2 * SPDX-License-Identifier: (BSD-4-Clause AND MIT-CMU)
4 * Copyright (c) 1991 Regents of the University of California.
6 * Copyright (c) 1994 John S. Dyson
8 * Copyright (c) 1994 David Greenman
10 * Copyright (c) 2005 Yahoo! Technologies Norway AS
11 * All rights reserved.
13 * This code is derived from software contributed to Berkeley by
14 * The Mach Operating System project at Carnegie-Mellon University.
16 * Redistribution and use in source and binary forms, with or without
17 * modification, are permitted provided that the following conditions
19 * 1. Redistributions of source code must retain the above copyright
20 * notice, this list of conditions and the following disclaimer.
21 * 2. Redistributions in binary form must reproduce the above copyright
22 * notice, this list of conditions and the following disclaimer in the
23 * documentation and/or other materials provided with the distribution.
24 * 3. All advertising materials mentioning features or use of this software
25 * must display the following acknowledgement:
26 * This product includes software developed by the University of
27 * California, Berkeley and its contributors.
28 * 4. Neither the name of the University nor the names of its contributors
29 * may be used to endorse or promote products derived from this software
30 * without specific prior written permission.
32 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
33 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
34 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
35 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
36 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
37 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
38 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
39 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
40 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
41 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
44 * from: @(#)vm_pageout.c 7.4 (Berkeley) 5/7/91
47 * Copyright (c) 1987, 1990 Carnegie-Mellon University.
48 * All rights reserved.
50 * Authors: Avadis Tevanian, Jr., Michael Wayne Young
52 * Permission to use, copy, modify and distribute this software and
53 * its documentation is hereby granted, provided that both the copyright
54 * notice and this permission notice appear in all copies of the
55 * software, derivative works or modified versions, and any portions
56 * thereof, and that both notices appear in supporting documentation.
58 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
59 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
60 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
62 * Carnegie Mellon requests users of this software to return to
64 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
65 * School of Computer Science
66 * Carnegie Mellon University
67 * Pittsburgh PA 15213-3890
69 * any improvements or extensions that they make and grant Carnegie the
70 * rights to redistribute these changes.
73 #include <sys/cdefs.h>
74 __FBSDID("$FreeBSD$");
76 #include "opt_kstack_pages.h"
77 #include "opt_kstack_max_pages.h"
80 #include <sys/param.h>
81 #include <sys/systm.h>
82 #include <sys/limits.h>
83 #include <sys/kernel.h>
84 #include <sys/eventhandler.h>
86 #include <sys/mutex.h>
88 #include <sys/kthread.h>
90 #include <sys/mount.h>
91 #include <sys/racct.h>
92 #include <sys/resourcevar.h>
93 #include <sys/refcount.h>
94 #include <sys/sched.h>
96 #include <sys/signalvar.h>
99 #include <sys/vnode.h>
100 #include <sys/vmmeter.h>
101 #include <sys/rwlock.h>
103 #include <sys/sysctl.h>
106 #include <vm/vm_param.h>
107 #include <vm/vm_kern.h>
108 #include <vm/vm_object.h>
109 #include <vm/vm_page.h>
110 #include <vm/vm_map.h>
111 #include <vm/vm_pageout.h>
112 #include <vm/vm_pager.h>
113 #include <vm/vm_phys.h>
114 #include <vm/swap_pager.h>
115 #include <vm/vm_extern.h>
118 /* the kernel process "vm_daemon" */
119 static void vm_daemon(void);
120 static struct proc *vmproc;
122 static struct kproc_desc vm_kp = {
127 SYSINIT(vmdaemon, SI_SUB_KTHREAD_VM, SI_ORDER_FIRST, kproc_start, &vm_kp);
129 static int vm_swap_enabled = 1;
130 static int vm_swap_idle_enabled = 0;
132 SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled, CTLFLAG_RW,
134 "Enable entire process swapout");
135 SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled, CTLFLAG_RW,
136 &vm_swap_idle_enabled, 0,
137 "Allow swapout on idle criteria");
140 * Swap_idle_threshold1 is the guaranteed swapped in time for a process
142 static int swap_idle_threshold1 = 2;
143 SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold1, CTLFLAG_RW,
144 &swap_idle_threshold1, 0,
145 "Guaranteed swapped in time for a process");
148 * Swap_idle_threshold2 is the time that a process can be idle before
149 * it will be swapped out, if idle swapping is enabled.
