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