/*-
* SPDX-License-Identifier: (BSD-4-Clause AND MIT-CMU)
*
* Copyright (c) 1991 Regents of the University of California.
* All rights reserved.
* Copyright (c) 1994 John S. Dyson
* All rights reserved.
* Copyright (c) 1994 David Greenman
* All rights reserved.
* Copyright (c) 2005 Yahoo! Technologies Norway AS
* All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* The Mach Operating System project at Carnegie-Mellon University.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* from: @(#)vm_pageout.c 7.4 (Berkeley) 5/7/91
*
*
* Copyright (c) 1987, 1990 Carnegie-Mellon University.
* All rights reserved.
*
* Authors: Avadis Tevanian, Jr., Michael Wayne Young
*
* Permission to use, copy, modify and distribute this software and
* its documentation is hereby granted, provided that both the copyright
* notice and this permission notice appear in all copies of the
* software, derivative works or modified versions, and any portions
* thereof, and that both notices appear in supporting documentation.
*
* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
* FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
*
* Carnegie Mellon requests users of this software to return to
*
* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
* School of Computer Science
* Carnegie Mellon University
* Pittsburgh PA 15213-3890
*
* any improvements or extensions that they make and grant Carnegie the
* rights to redistribute these changes.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_kstack_pages.h"
#include "opt_kstack_max_pages.h"
#include "opt_vm.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/limits.h>
#include <sys/kernel.h>
#include <sys/eventhandler.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/_kstack_cache.h>
#include <sys/kthread.h>
#include <sys/ktr.h>
#include <sys/mount.h>
#include <sys/racct.h>
#include <sys/resourcevar.h>
#include <sys/sched.h>
#include <sys/sdt.h>
#include <sys/signalvar.h>
#include <sys/smp.h>
#include <sys/time.h>
#include <sys/vnode.h>
#include <sys/vmmeter.h>
#include <sys/rwlock.h>
#include <sys/sx.h>
#include <sys/sysctl.h>
#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/vm_object.h>
#include <vm/vm_page.h>
#include <vm/vm_map.h>
#include <vm/vm_pageout.h>
#include <vm/vm_pager.h>
#include <vm/vm_phys.h>
#include <vm/swap_pager.h>
#include <vm/vm_extern.h>
#include <vm/uma.h>
/* the kernel process "vm_daemon" */
static void vm_daemon(void);
static struct proc *vmproc;
static struct kproc_desc vm_kp = {
"vmdaemon",
vm_daemon,
&vmproc
};
SYSINIT(vmdaemon, SI_SUB_KTHREAD_VM, SI_ORDER_FIRST, kproc_start, &vm_kp);
static int vm_swap_enabled = 1;
static int vm_swap_idle_enabled = 0;
SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled, CTLFLAG_RW,
&vm_swap_enabled, 0,
"Enable entire process swapout");
SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled, CTLFLAG_RW,
&vm_swap_idle_enabled, 0,
"Allow swapout on idle criteria");
/*
* Swap_idle_threshold1 is the guaranteed swapped in time for a process
*/
static int swap_idle_threshold1 = 2;
SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold1, CTLFLAG_RW,
&swap_idle_threshold1, 0,
"Guaranteed swapped in time for a process");
/*
* Swap_idle_threshold2 is the time that a process can be idle before
* it will be swapped out, if idle swapping is enabled.
