4 * Copyright (c) 1991, 1993
5 * The Regents of the University of California. All rights reserved.
7 * This code is derived from software contributed to Berkeley by
8 * The Mach Operating System project at Carnegie-Mellon University.
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. All advertising materials mentioning features or use of this software
19 * must display the following acknowledgement:
20 * This product includes software developed by the University of
21 * California, Berkeley and its contributors.
22 * 4. Neither the name of the University nor the names of its contributors
23 * may be used to endorse or promote products derived from this software
24 * without specific prior written permission.
26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
38 * from: @(#)vm_glue.c 8.6 (Berkeley) 1/5/94
41 * Copyright (c) 1987, 1990 Carnegie-Mellon University.
42 * All rights reserved.
44 * Permission to use, copy, modify and distribute this software and
45 * its documentation is hereby granted, provided that both the copyright
46 * notice and this permission notice appear in all copies of the
47 * software, derivative works or modified versions, and any portions
48 * thereof, and that both notices appear in supporting documentation.
50 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
51 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
52 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
54 * Carnegie Mellon requests users of this software to return to
56 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
57 * School of Computer Science
58 * Carnegie Mellon University
59 * Pittsburgh PA 15213-3890
61 * any improvements or extensions that they make and grant Carnegie the
62 * rights to redistribute these changes.
64 * $FreeBSD: src/sys/vm/vm_glue.c,v 1.94.2.4 2003/01/13 22:51:17 dillon Exp $
65 * $DragonFly: src/sys/vm/vm_glue.c,v 1.56 2008/07/01 02:02:56 dillon Exp $
70 #include <sys/param.h>
71 #include <sys/systm.h>
73 #include <sys/resourcevar.h>
76 #include <sys/vmmeter.h>
77 #include <sys/sysctl.h>
79 #include <sys/kernel.h>
80 #include <sys/unistd.h>
82 #include <machine/limits.h>
85 #include <vm/vm_param.h>
88 #include <vm/vm_map.h>
89 #include <vm/vm_page.h>
90 #include <vm/vm_pageout.h>
91 #include <vm/vm_kern.h>
92 #include <vm/vm_extern.h>
95 #include <vm/vm_page2.h>
96 #include <sys/thread2.h>
97 #include <sys/sysref2.h>
100 * THIS MUST BE THE LAST INITIALIZATION ITEM!!!
102 * Note: run scheduling should be divorced from the vm system.
104 static void scheduler (void *);
105 SYSINIT(scheduler, SI_SUB_RUN_SCHEDULER, SI_ORDER_FIRST, scheduler, NULL)
109 static int swap_debug = 0;
110 SYSCTL_INT(_vm, OID_AUTO, swap_debug,
111 CTLFLAG_RW, &swap_debug, 0, "");
115 static int scheduler_notify;
117 static void swapout (struct proc *);
123 kernacc(c_caddr_t addr, int len, int rw)
126 vm_offset_t saddr, eaddr;
129 KASSERT((rw & (~VM_PROT_ALL)) == 0,
130 ("illegal ``rw'' argument to kernacc (%x)\n", rw));
133 * The globaldata space is not part of the kernel_map proper,
134 * check access separately.
136 if (is_globaldata_space((vm_offset_t)addr, (vm_offset_t)(addr + len)))
140 * Nominal kernel memory access - check access via kernel_map.
142 if ((vm_offset_t)addr + len > kernel_map.max_offset ||
143 (vm_offset_t)addr + len < (vm_offset_t)addr) {
147 saddr = trunc_page((vm_offset_t)addr);
148 eaddr = round_page((vm_offset_t)addr + len);
149 rv = vm_map_check_protection(&kernel_map, saddr, eaddr, prot, FALSE);
158 useracc(c_caddr_t addr, int len, int rw)
163 vm_map_entry_t save_hint;
166 KASSERT((rw & (~VM_PROT_ALL)) == 0,
167 ("illegal ``rw'' argument to useracc (%x)\n", rw));
170 * XXX - check separately to disallow access to user area and user
171 * page tables - they are in the map.
173 wrap = (vm_offset_t)addr + len;
174 if (wrap > VM_MAX_USER_ADDRESS || wrap < (vm_offset_t)addr) {
177 map = &curproc->p_vmspace->vm_map;
178 vm_map_lock_read(map);
180 * We save the map hint, and restore it. Useracc appears to distort
181 * the map hint unnecessarily.
