2 * Copyright (c) 1991, 1993
3 * The Regents of the University of California. All rights reserved.
5 * This code is derived from software contributed to Berkeley by
6 * The Mach Operating System project at Carnegie-Mellon University.
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. All advertising materials mentioning features or use of this software
17 * must display the following acknowledgement:
18 * This product includes software developed by the University of
19 * California, Berkeley and its contributors.
20 * 4. Neither the name of the University nor the names of its contributors
21 * may be used to endorse or promote products derived from this software
22 * without specific prior written permission.
24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36 * from: @(#)vm_glue.c 8.6 (Berkeley) 1/5/94
39 * Copyright (c) 1987, 1990 Carnegie-Mellon University.
40 * All rights reserved.
42 * Permission to use, copy, modify and distribute this software and
43 * its documentation is hereby granted, provided that both the copyright
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45 * software, derivative works or modified versions, and any portions
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48 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
49 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
50 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
52 * Carnegie Mellon requests users of this software to return to
54 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
55 * School of Computer Science
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59 * any improvements or extensions that they make and grant Carnegie the
60 * rights to redistribute these changes.
62 * $FreeBSD: src/sys/vm/vm_glue.c,v 1.94.2.4 2003/01/13 22:51:17 dillon Exp $
63 * $DragonFly: src/sys/vm/vm_glue.c,v 1.53 2007/02/26 21:41:08 corecode Exp $
68 #include <sys/param.h>
69 #include <sys/systm.h>
71 #include <sys/resourcevar.h>
74 #include <sys/vmmeter.h>
75 #include <sys/sysctl.h>
77 #include <sys/kernel.h>
78 #include <sys/unistd.h>
80 #include <machine/limits.h>
83 #include <vm/vm_param.h>
86 #include <vm/vm_map.h>
87 #include <vm/vm_page.h>
88 #include <vm/vm_pageout.h>
89 #include <vm/vm_kern.h>
90 #include <vm/vm_extern.h>
93 #include <vm/vm_page2.h>
94 #include <sys/thread2.h>
97 * System initialization
99 * Note: proc0 from proc.h
102 static void vm_init_limits (void *);
103 SYSINIT(vm_limits, SI_SUB_VM_CONF, SI_ORDER_FIRST, vm_init_limits, &proc0)
106 * THIS MUST BE THE LAST INITIALIZATION ITEM!!!
108 * Note: run scheduling should be divorced from the vm system.
110 static void scheduler (void *);
111 SYSINIT(scheduler, SI_SUB_RUN_SCHEDULER, SI_ORDER_FIRST, scheduler, NULL)
115 static int swap_debug = 0;
116 SYSCTL_INT(_vm, OID_AUTO, swap_debug,
117 CTLFLAG_RW, &swap_debug, 0, "");
121 static int scheduler_notify;
123 static void swapout (struct proc *);
126 kernacc(c_caddr_t addr, int len, int rw)
129 vm_offset_t saddr, eaddr;
132 KASSERT((rw & (~VM_PROT_ALL)) == 0,
133 ("illegal ``rw'' argument to kernacc (%x)\n", rw));
136 * The globaldata space is not part of the kernel_map proper,
137 * check access separately.
139 if (is_globaldata_space((vm_offset_t)addr, (vm_offset_t)(addr + len)))
143 * Nominal kernel memory access - check access via kernel_map.
145 if ((vm_offset_t)addr + len > kernel_map.max_offset ||
146 (vm_offset_t)addr + len < (vm_offset_t)addr) {
150 saddr = trunc_page((vm_offset_t)addr);
151 eaddr = round_page((vm_offset_t)addr + len);
152 vm_map_lock_read(&kernel_map);
153 rv = vm_map_check_protection(&kernel_map, saddr, eaddr, prot);
154 vm_map_unlock_read(&kernel_map);
159 useracc(c_caddr_t addr, int len, int rw)
164 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 * XXX - VM_MAX_USER_ADDRESS is an end address, not a max. It was once
174 * only used (as an end address) in trap.c. Use it as an end address
175 * here too. This bogusness has spread. I just fixed where it was
176 * used as a max in vm_mmap.c.
