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. Neither the name of the University nor the names of its contributors
17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * from: @(#)vm_glue.c 8.6 (Berkeley) 1/5/94
35 * Copyright (c) 1987, 1990 Carnegie-Mellon University.
36 * All rights reserved.
38 * Permission to use, copy, modify and distribute this software and
39 * its documentation is hereby granted, provided that both the copyright
40 * notice and this permission notice appear in all copies of the
41 * software, derivative works or modified versions, and any portions
42 * thereof, and that both notices appear in supporting documentation.
44 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
45 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
46 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
48 * Carnegie Mellon requests users of this software to return to
50 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
51 * School of Computer Science
52 * Carnegie Mellon University
53 * Pittsburgh PA 15213-3890
55 * any improvements or extensions that they make and grant Carnegie the
56 * rights to redistribute these changes.
59 #include <sys/cdefs.h>
60 __FBSDID("$FreeBSD$");
63 #include "opt_kstack_pages.h"
64 #include "opt_kstack_max_pages.h"
65 #include "opt_kstack_usage_prof.h"
67 #include <sys/param.h>
68 #include <sys/systm.h>
69 #include <sys/limits.h>
71 #include <sys/malloc.h>
72 #include <sys/mutex.h>
74 #include <sys/racct.h>
75 #include <sys/resourcevar.h>
76 #include <sys/rwlock.h>
77 #include <sys/sched.h>
78 #include <sys/sf_buf.h>
80 #include <sys/vmmeter.h>
83 #include <sys/sysctl.h>
84 #include <sys/_kstack_cache.h>
85 #include <sys/eventhandler.h>
86 #include <sys/kernel.h>
88 #include <sys/unistd.h>
91 #include <vm/vm_param.h>
93 #include <vm/vm_map.h>
94 #include <vm/vm_page.h>
95 #include <vm/vm_pageout.h>
96 #include <vm/vm_object.h>
97 #include <vm/vm_kern.h>
98 #include <vm/vm_extern.h>
99 #include <vm/vm_pager.h>
100 #include <vm/swap_pager.h>
102 #include <machine/cpu.h>
105 static int swapout(struct proc *);
106 static void swapclear(struct proc *);
107 static void vm_thread_swapin(struct thread *td);
108 static void vm_thread_swapout(struct thread *td);
114 * WARNING! This code calls vm_map_check_protection() which only checks
115 * the associated vm_map_entry range. It does not determine whether the
116 * contents of the memory is actually readable or writable. In most cases
117 * just checking the vm_map_entry is sufficient within the kernel's address
121 kernacc(addr, len, rw)
126 vm_offset_t saddr, eaddr;
129 KASSERT((rw & ~VM_PROT_ALL) == 0,
130 ("illegal ``rw'' argument to kernacc (%x)\n", rw));
132 if ((vm_offset_t)addr + len > kernel_map->max_offset ||
133 (vm_offset_t)addr + len < (vm_offset_t)addr)
137 saddr = trunc_page((vm_offset_t)addr);
138 eaddr = round_page((vm_offset_t)addr + len);
139 vm_map_lock_read(kernel_map);
140 rv = vm_map_check_protection(kernel_map, saddr, eaddr, prot);
141 vm_map_unlock_read(kernel_map);
148 * WARNING! This code calls vm_map_check_protection() which only checks
149 * the associated vm_map_entry range. It does not determine whether the
150 * contents of the memory is actually readable or writable. vmapbuf(),
151 * vm_fault_quick(), or copyin()/copout()/su*()/fu*() functions should be
152 * used in conjunction with this call.
155 useracc(addr, len, rw)
163 KASSERT((rw & ~VM_PROT_ALL) == 0,
164 ("illegal ``rw'' argument to useracc (%x)\n", rw));
166 map = &curproc->p_vmspace->vm_map;
167 if ((vm_offset_t)addr + len > vm_map_max(map) ||
168 (vm_offset_t)addr + len < (vm_offset_t)addr) {
171 vm_map_lock_read(map);
172 rv = vm_map_check_protection(map, trunc_page((vm_offset_t)addr),
173 round_page((vm_offset_t)addr + len), prot);
174 vm_map_unlock_read(map);
179 vslock(void *addr, size_t len)
181 vm_offset_t end, last, start;
185 last = (vm_offset_t)addr + len;
186 start = trunc_page((vm_offset_t)addr);
187 end = round_page(last);
188 if (last < (vm_offset_t)addr || end < (vm_offset_t)addr)
190 npages = atop(end - start);
191 if (npages > vm_page_max_wired)
197 * The limit for transient usage of wired pages should be
198 * larger than for "permanent" wired pages (mlock()).