*/
static int swap_idle_threshold2 = 10;
SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold2, CTLFLAG_RW,
&swap_idle_threshold2, 0,
"Time before a process will be swapped out");
static int vm_pageout_req_swapout; /* XXX */
static int vm_daemon_needed;
static struct mtx vm_daemon_mtx;
/* Allow for use by vm_pageout before vm_daemon is initialized. */
MTX_SYSINIT(vm_daemon, &vm_daemon_mtx, "vm daemon", MTX_DEF);
static int swapped_cnt;
static int swap_inprogress; /* Pending swap-ins done outside swapper. */
static int last_swapin;
static void swapclear(struct proc *);
static int swapout(struct proc *);
static void vm_swapout_map_deactivate_pages(vm_map_t, long);
static void vm_swapout_object_deactivate_pages(pmap_t, vm_object_t, long);
static void swapout_procs(int action);
static void vm_req_vmdaemon(int req);
static void vm_thread_swapout(struct thread *td);
/*
* vm_swapout_object_deactivate_pages
*
* Deactivate enough pages to satisfy the inactive target
* requirements.
*
* The object and map must be locked.
*/
static void
vm_swapout_object_deactivate_pages(pmap_t pmap, vm_object_t first_object,
long desired)
{
vm_object_t backing_object, object;
vm_page_t p;
int act_delta, remove_mode;
VM_OBJECT_ASSERT_LOCKED(first_object);
if ((first_object->flags & OBJ_FICTITIOUS) != 0)
return;
for (object = first_object;; object = backing_object) {
if (pmap_resident_count(pmap) <= desired)
goto unlock_return;
VM_OBJECT_ASSERT_LOCKED(object);
if ((object->flags & OBJ_UNMANAGED) != 0 ||
object->paging_in_progress != 0)
goto unlock_return;
remove_mode = 0;
if (object->shadow_count > 1)
remove_mode = 1;
/*
* Scan the object's entire memory queue.
*/
TAILQ_FOREACH(p, &object->memq, listq) {
if (pmap_resident_count(pmap) <= desired)
goto unlock_return;
if (should_yield())
goto unlock_return;
if (vm_page_busied(p))
continue;
VM_CNT_INC(v_pdpages);
vm_page_lock(p);
if (vm_page_held(p) ||
!pmap_page_exists_quick(pmap, p)) {
vm_page_unlock(p);
continue;
}
act_delta = pmap_ts_referenced(p);
if ((p->aflags & PGA_REFERENCED) != 0) {
if (act_delta == 0)
act_delta = 1;
vm_page_aflag_clear(p, PGA_REFERENCED);
}
if (!vm_page_active(p) && act_delta != 0) {
vm_page_activate(p);
p->act_count += act_delta;
} else if (vm_page_active(p)) {
if (act_delta == 0) {
p->act_count -= min(p->act_count,
ACT_DECLINE);
if (!remove_mode && p->act_count == 0) {
pmap_remove_all(p);
vm_page_deactivate(p);
} else
vm_page_requeue(p);
} else {
vm_page_activate(p);
if (p->act_count < ACT_MAX -
ACT_ADVANCE)
p->act_count += ACT_ADVANCE;
vm_page_requeue(p);
}
} else if (vm_page_inactive(p))
pmap_remove_all(p);
vm_page_unlock(p);
}
if ((backing_object = object->backing_object) == NULL)
goto unlock_return;
VM_OBJECT_RLOCK(backing_object);
if (object != first_object)
VM_OBJECT_RUNLOCK(object);
}
unlock_return:
if (object != first_object)
VM_OBJECT_RUNLOCK(object);
}
/*
* deactivate some number of pages in a map, try to do it fairly, but
* that is really hard to do.
*/
static void
vm_swapout_map_deactivate_pages(vm_map_t map, long desired)
{
vm_map_entry_t tmpe;
vm_object_t obj, bigobj;
int nothingwired;
if (!vm_map_trylock_read(map))
return;
bigobj = NULL;
nothingwired = TRUE;
/*
* first, search out the biggest object, and try to free pages from
* that.