183 save_hint = map->hint;
184 rv = vm_map_check_protection(map, trunc_page((vm_offset_t)addr),
185 round_page(wrap), prot, TRUE);
186 map->hint = save_hint;
187 vm_map_unlock_read(map);
196 vslock(caddr_t addr, u_int len)
199 vm_map_wire(&curproc->p_vmspace->vm_map,
200 trunc_page((vm_offset_t)addr),
201 round_page((vm_offset_t)addr + len), 0);
209 vsunlock(caddr_t addr, u_int len)
212 vm_map_wire(&curproc->p_vmspace->vm_map,
213 trunc_page((vm_offset_t)addr),
214 round_page((vm_offset_t)addr + len),
220 * Implement fork's actions on an address space.
221 * Here we arrange for the address space to be copied or referenced,
222 * allocate a user struct (pcb and kernel stack), then call the
223 * machine-dependent layer to fill those in and make the new process
224 * ready to run. The new process is set up so that it returns directly
225 * to user mode to avoid stack copying and relocation problems.
230 vm_fork(struct proc *p1, struct proc *p2, int flags)
232 if ((flags & RFPROC) == 0) {
234 * Divorce the memory, if it is shared, essentially
235 * this changes shared memory amongst threads, into
238 if ((flags & RFMEM) == 0) {
239 if (p1->p_vmspace->vm_sysref.refcnt > 1) {
243 cpu_fork(ONLY_LWP_IN_PROC(p1), NULL, flags);
248 vmspace_ref(p1->p_vmspace);
249 p2->p_vmspace = p1->p_vmspace;
252 while (vm_page_count_severe()) {
256 if ((flags & RFMEM) == 0) {
257 p2->p_vmspace = vmspace_fork(p1->p_vmspace);
259 pmap_pinit2(vmspace_pmap(p2->p_vmspace));
261 if (p1->p_vmspace->vm_shm)
269 * Set default limits for VM system. Call during proc0's initialization.
271 * Called from the low level boot code only.
274 vm_init_limits(struct proc *p)
279 * Set up the initial limits on process VM. Set the maximum resident
280 * set size to be half of (reasonably) available memory. Since this
281 * is a soft limit, it comes into effect only when the system is out
282 * of memory - half of main memory helps to favor smaller processes,
283 * and reduces thrashing of the object cache.
285 p->p_rlimit[RLIMIT_STACK].rlim_cur = dflssiz;
286 p->p_rlimit[RLIMIT_STACK].rlim_max = maxssiz;
287 p->p_rlimit[RLIMIT_DATA].rlim_cur = dfldsiz;
288 p->p_rlimit[RLIMIT_DATA].rlim_max = maxdsiz;
289 /* limit the limit to no less than 2MB */
290 rss_limit = max(vmstats.v_free_count, 512);
291 p->p_rlimit[RLIMIT_RSS].rlim_cur = ptoa(rss_limit);
292 p->p_rlimit[RLIMIT_RSS].rlim_max = RLIM_INFINITY;
296 * Faultin the specified process. Note that the process can be in any
297 * state. Just clear P_SWAPPEDOUT and call wakeup in case the process is
303 faultin(struct proc *p)
305 if (p->p_flags & P_SWAPPEDOUT) {
307 * The process is waiting in the kernel to return to user
308 * mode but cannot until P_SWAPPEDOUT gets cleared.
310 lwkt_gettoken(&p->p_token);
311 p->p_flags &= ~(P_SWAPPEDOUT | P_SWAPWAIT);
314 kprintf("swapping in %d (%s)\n", p->p_pid, p->p_comm);
317 lwkt_reltoken(&p->p_token);
322 * Kernel initialization eventually falls through to this function,
323 * which is process 0.
325 * This swapin algorithm attempts to swap-in processes only if there
326 * is enough space for them. Of course, if a process waits for a long
327 * time, it will be swapped in anyway.
329 struct scheduler_info {
334 static int scheduler_callback(struct proc *p, void *data);
337 scheduler(void *dummy)
339 struct scheduler_info info;
342 KKASSERT(!IN_CRITICAL_SECT(curthread));
344 scheduler_notify = 0;
346 * Don't try to swap anything in if we are low on memory.
348 if (vm_page_count_severe()) {
354 * Look for a good candidate to wake up
358 allproc_scan(scheduler_callback, &info);
361 * Nothing to do, back to sleep for at least 1/10 of a second. If
362 * we are woken up, immediately process the next request. If
363 * multiple requests have built up the first is processed
364 * immediately and the rest are staggered.
366 if ((p = info.pp) == NULL) {
367 tsleep(&proc0, 0, "nowork", hz / 10);
368 if (scheduler_notify == 0)
369 tsleep(&scheduler_notify, 0, "nowork", 0);
374 * Fault the selected process in, then wait for a short period of
377 * XXX we need a heuristic to get a measure of system stress and
378 * then adjust our stagger wakeup delay accordingly.