200 * Also, the sysctl code, which is the only present user
201 * of vslock(), does a hard loop on EAGAIN.
203 if (npages + vm_cnt.v_wire_count > vm_page_max_wired)
206 error = vm_map_wire(&curproc->p_vmspace->vm_map, start, end,
207 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES);
209 * Return EFAULT on error to match copy{in,out}() behaviour
210 * rather than returning ENOMEM like mlock() would.
212 return (error == KERN_SUCCESS ? 0 : EFAULT);
216 vsunlock(void *addr, size_t len)
219 /* Rely on the parameter sanity checks performed by vslock(). */
220 (void)vm_map_unwire(&curproc->p_vmspace->vm_map,
221 trunc_page((vm_offset_t)addr), round_page((vm_offset_t)addr + len),
222 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES);
226 * Pin the page contained within the given object at the given offset. If the
227 * page is not resident, allocate and load it using the given object's pager.
228 * Return the pinned page if successful; otherwise, return NULL.
231 vm_imgact_hold_page(vm_object_t object, vm_ooffset_t offset)
237 VM_OBJECT_WLOCK(object);
238 pindex = OFF_TO_IDX(offset);
239 m = vm_page_grab(object, pindex, VM_ALLOC_NORMAL | VM_ALLOC_NOBUSY);
240 if (m->valid != VM_PAGE_BITS_ALL) {
242 rv = vm_pager_get_pages(object, &m, 1, NULL, NULL);
243 if (rv != VM_PAGER_OK) {
257 VM_OBJECT_WUNLOCK(object);
262 * Return a CPU private mapping to the page at the given offset within the
263 * given object. The page is pinned before it is mapped.
266 vm_imgact_map_page(vm_object_t object, vm_ooffset_t offset)
270 m = vm_imgact_hold_page(object, offset);
274 return (sf_buf_alloc(m, SFB_CPUPRIVATE));
278 * Destroy the given CPU private mapping and unpin the page that it mapped.
281 vm_imgact_unmap_page(struct sf_buf *sf)
294 vm_sync_icache(vm_map_t map, vm_offset_t va, vm_offset_t sz)
297 pmap_sync_icache(map->pmap, va, sz);
300 struct kstack_cache_entry *kstack_cache;
301 static int kstack_cache_size = 128;
303 static struct mtx kstack_cache_mtx;
304 MTX_SYSINIT(kstack_cache, &kstack_cache_mtx, "kstkch", MTX_DEF);
306 SYSCTL_INT(_vm, OID_AUTO, kstack_cache_size, CTLFLAG_RW, &kstack_cache_size, 0,
308 SYSCTL_INT(_vm, OID_AUTO, kstacks, CTLFLAG_RD, &kstacks, 0,
311 #ifndef KSTACK_MAX_PAGES
312 #define KSTACK_MAX_PAGES 32
316 * Create the kernel stack (including pcb for i386) for a new thread.
317 * This routine directly affects the fork perf for a process and
318 * create performance for a thread.
321 vm_thread_new(struct thread *td, int pages)
325 vm_page_t ma[KSTACK_MAX_PAGES];
326 struct kstack_cache_entry *ks_ce;
331 pages = kstack_pages;
332 else if (pages > KSTACK_MAX_PAGES)
333 pages = KSTACK_MAX_PAGES;
335 if (pages == kstack_pages) {
336 mtx_lock(&kstack_cache_mtx);
337 if (kstack_cache != NULL) {
338 ks_ce = kstack_cache;
339 kstack_cache = ks_ce->next_ks_entry;
340 mtx_unlock(&kstack_cache_mtx);
342 td->td_kstack_obj = ks_ce->ksobj;
343 td->td_kstack = (vm_offset_t)ks_ce;
344 td->td_kstack_pages = kstack_pages;
347 mtx_unlock(&kstack_cache_mtx);
351 * Allocate an object for the kstack.
353 ksobj = vm_object_allocate(OBJT_DEFAULT, pages);
356 * Get a kernel virtual address for this thread's kstack.
358 #if defined(__mips__)
360 * We need to align the kstack's mapped address to fit within
361 * a single TLB entry.