*/
tmpe = map->header.next;
while (tmpe != &map->header) {
if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) {
obj = tmpe->object.vm_object;
if (obj != NULL && VM_OBJECT_TRYRLOCK(obj)) {
if (obj->shadow_count <= 1 &&
(bigobj == NULL ||
bigobj->resident_page_count <
obj->resident_page_count)) {
if (bigobj != NULL)
VM_OBJECT_RUNLOCK(bigobj);
bigobj = obj;
} else
VM_OBJECT_RUNLOCK(obj);
}
}
if (tmpe->wired_count > 0)
nothingwired = FALSE;
tmpe = tmpe->next;
}
if (bigobj != NULL) {
vm_swapout_object_deactivate_pages(map->pmap, bigobj, desired);
VM_OBJECT_RUNLOCK(bigobj);
}
/*
* Next, hunt around for other pages to deactivate. We actually
* do this search sort of wrong -- .text first is not the best idea.
*/
tmpe = map->header.next;
while (tmpe != &map->header) {
if (pmap_resident_count(vm_map_pmap(map)) <= desired)
break;
if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) {
obj = tmpe->object.vm_object;
if (obj != NULL) {
VM_OBJECT_RLOCK(obj);
vm_swapout_object_deactivate_pages(map->pmap,
obj, desired);
VM_OBJECT_RUNLOCK(obj);
}
}
tmpe = tmpe->next;
}
/*
* Remove all mappings if a process is swapped out, this will free page
* table pages.
*/
if (desired == 0 && nothingwired) {
pmap_remove(vm_map_pmap(map), vm_map_min(map),
vm_map_max(map));
}
vm_map_unlock_read(map);
}
/*
* Swap out requests
*/
#define VM_SWAP_NORMAL 1
#define VM_SWAP_IDLE 2
void
vm_swapout_run(void)
{
if (vm_swap_enabled)
vm_req_vmdaemon(VM_SWAP_NORMAL);
}
/*
* Idle process swapout -- run once per second when pagedaemons are
* reclaiming pages.
*/
void
vm_swapout_run_idle(void)
{
static long lsec;
if (!vm_swap_idle_enabled || time_second == lsec)
return;
vm_req_vmdaemon(VM_SWAP_IDLE);
lsec = time_second;
}
static void
vm_req_vmdaemon(int req)
{
static int lastrun = 0;
mtx_lock(&vm_daemon_mtx);
vm_pageout_req_swapout |= req;
if ((ticks > (lastrun + hz)) || (ticks < lastrun)) {
wakeup(&vm_daemon_needed);
lastrun = ticks;
}
mtx_unlock(&vm_daemon_mtx);
}
static void
vm_daemon(void)
{
struct rlimit rsslim;
struct proc *p;
struct thread *td;
struct vmspace *vm;
int breakout, swapout_flags, tryagain, attempts;
#ifdef RACCT
uint64_t rsize, ravailable;
#endif
while (TRUE) {
mtx_lock(&vm_daemon_mtx);
msleep(&vm_daemon_needed, &vm_daemon_mtx, PPAUSE, "psleep",
#ifdef RACCT
racct_enable ? hz : 0
#else
0
#endif
);
swapout_flags = vm_pageout_req_swapout;
vm_pageout_req_swapout = 0;
mtx_unlock(&vm_daemon_mtx);
if (swapout_flags != 0) {
/*
* Drain the per-CPU page queue batches as a deadlock
* avoidance measure.
*/
if ((swapout_flags & VM_SWAP_NORMAL) != 0)
vm_page_drain_pqbatch();
swapout_procs(swapout_flags);
}
/*
* scan the processes for exceeding their rlimits or if
* process is swapped out -- deactivate pages
*/
tryagain = 0;
attempts = 0;
again:
attempts++;
sx_slock(&allproc_lock);
FOREACH_PROC_IN_SYSTEM(p) {
vm_pindex_t limit, size;
/*
* if this is a system process or if we have already
* looked at this process, skip it.
*/
PROC_LOCK(p);
if (p->p_state != PRS_NORMAL ||
p->p_flag & (P_INEXEC | P_SYSTEM | P_WEXIT)) {
PROC_UNLOCK(p);
continue;
}
/*
* if the process is in a non-running type state,
* don't touch it.