151 static int swap_idle_threshold2 = 10;
152 SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold2, CTLFLAG_RW,
153 &swap_idle_threshold2, 0,
154 "Time before a process will be swapped out");
156 static int vm_pageout_req_swapout; /* XXX */
157 static int vm_daemon_needed;
158 static struct mtx vm_daemon_mtx;
159 /* Allow for use by vm_pageout before vm_daemon is initialized. */
160 MTX_SYSINIT(vm_daemon, &vm_daemon_mtx, "vm daemon", MTX_DEF);
162 static int swapped_cnt;
163 static int swap_inprogress; /* Pending swap-ins done outside swapper. */
164 static int last_swapin;
166 static void swapclear(struct proc *);
167 static int swapout(struct proc *);
168 static void vm_swapout_map_deactivate_pages(vm_map_t, long);
169 static void vm_swapout_object_deactivate(pmap_t, vm_object_t, long);
170 static void swapout_procs(int action);
171 static void vm_req_vmdaemon(int req);
172 static void vm_thread_swapout(struct thread *td);
175 vm_swapout_object_deactivate_page(pmap_t pmap, vm_page_t m, bool unmap)
179 * Ignore unreclaimable wired pages. Repeat the check after busying
180 * since a busy holder may wire the page.
182 if (vm_page_wired(m) || !vm_page_tryxbusy(m))
185 if (vm_page_wired(m) || !pmap_page_exists_quick(pmap, m)) {
189 if (!pmap_is_referenced(m)) {
190 if (!vm_page_active(m))
191 (void)vm_page_try_remove_all(m);
192 else if (unmap && vm_page_try_remove_all(m))
193 vm_page_deactivate(m);
199 * vm_swapout_object_deactivate
201 * Deactivate enough pages to satisfy the inactive target
204 * The object and map must be locked.
207 vm_swapout_object_deactivate(pmap_t pmap, vm_object_t first_object,
210 vm_object_t backing_object, object;
214 VM_OBJECT_ASSERT_LOCKED(first_object);
215 if ((first_object->flags & OBJ_FICTITIOUS) != 0)
217 for (object = first_object;; object = backing_object) {
218 if (pmap_resident_count(pmap) <= desired)
220 VM_OBJECT_ASSERT_LOCKED(object);
221 if ((object->flags & OBJ_UNMANAGED) != 0 ||
222 blockcount_read(&object->paging_in_progress) > 0)
226 if (object->shadow_count > 1)
230 * Scan the object's entire memory queue.
232 TAILQ_FOREACH(m, &object->memq, listq) {
233 if (pmap_resident_count(pmap) <= desired)
237 vm_swapout_object_deactivate_page(pmap, m, unmap);
239 if ((backing_object = object->backing_object) == NULL)
241 VM_OBJECT_RLOCK(backing_object);
242 if (object != first_object)
243 VM_OBJECT_RUNLOCK(object);
246 if (object != first_object)
247 VM_OBJECT_RUNLOCK(object);
251 * deactivate some number of pages in a map, try to do it fairly, but
252 * that is really hard to do.