178 if ((vm_offset_t) addr + len > /* XXX */ VM_MAX_USER_ADDRESS
179 || (vm_offset_t) addr + len < (vm_offset_t) addr) {
182 map = &curproc->p_vmspace->vm_map;
183 vm_map_lock_read(map);
185 * We save the map hint, and restore it. Useracc appears to distort
186 * the map hint unnecessarily.
188 save_hint = map->hint;
189 rv = vm_map_check_protection(map,
190 trunc_page((vm_offset_t)addr), round_page((vm_offset_t)addr + len), prot);
191 map->hint = save_hint;
192 vm_map_unlock_read(map);
198 vslock(caddr_t addr, u_int len)
201 vm_map_wire(&curproc->p_vmspace->vm_map,
202 trunc_page((vm_offset_t)addr),
203 round_page((vm_offset_t)addr + len), 0);
208 vsunlock(caddr_t addr, u_int len)
211 vm_map_wire(&curproc->p_vmspace->vm_map,
212 trunc_page((vm_offset_t)addr),
213 round_page((vm_offset_t)addr + len),
219 * Implement fork's actions on an address space.
220 * Here we arrange for the address space to be copied or referenced,
221 * allocate a user struct (pcb and kernel stack), then call the
222 * machine-dependent layer to fill those in and make the new process
223 * ready to run. The new process is set up so that it returns directly
224 * to user mode to avoid stack copying and relocation problems.
227 vm_fork(struct proc *p1, struct proc *p2, int flags)
229 if ((flags & RFPROC) == 0) {
231 * Divorce the memory, if it is shared, essentially
232 * this changes shared memory amongst threads, into
235 if ((flags & RFMEM) == 0) {
236 if (p1->p_vmspace->vm_refcnt > 1) {
240 cpu_fork(ONLY_LWP_IN_PROC(p1), NULL, flags);
245 p2->p_vmspace = p1->p_vmspace;
246 p1->p_vmspace->vm_refcnt++;
249 while (vm_page_count_severe()) {
253 if ((flags & RFMEM) == 0) {
254 p2->p_vmspace = vmspace_fork(p1->p_vmspace);
256 pmap_pinit2(vmspace_pmap(p2->p_vmspace));
258 if (p1->p_vmspace->vm_shm)
266 * Called after process has been wait(2)'ed apon and is being reaped.
267 * The idea is to reclaim resources that we could not reclaim while
268 * the process was still executing.
271 vm_waitproc(struct proc *p)
274 vmspace_exitfree(p); /* and clean-out the vmspace */
278 * Set default limits for VM system.
279 * Called for proc 0, and then inherited by all others.
281 * XXX should probably act directly on proc0.
284 vm_init_limits(void *udata)
286 struct proc *p = udata;
290 * Set up the initial limits on process VM. Set the maximum resident
291 * set size to be half of (reasonably) available memory. Since this
292 * is a soft limit, it comes into effect only when the system is out
293 * of memory - half of main memory helps to favor smaller processes,
294 * and reduces thrashing of the object cache.
296 p->p_rlimit[RLIMIT_STACK].rlim_cur = dflssiz;
297 p->p_rlimit[RLIMIT_STACK].rlim_max = maxssiz;
298 p->p_rlimit[RLIMIT_DATA].rlim_cur = dfldsiz;
299 p->p_rlimit[RLIMIT_DATA].rlim_max = maxdsiz;
300 /* limit the limit to no less than 2MB */
301 rss_limit = max(vmstats.v_free_count, 512);
302 p->p_rlimit[RLIMIT_RSS].rlim_cur = ptoa(rss_limit);
303 p->p_rlimit[RLIMIT_RSS].rlim_max = RLIM_INFINITY;
307 * Faultin the specified process. Note that the process can be in any
308 * state. Just clear P_SWAPPEDOUT and call wakeup in case the process is
312 faultin(struct proc *p)
314 if (p->p_flag & P_SWAPPEDOUT) {
316 * The process is waiting in the kernel to return to user
317 * mode but cannot until P_SWAPPEDOUT gets cleared.