*/
breakout = 0;
FOREACH_THREAD_IN_PROC(p, td) {
thread_lock(td);
if (!TD_ON_RUNQ(td) &&
!TD_IS_RUNNING(td) &&
!TD_IS_SLEEPING(td) &&
!TD_IS_SUSPENDED(td)) {
thread_unlock(td);
breakout = 1;
break;
}
thread_unlock(td);
}
if (breakout) {
PROC_UNLOCK(p);
continue;
}
/*
* get a limit
*/
lim_rlimit_proc(p, RLIMIT_RSS, &rsslim);
limit = OFF_TO_IDX(
qmin(rsslim.rlim_cur, rsslim.rlim_max));
/*
* let processes that are swapped out really be
* swapped out set the limit to nothing (will force a
* swap-out.)
*/
if ((p->p_flag & P_INMEM) == 0)
limit = 0; /* XXX */
vm = vmspace_acquire_ref(p);
_PHOLD_LITE(p);
PROC_UNLOCK(p);
if (vm == NULL) {
PRELE(p);
continue;
}
sx_sunlock(&allproc_lock);
size = vmspace_resident_count(vm);
if (size >= limit) {
vm_swapout_map_deactivate_pages(
&vm->vm_map, limit);
size = vmspace_resident_count(vm);
}
#ifdef RACCT
if (racct_enable) {
rsize = IDX_TO_OFF(size);
PROC_LOCK(p);
if (p->p_state == PRS_NORMAL)
racct_set(p, RACCT_RSS, rsize);
ravailable = racct_get_available(p, RACCT_RSS);
PROC_UNLOCK(p);
if (rsize > ravailable) {
/*
* Don't be overly aggressive; this
* might be an innocent process,
* and the limit could've been exceeded
* by some memory hog. Don't try
* to deactivate more than 1/4th
* of process' resident set size.
*/
if (attempts <= 8) {
if (ravailable < rsize -
(rsize / 4)) {
ravailable = rsize -
(rsize / 4);
}
}
vm_swapout_map_deactivate_pages(
&vm->vm_map,
OFF_TO_IDX(ravailable));
/* Update RSS usage after paging out. */
size = vmspace_resident_count(vm);
rsize = IDX_TO_OFF(size);
PROC_LOCK(p);
if (p->p_state == PRS_NORMAL)
racct_set(p, RACCT_RSS, rsize);
PROC_UNLOCK(p);
if (rsize > ravailable)
tryagain = 1;
}
}
#endif
vmspace_free(vm);
sx_slock(&allproc_lock);
PRELE(p);
}
sx_sunlock(&allproc_lock);
if (tryagain != 0 && attempts <= 10) {
maybe_yield();
goto again;
}
}
}
/*
* Allow a thread's kernel stack to be paged out.
*/
static void
vm_thread_swapout(struct thread *td)
{
vm_object_t ksobj;
vm_page_t m;
int i, pages;
cpu_thread_swapout(td);
pages = td->td_kstack_pages;
ksobj = td->td_kstack_obj;
pmap_qremove(td->td_kstack, pages);
VM_OBJECT_WLOCK(ksobj);
for (i = 0; i < pages; i++) {
m = vm_page_lookup(ksobj, i);
if (m == NULL)
panic("vm_thread_swapout: kstack already missing?");
vm_page_dirty(m);
vm_page_lock(m);
vm_page_unwire(m, PQ_LAUNDRY);
vm_page_unlock(m);
}
VM_OBJECT_WUNLOCK(ksobj);
}
/*
* Bring the kernel stack for a specified thread back in.