255 vm_swapout_map_deactivate_pages(vm_map_t map, long desired)
258 vm_object_t obj, bigobj;
261 if (!vm_map_trylock_read(map))
268 * first, search out the biggest object, and try to free pages from
271 VM_MAP_ENTRY_FOREACH(tmpe, map) {
272 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) {
273 obj = tmpe->object.vm_object;
274 if (obj != NULL && VM_OBJECT_TRYRLOCK(obj)) {
275 if (obj->shadow_count <= 1 &&
277 bigobj->resident_page_count <
278 obj->resident_page_count)) {
280 VM_OBJECT_RUNLOCK(bigobj);
283 VM_OBJECT_RUNLOCK(obj);
286 if (tmpe->wired_count > 0)
287 nothingwired = FALSE;
290 if (bigobj != NULL) {
291 vm_swapout_object_deactivate(map->pmap, bigobj, desired);
292 VM_OBJECT_RUNLOCK(bigobj);
295 * Next, hunt around for other pages to deactivate. We actually
296 * do this search sort of wrong -- .text first is not the best idea.
298 VM_MAP_ENTRY_FOREACH(tmpe, map) {
299 if (pmap_resident_count(vm_map_pmap(map)) <= desired)
301 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) {
302 obj = tmpe->object.vm_object;
304 VM_OBJECT_RLOCK(obj);
305 vm_swapout_object_deactivate(map->pmap, obj,
307 VM_OBJECT_RUNLOCK(obj);
313 * Remove all mappings if a process is swapped out, this will free page
316 if (desired == 0 && nothingwired) {
317 pmap_remove(vm_map_pmap(map), vm_map_min(map),
321 vm_map_unlock_read(map);
327 #define VM_SWAP_NORMAL 1
328 #define VM_SWAP_IDLE 2
335 vm_req_vmdaemon(VM_SWAP_NORMAL);
339 * Idle process swapout -- run once per second when pagedaemons are
343 vm_swapout_run_idle(void)
347 if (!vm_swap_idle_enabled || time_second == lsec)
349 vm_req_vmdaemon(VM_SWAP_IDLE);
354 vm_req_vmdaemon(int req)
356 static int lastrun = 0;
358 mtx_lock(&vm_daemon_mtx);
359 vm_pageout_req_swapout |= req;
360 if ((ticks > (lastrun + hz)) || (ticks < lastrun)) {
361 wakeup(&vm_daemon_needed);
364 mtx_unlock(&vm_daemon_mtx);
370 struct rlimit rsslim;
374 int breakout, swapout_flags, tryagain, attempts;
376 uint64_t rsize, ravailable;
380 mtx_lock(&vm_daemon_mtx);
381 msleep(&vm_daemon_needed, &vm_daemon_mtx, PPAUSE, "psleep",
383 racct_enable ? hz : 0
388 swapout_flags = vm_pageout_req_swapout;
389 vm_pageout_req_swapout = 0;
390 mtx_unlock(&vm_daemon_mtx);
391 if (swapout_flags != 0) {
393 * Drain the per-CPU page queue batches as a deadlock
396 if ((swapout_flags & VM_SWAP_NORMAL) != 0)
397 vm_page_pqbatch_drain();
398 swapout_procs(swapout_flags);
402 * scan the processes for exceeding their rlimits or if
403 * process is swapped out -- deactivate pages
409 sx_slock(&allproc_lock);
410 FOREACH_PROC_IN_SYSTEM(p) {
411 vm_pindex_t limit, size;
414 * if this is a system process or if we have already
415 * looked at this process, skip it.
418 if (p->p_state != PRS_NORMAL ||
419 p->p_flag & (P_INEXEC | P_SYSTEM | P_WEXIT)) {
424 * if the process is in a non-running type state,
428 FOREACH_THREAD_IN_PROC(p, td) {
430 if (!TD_ON_RUNQ(td) &&
431 !TD_IS_RUNNING(td) &&
432 !TD_IS_SLEEPING(td) &&
433 !TD_IS_SUSPENDED(td)) {
447 lim_rlimit_proc(p, RLIMIT_RSS, &rsslim);
449 qmin(rsslim.rlim_cur, rsslim.rlim_max));
452 * let processes that are swapped out really be
453 * swapped out set the limit to nothing (will force a
456 if ((p->p_flag & P_INMEM) == 0)
458 vm = vmspace_acquire_ref(p);
465 sx_sunlock(&allproc_lock);
467 size = vmspace_resident_count(vm);
469 vm_swapout_map_deactivate_pages(
471 size = vmspace_resident_count(vm);
475 rsize = IDX_TO_OFF(size);
477 if (p->p_state == PRS_NORMAL)
478 racct_set(p, RACCT_RSS, rsize);
479 ravailable = racct_get_available(p, RACCT_RSS);
481 if (rsize > ravailable) {
483 * Don't be overly aggressive; this
484 * might be an innocent process,
485 * and the limit could've been exceeded
486 * by some memory hog. Don't try
487 * to deactivate more than 1/4th
488 * of process' resident set size.