380 lwkt_gettoken(&proc_token);
384 lwkt_reltoken(&proc_token);
385 tsleep(&proc0, 0, "swapin", hz / 10);
390 * The caller must hold proc_token.
393 scheduler_callback(struct proc *p, void *data)
395 struct scheduler_info *info = data;
400 if (p->p_flags & P_SWAPWAIT) {
402 FOREACH_LWP_IN_PROC(lp, p) {
403 /* XXX lwp might need a different metric */
404 pri += lp->lwp_slptime;
406 pri += p->p_swtime - p->p_nice * 8;
409 * The more pages paged out while we were swapped,
410 * the more work we have to do to get up and running
411 * again and the lower our wakeup priority.
413 * Each second of sleep time is worth ~1MB
415 lwkt_gettoken(&p->p_vmspace->vm_map.token);
416 pgs = vmspace_resident_count(p->p_vmspace);
417 if (pgs < p->p_vmspace->vm_swrss) {
418 pri -= (p->p_vmspace->vm_swrss - pgs) /
419 (1024 * 1024 / PAGE_SIZE);
421 lwkt_reltoken(&p->p_vmspace->vm_map.token);
424 * If this process is higher priority and there is
425 * enough space, then select this process instead of
426 * the previous selection.
428 if (pri > info->ppri) {
446 if (scheduler_notify == 0) {
447 scheduler_notify = 1;
448 wakeup(&scheduler_notify);
454 #define swappable(p) \
455 (((p)->p_lock == 0) && \
456 ((p)->p_flags & (P_TRACED|P_SYSTEM|P_SWAPPEDOUT|P_WEXIT)) == 0)
460 * Swap_idle_threshold1 is the guaranteed swapped in time for a process
462 static int swap_idle_threshold1 = 15;
463 SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold1,
464 CTLFLAG_RW, &swap_idle_threshold1, 0, "Guaranteed process resident time (sec)");
467 * Swap_idle_threshold2 is the time that a process can be idle before
468 * it will be swapped out, if idle swapping is enabled. Default is
471 static int swap_idle_threshold2 = 60;
472 SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold2,
473 CTLFLAG_RW, &swap_idle_threshold2, 0, "Time (sec) a process can idle before being swapped");
476 * Swapout is driven by the pageout daemon. Very simple, we find eligible
477 * procs and mark them as being swapped out. This will cause the kernel
478 * to prefer to pageout those proc's pages first and the procs in question
479 * will not return to user mode until the swapper tells them they can.
481 * If any procs have been sleeping/stopped for at least maxslp seconds,
482 * they are swapped. Else, we swap the longest-sleeping or stopped process,
483 * if any, otherwise the longest-resident process.
486 static int swapout_procs_callback(struct proc *p, void *data);
492 swapout_procs(int action)
494 allproc_scan(swapout_procs_callback, &action);
498 * The caller must hold proc_token
501 swapout_procs_callback(struct proc *p, void *data)
505 int action = *(int *)data;
511 lwkt_gettoken(&p->p_token);
515 * We only consider active processes.
517 if (p->p_stat != SACTIVE && p->p_stat != SSTOP) {
518 lwkt_reltoken(&p->p_token);
522 FOREACH_LWP_IN_PROC(lp, p) {
524 * do not swap out a realtime process
526 if (RTP_PRIO_IS_REALTIME(lp->lwp_rtprio.type)) {
527 lwkt_reltoken(&p->p_token);
532 * Guarentee swap_idle_threshold time in memory
534 if (lp->lwp_slptime < swap_idle_threshold1) {
535 lwkt_reltoken(&p->p_token);
540 * If the system is under memory stress, or if we
541 * are swapping idle processes >= swap_idle_threshold2,
542 * then swap the process out.
544 if (((action & VM_SWAP_NORMAL) == 0) &&
545 (((action & VM_SWAP_IDLE) == 0) ||
546 (lp->lwp_slptime < swap_idle_threshold2))) {
547 lwkt_reltoken(&p->p_token);
551 if (minslp == -1 || lp->lwp_slptime < minslp)
552 minslp = lp->lwp_slptime;
556 * If the process has been asleep for awhile, swap
559 if ((action & VM_SWAP_NORMAL) ||
560 ((action & VM_SWAP_IDLE) &&
561 (minslp > swap_idle_threshold2))) {
566 * cleanup our reference
568 lwkt_reltoken(&p->p_token);
574 * The caller must hold proc_token and p->p_token
577 swapout(struct proc *p)
581 kprintf("swapping out %d (%s)\n", p->p_pid, p->p_comm);
586 * remember the process resident count
588 p->p_vmspace->vm_swrss = vmspace_resident_count(p->p_vmspace);
589 p->p_flags |= P_SWAPPEDOUT;
593 #endif /* !NO_SWAPPING */