*/
static void
vm_thread_swapin(struct thread *td, int oom_alloc)
{
vm_object_t ksobj;
vm_page_t ma[KSTACK_MAX_PAGES];
int a, count, i, j, pages, rv;
pages = td->td_kstack_pages;
ksobj = td->td_kstack_obj;
VM_OBJECT_WLOCK(ksobj);
(void)vm_page_grab_pages(ksobj, 0, oom_alloc | VM_ALLOC_WIRED, ma,
pages);
for (i = 0; i < pages;) {
vm_page_assert_xbusied(ma[i]);
if (ma[i]->valid == VM_PAGE_BITS_ALL) {
vm_page_xunbusy(ma[i]);
i++;
continue;
}
vm_object_pip_add(ksobj, 1);
for (j = i + 1; j < pages; j++)
if (ma[j]->valid == VM_PAGE_BITS_ALL)
break;
rv = vm_pager_has_page(ksobj, ma[i]->pindex, NULL, &a);
KASSERT(rv == 1, ("%s: missing page %p", __func__, ma[i]));
count = min(a + 1, j - i);
rv = vm_pager_get_pages(ksobj, ma + i, count, NULL, NULL);
KASSERT(rv == VM_PAGER_OK, ("%s: cannot get kstack for proc %d",
__func__, td->td_proc->p_pid));
vm_object_pip_wakeup(ksobj);
for (j = i; j < i + count; j++)
vm_page_xunbusy(ma[j]);
i += count;
}
VM_OBJECT_WUNLOCK(ksobj);
pmap_qenter(td->td_kstack, ma, pages);
cpu_thread_swapin(td);
}
void
faultin(struct proc *p)
{
struct thread *td;
int oom_alloc;
PROC_LOCK_ASSERT(p, MA_OWNED);
/*
* If another process is swapping in this process,
* just wait until it finishes.
*/
if (p->p_flag & P_SWAPPINGIN) {
while (p->p_flag & P_SWAPPINGIN)
msleep(&p->p_flag, &p->p_mtx, PVM, "faultin", 0);
return;
}
if ((p->p_flag & P_INMEM) == 0) {
oom_alloc = (p->p_flag & P_WKILLED) != 0 ? VM_ALLOC_SYSTEM :
VM_ALLOC_NORMAL;
/*
* Don't let another thread swap process p out while we are
* busy swapping it in.
*/
++p->p_lock;
p->p_flag |= P_SWAPPINGIN;
PROC_UNLOCK(p);
sx_xlock(&allproc_lock);
MPASS(swapped_cnt > 0);
swapped_cnt--;
if (curthread != &thread0)
swap_inprogress++;
sx_xunlock(&allproc_lock);
/*
* We hold no lock here because the list of threads
* can not change while all threads in the process are
* swapped out.
*/
FOREACH_THREAD_IN_PROC(p, td)
vm_thread_swapin(td, oom_alloc);
if (curthread != &thread0) {
sx_xlock(&allproc_lock);
MPASS(swap_inprogress > 0);
swap_inprogress--;
last_swapin = ticks;
sx_xunlock(&allproc_lock);
}
PROC_LOCK(p);
swapclear(p);
p->p_swtick = ticks;
/* Allow other threads to swap p out now. */
wakeup(&p->p_flag);
--p->p_lock;
}
}
/*
* This swapin algorithm attempts to swap-in processes only if there
* is enough space for them. Of course, if a process waits for a long
* time, it will be swapped in anyway.
*/
static struct proc *
swapper_selector(bool wkilled_only)
{
struct proc *p, *res;
struct thread *td;
int ppri, pri, slptime, swtime;
sx_assert(&allproc_lock, SA_SLOCKED);
if (swapped_cnt == 0)
return (NULL);
res = NULL;
ppri = INT_MIN;
FOREACH_PROC_IN_SYSTEM(p) {
PROC_LOCK(p);
if (p->p_state == PRS_NEW || (p->p_flag & (P_SWAPPINGOUT |
P_SWAPPINGIN | P_INMEM)) != 0) {
PROC_UNLOCK(p);
continue;
}
if (p->p_state == PRS_NORMAL && (p->p_flag & P_WKILLED) != 0) {
/*
* A swapped-out process might have mapped a
* large portion of the system's pages as
* anonymous memory. There is no other way to
* release the memory other than to kill the
* process, for which we need to swap it in.