491 if (ravailable < rsize -
497 vm_swapout_map_deactivate_pages(
499 OFF_TO_IDX(ravailable));
500 /* Update RSS usage after paging out. */
501 size = vmspace_resident_count(vm);
502 rsize = IDX_TO_OFF(size);
504 if (p->p_state == PRS_NORMAL)
505 racct_set(p, RACCT_RSS, rsize);
507 if (rsize > ravailable)
513 sx_slock(&allproc_lock);
516 sx_sunlock(&allproc_lock);
517 if (tryagain != 0 && attempts <= 10) {
525 * Allow a thread's kernel stack to be paged out.
528 vm_thread_swapout(struct thread *td)
535 cpu_thread_swapout(td);
536 kaddr = td->td_kstack;
537 pages = td->td_kstack_pages;
538 pindex = atop(kaddr - VM_MIN_KERNEL_ADDRESS);
539 pmap_qremove(kaddr, pages);
540 VM_OBJECT_WLOCK(kstack_object);
541 for (i = 0; i < pages; i++) {
542 m = vm_page_lookup(kstack_object, pindex + i);
544 panic("vm_thread_swapout: kstack already missing?");
546 vm_page_xunbusy_unchecked(m);
547 vm_page_unwire(m, PQ_LAUNDRY);
549 VM_OBJECT_WUNLOCK(kstack_object);
553 * Bring the kernel stack for a specified thread back in.
556 vm_thread_swapin(struct thread *td, int oom_alloc)
558 vm_page_t ma[KSTACK_MAX_PAGES];
560 int a, count, i, j, pages, rv;
562 kaddr = td->td_kstack;
563 pages = td->td_kstack_pages;
564 vm_thread_stack_back(td->td_domain.dr_policy, kaddr, ma, pages,
566 for (i = 0; i < pages;) {
567 vm_page_assert_xbusied(ma[i]);
568 if (vm_page_all_valid(ma[i])) {
572 vm_object_pip_add(kstack_object, 1);
573 for (j = i + 1; j < pages; j++)
574 if (vm_page_all_valid(ma[j]))
576 VM_OBJECT_WLOCK(kstack_object);
577 rv = vm_pager_has_page(kstack_object, ma[i]->pindex, NULL, &a);
578 VM_OBJECT_WUNLOCK(kstack_object);
579 KASSERT(rv == 1, ("%s: missing page %p", __func__, ma[i]));
580 count = min(a + 1, j - i);
581 rv = vm_pager_get_pages(kstack_object, ma + i, count, NULL, NULL);
582 KASSERT(rv == VM_PAGER_OK, ("%s: cannot get kstack for proc %d",
583 __func__, td->td_proc->p_pid));
584 vm_object_pip_wakeup(kstack_object);
587 pmap_qenter(kaddr, ma, pages);
588 cpu_thread_swapin(td);
592 faultin(struct proc *p)
597 PROC_LOCK_ASSERT(p, MA_OWNED);
600 * If another process is swapping in this process,
601 * just wait until it finishes.
603 if (p->p_flag & P_SWAPPINGIN) {
604 while (p->p_flag & P_SWAPPINGIN)
605 msleep(&p->p_flag, &p->p_mtx, PVM, "faultin", 0);
609 if ((p->p_flag & P_INMEM) == 0) {
610 oom_alloc = (p->p_flag & P_WKILLED) != 0 ? VM_ALLOC_SYSTEM :
614 * Don't let another thread swap process p out while we are
615 * busy swapping it in.