363 if (vmem_xalloc(kernel_arena, (pages + KSTACK_GUARD_PAGES) * PAGE_SIZE,
364 PAGE_SIZE * 2, 0, 0, VMEM_ADDR_MIN, VMEM_ADDR_MAX,
365 M_BESTFIT | M_NOWAIT, &ks)) {
369 ks = kva_alloc((pages + KSTACK_GUARD_PAGES) * PAGE_SIZE);
372 printf("vm_thread_new: kstack allocation failed\n");
373 vm_object_deallocate(ksobj);
377 atomic_add_int(&kstacks, 1);
378 if (KSTACK_GUARD_PAGES != 0) {
379 pmap_qremove(ks, KSTACK_GUARD_PAGES);
380 ks += KSTACK_GUARD_PAGES * PAGE_SIZE;
382 td->td_kstack_obj = ksobj;
385 * Knowing the number of pages allocated is useful when you
386 * want to deallocate them.
388 td->td_kstack_pages = pages;
390 * For the length of the stack, link in a real page of ram for each
393 VM_OBJECT_WLOCK(ksobj);
394 vm_page_grab_pages(ksobj, 0, VM_ALLOC_NORMAL | VM_ALLOC_NOBUSY |
395 VM_ALLOC_WIRED, ma, pages);
396 for (i = 0; i < pages; i++)
397 ma[i]->valid = VM_PAGE_BITS_ALL;
398 VM_OBJECT_WUNLOCK(ksobj);
399 pmap_qenter(ks, ma, pages);
404 vm_thread_stack_dispose(vm_object_t ksobj, vm_offset_t ks, int pages)
409 atomic_add_int(&kstacks, -1);
410 pmap_qremove(ks, pages);
411 VM_OBJECT_WLOCK(ksobj);
412 for (i = 0; i < pages; i++) {
413 m = vm_page_lookup(ksobj, i);
415 panic("vm_thread_dispose: kstack already missing?");
417 vm_page_unwire(m, PQ_NONE);
421 VM_OBJECT_WUNLOCK(ksobj);
422 vm_object_deallocate(ksobj);
423 kva_free(ks - (KSTACK_GUARD_PAGES * PAGE_SIZE),
424 (pages + KSTACK_GUARD_PAGES) * PAGE_SIZE);
428 * Dispose of a thread's kernel stack.
431 vm_thread_dispose(struct thread *td)
435 struct kstack_cache_entry *ks_ce;
438 pages = td->td_kstack_pages;
439 ksobj = td->td_kstack_obj;
442 td->td_kstack_pages = 0;
443 if (pages == kstack_pages && kstacks <= kstack_cache_size) {
444 ks_ce = (struct kstack_cache_entry *)ks;
445 ks_ce->ksobj = ksobj;
446 mtx_lock(&kstack_cache_mtx);
447 ks_ce->next_ks_entry = kstack_cache;
448 kstack_cache = ks_ce;
449 mtx_unlock(&kstack_cache_mtx);
452 vm_thread_stack_dispose(ksobj, ks, pages);
456 vm_thread_stack_lowmem(void *nulll)
458 struct kstack_cache_entry *ks_ce, *ks_ce1;
460 mtx_lock(&kstack_cache_mtx);
461 ks_ce = kstack_cache;
463 mtx_unlock(&kstack_cache_mtx);
465 while (ks_ce != NULL) {
467 ks_ce = ks_ce->next_ks_entry;
469 vm_thread_stack_dispose(ks_ce1->ksobj, (vm_offset_t)ks_ce1,
475 kstack_cache_init(void *nulll)
478 EVENTHANDLER_REGISTER(vm_lowmem, vm_thread_stack_lowmem, NULL,
479 EVENTHANDLER_PRI_ANY);
482 SYSINIT(vm_kstacks, SI_SUB_KTHREAD_INIT, SI_ORDER_ANY, kstack_cache_init, NULL);
484 #ifdef KSTACK_USAGE_PROF
486 * Track maximum stack used by a thread in kernel.
488 static int max_kstack_used;
490 SYSCTL_INT(_debug, OID_AUTO, max_kstack_used, CTLFLAG_RD,
492 "Maxiumum stack depth used by a thread in kernel");
495 intr_prof_stack_use(struct thread *td, struct trapframe *frame)
497 vm_offset_t stack_top;
502 * Testing for interrupted kernel mode isn't strictly
503 * needed. It optimizes the execution, since interrupts from
504 * usermode will have only the trap frame on the stack.
