(int physpages)
152 * Calculate manually becaus the VM page queues / system is not set up yet
154 limsize = (size_t)physpages * PAGE_SIZE;
155 if (limsize > KvaSize)
157 limsize /= 1024 * 1024; /* smaller of KVM or physmem in MB */
159 /* Base parameters */
161 TUNABLE_INT_FETCH("kern.maxusers", &maxusers);
163 maxusers = limsize / 8; /* ~384 per 3G */
170 * The following can be overridden after boot via sysctl. Note:
171 * unless overriden, these macros are ultimately based on maxusers.
173 * Limit maxproc so that kmap entries cannot be exhausted by
177 TUNABLE_INT_FETCH("kern.maxproc", &maxproc);
180 if (maxproc > limsize * 21)
181 maxproc = limsize * 21;
184 * Maximum number of open files
187 TUNABLE_INT_FETCH("kern.maxfiles", &maxfiles);
192 * Limit file descriptors so no single user can exhaust the
195 * WARNING: Do not set minfilesperproc too high or the user
196 * can exhaust the system with a combination of fork()
197 * and open(). Actual worst case is:
199 * (minfilesperproc * maxprocperuid) + maxfilesperuser
201 maxprocperuid = maxproc / 4;
202 if (maxprocperuid < 128)
203 maxprocperuid = maxproc / 2;
205 maxfilesperproc = maxfiles / 4;
206 maxfilesperuser = maxfilesperproc * 2;
207 maxfilesrootres = maxfiles / 20;
210 * Severe hack to try to prevent pipe() descriptors from
211 * blowing away kernel memory.
213 if (KvaSize <= (vm_offset_t)(1536LL * 1024 * 1024) &&
214 maxfilesperuser > 20000) {
215 maxfilesperuser = 20000;
218 maxposixlocksperuid = MAXPOSIXLOCKSPERUID;
219 TUNABLE_INT_FETCH("kern.maxposixlocksperuid", &maxposixlocksperuid);
222 * Unless overriden, NBUF is typically 0 (auto-sized later).
225 TUNABLE_INT_FETCH("kern.nbuf", &nbuf);
227 ncallout = 16 + maxproc + maxfiles;
228 TUNABLE_INT_FETCH("kern.ncallout", &ncallout);