618 p->p_flag |= P_SWAPPINGIN;
620 sx_xlock(&allproc_lock);
621 MPASS(swapped_cnt > 0);
623 if (curthread != &thread0)
625 sx_xunlock(&allproc_lock);
628 * We hold no lock here because the list of threads
629 * can not change while all threads in the process are
632 FOREACH_THREAD_IN_PROC(p, td)
633 vm_thread_swapin(td, oom_alloc);
635 if (curthread != &thread0) {
636 sx_xlock(&allproc_lock);
637 MPASS(swap_inprogress > 0);
640 sx_xunlock(&allproc_lock);
646 /* Allow other threads to swap p out now. */
653 * This swapin algorithm attempts to swap-in processes only if there
654 * is enough space for them. Of course, if a process waits for a long
655 * time, it will be swapped in anyway.
659 swapper_selector(bool wkilled_only)
661 struct proc *p, *res;
663 int ppri, pri, slptime, swtime;
665 sx_assert(&allproc_lock, SA_SLOCKED);
666 if (swapped_cnt == 0)
670 FOREACH_PROC_IN_SYSTEM(p) {
672 if (p->p_state == PRS_NEW || (p->p_flag & (P_SWAPPINGOUT |
673 P_SWAPPINGIN | P_INMEM)) != 0) {
677 if (p->p_state == PRS_NORMAL && (p->p_flag & P_WKILLED) != 0) {
679 * A swapped-out process might have mapped a
680 * large portion of the system's pages as
681 * anonymous memory. There is no other way to
682 * release the memory other than to kill the
683 * process, for which we need to swap it in.
691 swtime = (ticks - p->p_swtick) / hz;
692 FOREACH_THREAD_IN_PROC(p, td) {
694 * An otherwise runnable thread of a process
695 * swapped out has only the TDI_SWAPPED bit set.
698 if (td->td_inhibitors == TDI_SWAPPED) {
699 slptime = (ticks - td->td_slptick) / hz;
700 pri = swtime + slptime;
701 if ((td->td_flags & TDF_SWAPINREQ) == 0)
702 pri -= p->p_nice * 8;
704 * if this thread is higher priority
705 * and there is enough space, then select
706 * this process instead of the previous
724 #define SWAPIN_INTERVAL (MAXSLP * hz / 2)
727 * Limit swapper to swap in one non-WKILLED process in MAXSLP/2
728 * interval, assuming that there is:
729 * - at least one domain that is not suffering from a shortage of free memory;
730 * - no parallel swap-ins;
731 * - no other swap-ins in the current SWAPIN_INTERVAL.
734 swapper_wkilled_only(void)
737 return (vm_page_count_min_set(&all_domains) || swap_inprogress > 0 ||
738 (u_int)(ticks - last_swapin) < SWAPIN_INTERVAL);
747 sx_slock(&allproc_lock);
748 p = swapper_selector(swapper_wkilled_only());
749 sx_sunlock(&allproc_lock);
752 tsleep(&proc0, PVM, "swapin", SWAPIN_INTERVAL);
754 PROC_LOCK_ASSERT(p, MA_OWNED);
757 * Another process may be bringing or may have
758 * already brought this process in while we
759 * traverse all threads. Or, this process may
760 * have exited or even being swapped out
763 if (p->p_state == PRS_NORMAL && (p->p_flag & (P_INMEM |
764 P_SWAPPINGOUT | P_SWAPPINGIN)) == 0) {
773 * First, if any processes have been sleeping or stopped for at least
774 * "swap_idle_threshold1" seconds, they are swapped out. If, however,
775 * no such processes exist, then the longest-sleeping or stopped
776 * process is swapped out. Finally, and only as a last resort, if
777 * there are no sleeping or stopped processes, the longest-resident
778 * process is swapped out.