506 if (TRAPF_USERMODE(frame))
509 stack_top = td->td_kstack + td->td_kstack_pages * PAGE_SIZE;
510 current = (vm_offset_t)(uintptr_t)&stack_top;
513 * Try to detect if interrupt is using kernel thread stack.
514 * Hardware could use a dedicated stack for interrupt handling.
516 if (stack_top <= current || current < td->td_kstack)
519 used = stack_top - current;
521 prev_used = max_kstack_used;
522 if (prev_used >= used)
524 if (atomic_cmpset_int(&max_kstack_used, prev_used, used))
528 #endif /* KSTACK_USAGE_PROF */
532 * Allow a thread's kernel stack to be paged out.
535 vm_thread_swapout(struct thread *td)
541 cpu_thread_swapout(td);
542 pages = td->td_kstack_pages;
543 ksobj = td->td_kstack_obj;
544 pmap_qremove(td->td_kstack, pages);
545 VM_OBJECT_WLOCK(ksobj);
546 for (i = 0; i < pages; i++) {
547 m = vm_page_lookup(ksobj, i);
549 panic("vm_thread_swapout: kstack already missing?");
552 vm_page_unwire(m, PQ_INACTIVE);
555 VM_OBJECT_WUNLOCK(ksobj);
559 * Bring the kernel stack for a specified thread back in.
562 vm_thread_swapin(struct thread *td)
565 vm_page_t ma[KSTACK_MAX_PAGES];
568 pages = td->td_kstack_pages;
569 ksobj = td->td_kstack_obj;
570 VM_OBJECT_WLOCK(ksobj);
571 vm_page_grab_pages(ksobj, 0, VM_ALLOC_NORMAL | VM_ALLOC_WIRED, ma,
573 for (int i = 0; i < pages;) {
576 vm_page_assert_xbusied(ma[i]);
577 if (ma[i]->valid == VM_PAGE_BITS_ALL) {
578 vm_page_xunbusy(ma[i]);
582 vm_object_pip_add(ksobj, 1);
583 for (j = i + 1; j < pages; j++)
584 if (ma[j]->valid == VM_PAGE_BITS_ALL)
586 rv = vm_pager_has_page(ksobj, ma[i]->pindex, NULL, &a);
587 KASSERT(rv == 1, ("%s: missing page %p", __func__, ma[i]));
588 count = min(a + 1, j - i);
589 rv = vm_pager_get_pages(ksobj, ma + i, count, NULL, NULL);
590 KASSERT(rv == VM_PAGER_OK, ("%s: cannot get kstack for proc %d",
591 __func__, td->td_proc->p_pid));
592 vm_object_pip_wakeup(ksobj);
593 for (j = i; j < i + count; j++)
594 vm_page_xunbusy(ma[j]);
597 VM_OBJECT_WUNLOCK(ksobj);
598 pmap_qenter(td->td_kstack, ma, pages);
599 cpu_thread_swapin(td);
601 #endif /* !NO_SWAPPING */
604 * Implement fork's actions on an address space.
605 * Here we arrange for the address space to be copied or referenced,
606 * allocate a user struct (pcb and kernel stack), then call the
607 * machine-dependent layer to fill those in and make the new process
608 * ready to run. The new process is set up so that it returns directly
609 * to user mode to avoid stack copying and relocation problems.
612 vm_forkproc(td, p2, td2, vm2, flags)
619 struct proc *p1 = td->td_proc;
622 if ((flags & RFPROC) == 0) {
624 * Divorce the memory, if it is shared, essentially
625 * this changes shared memory amongst threads, into
628 if ((flags & RFMEM) == 0) {
629 if (p1->p_vmspace->vm_refcnt > 1) {
630 error = vmspace_unshare(p1);
635 cpu_fork(td, p2, td2, flags);
640 p2->p_vmspace = p1->p_vmspace;
641 atomic_add_int(&p1->p_vmspace->vm_refcnt, 1);
644 while (vm_page_count_severe()) {
648 if ((flags & RFMEM) == 0) {
650 if (p1->p_vmspace->vm_shm)
655 * cpu_fork will copy and update the pcb, set up the kernel stack,
656 * and make the child ready to run.
658 cpu_fork(td, p2, td2, flags);
663 * Called after process has been wait(2)'ed upon and is being reaped.
664 * The idea is to reclaim resources that we could not reclaim while
665 * the process was still executing.