*/
return (p);
}
if (wkilled_only) {
PROC_UNLOCK(p);
continue;
}
swtime = (ticks - p->p_swtick) / hz;
FOREACH_THREAD_IN_PROC(p, td) {
/*
* An otherwise runnable thread of a process
* swapped out has only the TDI_SWAPPED bit set.
*/
thread_lock(td);
if (td->td_inhibitors == TDI_SWAPPED) {
slptime = (ticks - td->td_slptick) / hz;
pri = swtime + slptime;
if ((td->td_flags & TDF_SWAPINREQ) == 0)
pri -= p->p_nice * 8;
/*
* if this thread is higher priority
* and there is enough space, then select
* this process instead of the previous
* selection.
*/
if (pri > ppri) {
res = p;
ppri = pri;
}
}
thread_unlock(td);
}
PROC_UNLOCK(p);
}
if (res != NULL)
PROC_LOCK(res);
return (res);
}
#define SWAPIN_INTERVAL (MAXSLP * hz / 2)
/*
* Limit swapper to swap in one non-WKILLED process in MAXSLP/2
* interval, assuming that there is:
* - at least one domain that is not suffering from a shortage of free memory;
* - no parallel swap-ins;
* - no other swap-ins in the current SWAPIN_INTERVAL.
*/
static bool
swapper_wkilled_only(void)
{
return (vm_page_count_min_set(&all_domains) || swap_inprogress > 0 ||
(u_int)(ticks - last_swapin) < SWAPIN_INTERVAL);
}
void
swapper(void)
{
struct proc *p;
for (;;) {
sx_slock(&allproc_lock);
p = swapper_selector(swapper_wkilled_only());
sx_sunlock(&allproc_lock);
if (p == NULL) {
tsleep(&proc0, PVM, "swapin", SWAPIN_INTERVAL);
} else {
PROC_LOCK_ASSERT(p, MA_OWNED);
/*
* Another process may be bringing or may have
* already brought this process in while we
* traverse all threads. Or, this process may
* have exited or even being swapped out
* again.
*/
if (p->p_state == PRS_NORMAL && (p->p_flag & (P_INMEM |
P_SWAPPINGOUT | P_SWAPPINGIN)) == 0) {
faultin(p);
}
PROC_UNLOCK(p);
}
}
}
/*
* First, if any processes have been sleeping or stopped for at least
* "swap_idle_threshold1" seconds, they are swapped out. If, however,
* no such processes exist, then the longest-sleeping or stopped
* process is swapped out. Finally, and only as a last resort, if
* there are no sleeping or stopped processes, the longest-resident
* process is swapped out.
*/
static void
swapout_procs(int action)
{
struct proc *p;
struct thread *td;
int slptime;
bool didswap, doswap;
MPASS((action & (VM_SWAP_NORMAL | VM_SWAP_IDLE)) != 0);
didswap = false;
sx_slock(&allproc_lock);
FOREACH_PROC_IN_SYSTEM(p) {
/*
* Filter out not yet fully constructed processes. Do
* not swap out held processes. Avoid processes which
* are system, exiting, execing, traced, already swapped
* out or are in the process of being swapped in or out.
*/
PROC_LOCK(p);
if (p->p_state != PRS_NORMAL || p->p_lock != 0 || (p->p_flag &
(P_SYSTEM | P_WEXIT | P_INEXEC | P_STOPPED_SINGLE |
P_TRACED | P_SWAPPINGOUT | P_SWAPPINGIN | P_INMEM)) !=
P_INMEM) {
PROC_UNLOCK(p);
continue;
}
/*
* Further consideration of this process for swap out
* requires iterating over its threads. We release
* allproc_lock here so that process creation and
* destruction are not blocked while we iterate.