781 swapout_procs(int action)
786 bool didswap, doswap;
788 MPASS((action & (VM_SWAP_NORMAL | VM_SWAP_IDLE)) != 0);
791 sx_slock(&allproc_lock);
792 FOREACH_PROC_IN_SYSTEM(p) {
794 * Filter out not yet fully constructed processes. Do
795 * not swap out held processes. Avoid processes which
796 * are system, exiting, execing, traced, already swapped
797 * out or are in the process of being swapped in or out.
800 if (p->p_state != PRS_NORMAL || p->p_lock != 0 || (p->p_flag &
801 (P_SYSTEM | P_WEXIT | P_INEXEC | P_STOPPED_SINGLE |
802 P_TRACED | P_SWAPPINGOUT | P_SWAPPINGIN | P_INMEM)) !=
809 * Further consideration of this process for swap out
810 * requires iterating over its threads. We release
811 * allproc_lock here so that process creation and
812 * destruction are not blocked while we iterate.
814 * To later reacquire allproc_lock and resume
815 * iteration over the allproc list, we will first have
816 * to release the lock on the process. We place a
817 * hold on the process so that it remains in the
818 * allproc list while it is unlocked.
821 sx_sunlock(&allproc_lock);
824 * Do not swapout a realtime process.
825 * Guarantee swap_idle_threshold1 time in memory.
826 * If the system is under memory stress, or if we are
827 * swapping idle processes >= swap_idle_threshold2,
828 * then swap the process out.
831 FOREACH_THREAD_IN_PROC(p, td) {
833 slptime = (ticks - td->td_slptick) / hz;
834 if (PRI_IS_REALTIME(td->td_pri_class) ||
835 slptime < swap_idle_threshold1 ||
836 !thread_safetoswapout(td) ||
837 ((action & VM_SWAP_NORMAL) == 0 &&
838 slptime < swap_idle_threshold2))
844 if (doswap && swapout(p) == 0)
849 sx_xlock(&allproc_lock);
851 sx_downgrade(&allproc_lock);
853 sx_slock(&allproc_lock);
856 sx_sunlock(&allproc_lock);
859 * If we swapped something out, and another process needed memory,
860 * then wakeup the sched process.
867 swapclear(struct proc *p)
871 PROC_LOCK_ASSERT(p, MA_OWNED);
873 FOREACH_THREAD_IN_PROC(p, td) {
875 td->td_flags |= TDF_INMEM;
876 td->td_flags &= ~TDF_SWAPINREQ;
878 if (TD_CAN_RUN(td)) {
879 if (setrunnable(td, 0)) {
882 * XXX: We just cleared TDI_SWAPPED
883 * above and set TDF_INMEM, so this
884 * should never happen.
886 panic("not waking up swapper");
892 p->p_flag &= ~(P_SWAPPINGIN | P_SWAPPINGOUT);
893 p->p_flag |= P_INMEM;
897 swapout(struct proc *p)
901 PROC_LOCK_ASSERT(p, MA_OWNED);
904 * The states of this process and its threads may have changed
905 * by now. Assuming that there is only one pageout daemon thread,
906 * this process should still be in memory.
908 KASSERT((p->p_flag & (P_INMEM | P_SWAPPINGOUT | P_SWAPPINGIN)) ==
909 P_INMEM, ("swapout: lost a swapout race?"));
912 * Remember the resident count.
914 p->p_vmspace->vm_swrss = vmspace_resident_count(p->p_vmspace);
917 * Check and mark all threads before we proceed.
919 p->p_flag &= ~P_INMEM;
920 p->p_flag |= P_SWAPPINGOUT;
921 FOREACH_THREAD_IN_PROC(p, td) {
923 if (!thread_safetoswapout(td)) {
928 td->td_flags &= ~TDF_INMEM;
932 td = FIRST_THREAD_IN_PROC(p);
933 ++td->td_ru.ru_nswap;
937 * This list is stable because all threads are now prevented from
938 * running. The list is only modified in the context of a running
939 * thread in this process.
941 FOREACH_THREAD_IN_PROC(p, td)
942 vm_thread_swapout(td);
945 p->p_flag &= ~P_SWAPPINGOUT;