320 p->p_flag &= ~(P_SWAPPEDOUT | P_SWAPWAIT);
323 kprintf("swapping in %d (%s)\n", p->p_pid, p->p_comm);
332 * Kernel initialization eventually falls through to this function,
333 * which is process 0.
335 * This swapin algorithm attempts to swap-in processes only if there
336 * is enough space for them. Of course, if a process waits for a long
337 * time, it will be swapped in anyway.
340 struct scheduler_info {
345 static int scheduler_callback(struct proc *p, void *data);
348 scheduler(void *dummy)
350 struct scheduler_info info;
353 KKASSERT(!IN_CRITICAL_SECT(curthread));
355 scheduler_notify = 0;
357 * Don't try to swap anything in if we are low on memory.
359 if (vm_page_count_min()) {
365 * Look for a good candidate to wake up
369 allproc_scan(scheduler_callback, &info);
372 * Nothing to do, back to sleep for at least 1/10 of a second. If
373 * we are woken up, immediately process the next request. If
374 * multiple requests have built up the first is processed
375 * immediately and the rest are staggered.
377 if ((p = info.pp) == NULL) {
378 tsleep(&proc0, 0, "nowork", hz / 10);
379 if (scheduler_notify == 0)
380 tsleep(&scheduler_notify, 0, "nowork", 0);
385 * Fault the selected process in, then wait for a short period of
388 * XXX we need a heuristic to get a measure of system stress and
389 * then adjust our stagger wakeup delay accordingly.
394 tsleep(&proc0, 0, "swapin", hz / 10);
399 scheduler_callback(struct proc *p, void *data)
401 struct scheduler_info *info = data;
406 if (p->p_flag & P_SWAPWAIT) {
408 FOREACH_LWP_IN_PROC(lp, p) {
409 /* XXX lwp might need a different metric */
410 pri += lp->lwp_slptime;
412 pri += p->p_swtime - p->p_nice * 8;
415 * The more pages paged out while we were swapped,
416 * the more work we have to do to get up and running
417 * again and the lower our wakeup priority.
419 * Each second of sleep time is worth ~1MB
421 pgs = vmspace_resident_count(p->p_vmspace);
422 if (pgs < p->p_vmspace->vm_swrss) {
423 pri -= (p->p_vmspace->vm_swrss - pgs) /
424 (1024 * 1024 / PAGE_SIZE);
428 * If this process is higher priority and there is
429 * enough space, then select this process instead of
430 * the previous selection.
432 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_flag & (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, "");
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, "");
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);
489 swapout_procs(int action)
491 allproc_scan(swapout_procs_callback, &action);
495 swapout_procs_callback(struct proc *p, void *data)
499 int action = *(int *)data;
508 * We only consider active processes.
510 if (p->p_stat != SACTIVE && p->p_stat != SSTOP)
513 FOREACH_LWP_IN_PROC(lp, p) {
515 * do not swap out a realtime process
517 if (RTP_PRIO_IS_REALTIME(lp->lwp_rtprio.type))
521 * Guarentee swap_idle_threshold time in memory
523 if (lp->lwp_slptime < swap_idle_threshold1)
527 * If the system is under memory stress, or if we
528 * are swapping idle processes >= swap_idle_threshold2,
529 * then swap the process out.
531 if (((action & VM_SWAP_NORMAL) == 0) &&
532 (((action & VM_SWAP_IDLE) == 0) ||
533 (lp->lwp_slptime < swap_idle_threshold2))) {
537 if (minslp == -1 || lp->lwp_slptime < minslp)
538 minslp = lp->lwp_slptime;
544 * If the process has been asleep for awhile, swap
547 if ((action & VM_SWAP_NORMAL) ||
548 ((action & VM_SWAP_IDLE) &&
549 (minslp > swap_idle_threshold2))) {
554 * cleanup our reference
562 swapout(struct proc *p)
566 kprintf("swapping out %d (%s)\n", p->p_pid, p->p_comm);
570 * remember the process resident count
572 p->p_vmspace->vm_swrss = vmspace_resident_count(p->p_vmspace);
573 p->p_flag |= P_SWAPPEDOUT;
577 #endif /* !NO_SWAPPING */