*
* To later reacquire allproc_lock and resume
* iteration over the allproc list, we will first have
* to release the lock on the process. We place a
* hold on the process so that it remains in the
* allproc list while it is unlocked.
*/
_PHOLD_LITE(p);
sx_sunlock(&allproc_lock);
/*
* Do not swapout a realtime process.
* Guarantee swap_idle_threshold1 time in memory.
* If the system is under memory stress, or if we are
* swapping idle processes >= swap_idle_threshold2,
* then swap the process out.
*/
doswap = true;
FOREACH_THREAD_IN_PROC(p, td) {
thread_lock(td);
slptime = (ticks - td->td_slptick) / hz;
if (PRI_IS_REALTIME(td->td_pri_class) ||
slptime < swap_idle_threshold1 ||
!thread_safetoswapout(td) ||
((action & VM_SWAP_NORMAL) == 0 &&
slptime < swap_idle_threshold2))
doswap = false;
thread_unlock(td);
if (!doswap)
break;
}
if (doswap && swapout(p) == 0)
didswap = true;
PROC_UNLOCK(p);
if (didswap) {
sx_xlock(&allproc_lock);
swapped_cnt++;
sx_downgrade(&allproc_lock);
} else
sx_slock(&allproc_lock);
PRELE(p);
}
sx_sunlock(&allproc_lock);
/*
* If we swapped something out, and another process needed memory,
* then wakeup the sched process.
*/
if (didswap)
wakeup(&proc0);
}
static void
swapclear(struct proc *p)
{
struct thread *td;
PROC_LOCK_ASSERT(p, MA_OWNED);
FOREACH_THREAD_IN_PROC(p, td) {
thread_lock(td);
td->td_flags |= TDF_INMEM;
td->td_flags &= ~TDF_SWAPINREQ;
TD_CLR_SWAPPED(td);
if (TD_CAN_RUN(td))
if (setrunnable(td)) {
#ifdef INVARIANTS
/*
* XXX: We just cleared TDI_SWAPPED
* above and set TDF_INMEM, so this
* should never happen.
*/
panic("not waking up swapper");
#endif
}
thread_unlock(td);
}
p->p_flag &= ~(P_SWAPPINGIN | P_SWAPPINGOUT);
p->p_flag |= P_INMEM;
}
static int
swapout(struct proc *p)
{
struct thread *td;
PROC_LOCK_ASSERT(p, MA_OWNED);
/*
* The states of this process and its threads may have changed
* by now. Assuming that there is only one pageout daemon thread,
* this process should still be in memory.
*/
KASSERT((p->p_flag & (P_INMEM | P_SWAPPINGOUT | P_SWAPPINGIN)) ==
P_INMEM, ("swapout: lost a swapout race?"));
/*
* Remember the resident count.
*/
p->p_vmspace->vm_swrss = vmspace_resident_count(p->p_vmspace);
/*
* Check and mark all threads before we proceed.
*/
p->p_flag &= ~P_INMEM;
p->p_flag |= P_SWAPPINGOUT;
FOREACH_THREAD_IN_PROC(p, td) {
thread_lock(td);
if (!thread_safetoswapout(td)) {
thread_unlock(td);
swapclear(p);
return (EBUSY);
}
td->td_flags &= ~TDF_INMEM;
TD_SET_SWAPPED(td);
thread_unlock(td);
}
td = FIRST_THREAD_IN_PROC(p);
++td->td_ru.ru_nswap;
PROC_UNLOCK(p);
/*
* This list is stable because all threads are now prevented from
* running. The list is only modified in the context of a running
* thread in this process.
*/
FOREACH_THREAD_IN_PROC(p, td)
vm_thread_swapout(td);
PROC_LOCK(p);
p->p_flag &= ~P_SWAPPINGOUT;
p->p_swtick = ticks;
return (0);
}
