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freebsd/sys/vm/vm_pageout.c
David Greenman eadf9e27cd These changes fix a couple of lingering VM problems: 
1.	The pageout daemon used to block under certain
	circumstances, and we needed to add new functionality
	that would cause the pageout daemon to block more often.
	Now, the pageout daemon mostly just gets rid of pages
	and kills processes when the system is out of swap.
	The swapping, rss limiting and object cache trimming
	have been folded into a new daemon called "vmdaemon".
	This new daemon does things that need to be done for
	the VM system, but can block.  For example, if the
	vmdaemon blocks for memory, the pageout daemon
	can take care of it.  If the pageout daemon had
	blocked for memory, it was difficult to handle
	the situation correctly (and in some cases, was
	impossible).

2.	The collapse problem has now been entirely fixed.
	It now appears to be impossible to accumulate unnecessary
	vm objects.  The object collapsing now occurs when ref counts
	drop to one (where it is more likely to be more simple anyway
	because less pages would be out on disk.)  The original
	fixes were incomplete in that pathological circumstances
	could still be contrived to cause uncontrolled growth
	of swap.  Also, the old code still, under steady state
	conditions, used more swap space than necessary.  When
	using the new code, users will generally notice a
	significant decrease in swap space usage, and theoretically,
	the system should be leaving fewer unused pages around
	competing for memory.