672 vmspace_exitfree(p); /* and clean-out the vmspace */
681 PROC_LOCK_ASSERT(p, MA_OWNED);
682 if ((p->p_flag & P_INMEM) == 0)
683 panic("faultin: proc swapped out with NO_SWAPPING!");
684 #else /* !NO_SWAPPING */
687 PROC_LOCK_ASSERT(p, MA_OWNED);
689 * If another process is swapping in this process,
690 * just wait until it finishes.
692 if (p->p_flag & P_SWAPPINGIN) {
693 while (p->p_flag & P_SWAPPINGIN)
694 msleep(&p->p_flag, &p->p_mtx, PVM, "faultin", 0);
697 if ((p->p_flag & P_INMEM) == 0) {
699 * Don't let another thread swap process p out while we are
700 * busy swapping it in.
703 p->p_flag |= P_SWAPPINGIN;
707 * We hold no lock here because the list of threads
708 * can not change while all threads in the process are
711 FOREACH_THREAD_IN_PROC(p, td)
712 vm_thread_swapin(td);
719 /* Allow other threads to swap p out now. */
722 #endif /* NO_SWAPPING */
726 * This swapin algorithm attempts to swap-in processes only if there
727 * is enough space for them. Of course, if a process waits for a long
728 * time, it will be swapped in anyway.
742 if (vm_page_count_min()) {
749 sx_slock(&allproc_lock);
750 FOREACH_PROC_IN_SYSTEM(p) {
752 if (p->p_state == PRS_NEW ||
753 p->p_flag & (P_SWAPPINGOUT | P_SWAPPINGIN | P_INMEM)) {
757 swtime = (ticks - p->p_swtick) / hz;
758 FOREACH_THREAD_IN_PROC(p, td) {
760 * An otherwise runnable thread of a process
761 * swapped out has only the TDI_SWAPPED bit set.
765 if (td->td_inhibitors == TDI_SWAPPED) {
766 slptime = (ticks - td->td_slptick) / hz;
767 pri = swtime + slptime;
768 if ((td->td_flags & TDF_SWAPINREQ) == 0)
769 pri -= p->p_nice * 8;
771 * if this thread is higher priority
772 * and there is enough space, then select
773 * this process instead of the previous
785 sx_sunlock(&allproc_lock);
788 * Nothing to do, back to sleep.
790 if ((p = pp) == NULL) {
791 tsleep(&proc0, PVM, "swapin", MAXSLP * hz / 2);
797 * Another process may be bringing or may have already
798 * brought this process in while we traverse all threads.
799 * Or, this process may even be being swapped out again.
801 if (p->p_flag & (P_INMEM | P_SWAPPINGOUT | P_SWAPPINGIN)) {
807 * We would like to bring someone in. (only if there is space).
808 * [What checks the space? ]
825 * Swap_idle_threshold1 is the guaranteed swapped in time for a process
827 static int swap_idle_threshold1 = 2;
828 SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold1, CTLFLAG_RW,
829 &swap_idle_threshold1, 0, "Guaranteed swapped in time for a process");
832 * Swap_idle_threshold2 is the time that a process can be idle before
833 * it will be swapped out, if idle swapping is enabled.
835 static int swap_idle_threshold2 = 10;
836 SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold2, CTLFLAG_RW,
837 &swap_idle_threshold2, 0, "Time before a process will be swapped out");
840 * First, if any processes have been sleeping or stopped for at least
841 * "swap_idle_threshold1" seconds, they are swapped out. If, however,
842 * no such processes exist, then the longest-sleeping or stopped
843 * process is swapped out. Finally, and only as a last resort, if
844 * there are no sleeping or stopped processes, the longest-resident
845 * process is swapped out.
848 swapout_procs(action)
856 sx_slock(&allproc_lock);
857 FOREACH_PROC_IN_SYSTEM(p) {
859 int minslptime = 100000;
864 * Watch out for a process in
865 * creation. It may have no
866 * address space or lock yet.
868 if (p->p_state == PRS_NEW) {
873 * An aio daemon switches its
874 * address space while running.
875 * Perform a quick check whether
876 * a process has P_SYSTEM.
877 * Filter out exiting processes.
879 if ((p->p_flag & (P_SYSTEM | P_WEXIT)) != 0) {
885 sx_sunlock(&allproc_lock);
888 * Do not swapout a process that
889 * is waiting for VM data
890 * structures as there is a possible
891 * deadlock. Test this first as
894 * Lock the map until swapout
895 * finishes, or a thread of this
896 * process may attempt to alter
899 vm = vmspace_acquire_ref(p);
902 if (!vm_map_trylock(&vm->vm_map))
906 if (p->p_lock != 1 || (p->p_flag & (P_STOPPED_SINGLE |
907 P_TRACED | P_SYSTEM)) != 0)
911 * only aiod changes vmspace, however it will be
912 * skipped because of the if statement above checking
915 if ((p->p_flag & (P_INMEM|P_SWAPPINGOUT|P_SWAPPINGIN)) != P_INMEM)
918 switch (p->p_state) {
920 /* Don't swap out processes in any sort
921 * of 'special' state. */
926 * do not swapout a realtime process
927 * Check all the thread groups..
929 FOREACH_THREAD_IN_PROC(p, td) {
931 if (PRI_IS_REALTIME(td->td_pri_class)) {
935 slptime = (ticks - td->td_slptick) / hz;
937 * Guarantee swap_idle_threshold1
940 if (slptime < swap_idle_threshold1) {
946 * Do not swapout a process if it is
947 * waiting on a critical event of some
948 * kind or there is a thread whose
949 * pageable memory may be accessed.
951 * This could be refined to support
952 * swapping out a thread.
954 if (!thread_safetoswapout(td)) {
959 * If the system is under memory stress,
960 * or if we are swapping
961 * idle processes >= swap_idle_threshold2,
962 * then swap the process out.
964 if (((action & VM_SWAP_NORMAL) == 0) &&
965 (((action & VM_SWAP_IDLE) == 0) ||
966 (slptime < swap_idle_threshold2))) {
971 if (minslptime > slptime)
972 minslptime = slptime;
977 * If the pageout daemon didn't free enough pages,
978 * or if this process is idle and the system is
979 * configured to swap proactively, swap it out.
981 if ((action & VM_SWAP_NORMAL) ||
982 ((action & VM_SWAP_IDLE) &&
983 (minslptime > swap_idle_threshold2))) {
988 vm_map_unlock(&vm->vm_map);
995 vm_map_unlock(&vm->vm_map);
999 sx_slock(&allproc_lock);
1002 sx_sunlock(&allproc_lock);
1004 * If we swapped something out, and another process needed memory,
1005 * then wakeup the sched process.
1017 PROC_LOCK_ASSERT(p, MA_OWNED);
1019 FOREACH_THREAD_IN_PROC(p, td) {
1021 td->td_flags |= TDF_INMEM;
1022 td->td_flags &= ~TDF_SWAPINREQ;
1025 if (setrunnable(td)) {
1028 * XXX: We just cleared TDI_SWAPPED
1029 * above and set TDF_INMEM, so this
1030 * should never happen.
1032 panic("not waking up swapper");
1037 p->p_flag &= ~(P_SWAPPINGIN|P_SWAPPINGOUT);
1038 p->p_flag |= P_INMEM;
1047 PROC_LOCK_ASSERT(p, MA_OWNED);
1048 #if defined(SWAP_DEBUG)
1049 printf("swapping out %d\n", p->p_pid);
1053 * The states of this process and its threads may have changed
1054 * by now. Assuming that there is only one pageout daemon thread,
1055 * this process should still be in memory.
1057 KASSERT((p->p_flag & (P_INMEM|P_SWAPPINGOUT|P_SWAPPINGIN)) == P_INMEM,
1058 ("swapout: lost a swapout race?"));
1061 * remember the process resident count
1063 p->p_vmspace->vm_swrss = vmspace_resident_count(p->p_vmspace);
1065 * Check and mark all threads before we proceed.
1067 p->p_flag &= ~P_INMEM;
1068 p->p_flag |= P_SWAPPINGOUT;
1069 FOREACH_THREAD_IN_PROC(p, td) {
1071 if (!thread_safetoswapout(td)) {
1076 td->td_flags &= ~TDF_INMEM;
1080 td = FIRST_THREAD_IN_PROC(p);
1081 ++td->td_ru.ru_nswap;
1085 * This list is stable because all threads are now prevented from
1086 * running. The list is only modified in the context of a running
1087 * thread in this process.
1089 FOREACH_THREAD_IN_PROC(p, td)
1090 vm_thread_swapout(td);
1093 p->p_flag &= ~P_SWAPPINGOUT;
1094 p->p_swtick = ticks;
1097 #endif /* !NO_SWAPPING */