Submitted by:	John Dyson
1994-11-25 07:58:29 +00:00

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/*
* 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.
*
* 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.
*
* $Id: vm_pageout.c,v 1.26 1994/11/17 06:24:25 davidg Exp $
*/
/*
* The proverbial page-out daemon.
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/resourcevar.h>
#include <sys/malloc.h>
#include <vm/vm.h>
#include <vm/vm_page.h>
#include <vm/vm_pageout.h>
#include <vm/swap_pager.h>
extern vm_map_t kmem_map;
int vm_pages_needed; /* Event on which pageout daemon sleeps */
int vm_pagescanner; /* Event on which pagescanner sleeps */
int vm_pageout_free_min = 0; /* Stop pageout to wait for pagers at this free level */
int vm_pageout_pages_needed = 0; /* flag saying that the pageout daemon needs pages */
int vm_page_pagesfreed;
int vm_desired_cache_size;
extern int npendingio;
extern int hz;
int vm_pageout_proc_limit;
int vm_pageout_req_swapout;
int vm_daemon_needed;
extern int nswiodone;
extern int swap_pager_full;
extern int vm_swap_size;
extern int swap_pager_ready();
#define MAXREF 32767
#define MAXSCAN 512 /* maximum number of pages to scan in active queue */
/* set the "clock" hands to be (MAXSCAN * 4096) Bytes */
#define ACT_DECLINE 1
#define ACT_ADVANCE 3
#define ACT_MAX 100
#define LOWATER ((2048*1024)/NBPG)
#define VM_PAGEOUT_PAGE_COUNT 8
int vm_pageout_page_count = VM_PAGEOUT_PAGE_COUNT;
int vm_pageout_req_do_stats;
int vm_page_max_wired = 0; /* XXX max # of wired pages system-wide */
/*
* vm_pageout_clean:
* cleans a vm_page
*/
int
vm_pageout_clean(m, sync)
register vm_page_t m;
int sync;
{
/*
* Clean the page and remove it from the
* laundry.
*
* We set the busy bit to cause
* potential page faults on this page to
* block.
*
* And we set pageout-in-progress to keep
* the object from disappearing during
* pageout. This guarantees that the
* page won't move from the inactive
* queue. (However, any other page on
* the inactive queue may move!)
*/
register vm_object_t object;
register vm_pager_t pager;
int pageout_status[VM_PAGEOUT_PAGE_COUNT];
vm_page_t ms[VM_PAGEOUT_PAGE_COUNT];
int pageout_count;
int anyok=0;
int i;
vm_offset_t offset = m->offset;
object = m->object;
if (!object) {
printf("pager: object missing\n");
return 0;
}
/*
* Try to collapse the object before
* making a pager for it. We must
* unlock the page queues first.
* We try to defer the creation of a pager
* until all shadows are not paging. This
* allows vm_object_collapse to work better and
* helps control swap space size.
* (J. Dyson 11 Nov 93)
*/
if (!object->pager &&
cnt.v_free_count < vm_pageout_free_min)
return 0;
if( !sync) {
if (object->shadow) {
vm_object_collapse(object);
}
if ((m->busy != 0) ||
(m->flags & PG_BUSY) || (m->hold_count != 0)) {
return 0;
}
}
pageout_count = 1;
ms[0] = m;
pager = object->pager;
if (pager) {
for (i = 1; i < vm_pageout_page_count; i++) {
ms[i] = vm_page_lookup(object, offset+i*NBPG);
if (ms[i]) {
if (((ms[i]->flags & PG_CLEAN) != 0) &&
pmap_is_modified(VM_PAGE_TO_PHYS(ms[i]))) {
ms[i]->flags &= ~PG_CLEAN;
}
if (( ((ms[i]->flags & (PG_CLEAN|PG_INACTIVE|PG_BUSY)) == PG_INACTIVE)
|| ( (ms[i]->flags & (PG_CLEAN|PG_BUSY)) == 0 && sync == VM_PAGEOUT_FORCE))
&& (ms[i]->wire_count == 0)
&& (ms[i]->busy == 0)
&& (ms[i]->hold_count == 0))
pageout_count++;
else
break;
} else
break;
}
for(i=0;i<pageout_count;i++) {
ms[i]->flags |= PG_BUSY;
pmap_page_protect(VM_PAGE_TO_PHYS(ms[i]), VM_PROT_READ);
}
object->paging_in_progress += pageout_count;
} else {
m->flags |= PG_BUSY;
pmap_page_protect(VM_PAGE_TO_PHYS(m), VM_PROT_READ);
object->paging_in_progress++;
pager = vm_pager_allocate(PG_DFLT, (caddr_t)0,
object->size, VM_PROT_ALL, 0);
if (pager != NULL) {
vm_object_setpager(object, pager, 0, FALSE);
}
}
/*
* If there is no pager for the page,
* use the default pager. If there's
* no place to put the page at the
* moment, leave it in the laundry and
* hope that there will be paging space
* later.
*/
if ((pager && pager->pg_type == PG_SWAP) ||
cnt.v_free_count >= vm_pageout_free_min) {
if( pageout_count == 1) {
pageout_status[0] = pager ?
vm_pager_put(pager, m,
((sync || (object == kernel_object)) ? TRUE: FALSE)) :
VM_PAGER_FAIL;
} else {
if( !pager) {
for(i=0;i<pageout_count;i++)
pageout_status[i] = VM_PAGER_FAIL;
} else {
vm_pager_put_pages(pager, ms, pageout_count,
((sync || (object == kernel_object)) ? TRUE : FALSE),
pageout_status);
}
}
} else {
for(i=0;i<pageout_count;i++)
pageout_status[i] = VM_PAGER_FAIL;
}
for(i=0;i<pageout_count;i++) {
switch (pageout_status[i]) {
case VM_PAGER_OK:
ms[i]->flags &= ~PG_LAUNDRY;
++anyok;
break;
case VM_PAGER_PEND:
ms[i]->flags &= ~PG_LAUNDRY;
++anyok;
break;
case VM_PAGER_BAD:
/*
* Page outside of range of object.
* Right now we essentially lose the
* changes by pretending it worked.
*/
ms[i]->flags &= ~PG_LAUNDRY;
ms[i]->flags |= PG_CLEAN;
pmap_clear_modify(VM_PAGE_TO_PHYS(ms[i]));
break;
case VM_PAGER_ERROR:
case VM_PAGER_FAIL:
/*
* If page couldn't be paged out, then
* reactivate the page so it doesn't
* clog the inactive list. (We will
* try paging out it again later).
*/
if (ms[i]->flags & PG_INACTIVE)
vm_page_activate(ms[i]);
break;
case VM_PAGER_AGAIN:
break;
}
/*
* If the operation is still going, leave
* the page busy to block all other accesses.
* Also, leave the paging in progress
* indicator set so that we don't attempt an
* object collapse.
*/
if (pageout_status[i] != VM_PAGER_PEND) {
PAGE_WAKEUP(ms[i]);
if (--object->paging_in_progress == 0)
wakeup((caddr_t) object);
if ((ms[i]->flags & PG_REFERENCED) ||
pmap_is_referenced(VM_PAGE_TO_PHYS(ms[i]))) {
pmap_clear_reference(VM_PAGE_TO_PHYS(ms[i]));
ms[i]->flags &= ~PG_REFERENCED;
if( ms[i]->flags & PG_INACTIVE)
vm_page_activate(ms[i]);
}
}
}
return anyok;
}
/*
* vm_pageout_object_deactivate_pages
*
* deactivate enough pages to satisfy the inactive target
* requirements or if vm_page_proc_limit is set, then
* deactivate all of the pages in the object and its
* shadows.
*
* The object and map must be locked.
*/
int
vm_pageout_object_deactivate_pages(map, object, count)
vm_map_t map;
vm_object_t object;
int count;
{
register vm_page_t p, next;
int rcount;
int dcount;
dcount = 0;
if (count == 0)
count = 1;
if (object->shadow) {
if( object->shadow->ref_count == 1)
dcount += vm_pageout_object_deactivate_pages(map, object->shadow, count/2);
}
if (object->paging_in_progress)
return dcount;
/*
* scan the objects entire memory queue
*/
rcount = object->resident_page_count;
p = object->memq.tqh_first;
while (p && (rcount-- > 0)) {
next = p->listq.tqe_next;
cnt.v_pdpages++;
vm_page_lock_queues();
/*
* if a page is active, not wired and is in the processes pmap,
* then deactivate the page.
*/
if ((p->flags & (PG_ACTIVE|PG_BUSY)) == PG_ACTIVE &&
p->wire_count == 0 &&
p->hold_count == 0 &&
p->busy == 0 &&
pmap_page_exists(vm_map_pmap(map), VM_PAGE_TO_PHYS(p))) {
if (!pmap_is_referenced(VM_PAGE_TO_PHYS(p)) &&
(p->flags & PG_REFERENCED) == 0) {
p->act_count -= min(p->act_count, ACT_DECLINE);
/*
* if the page act_count is zero -- then we deactivate
*/
if (!p->act_count) {
vm_page_deactivate(p);
pmap_page_protect(VM_PAGE_TO_PHYS(p),
VM_PROT_NONE);
/*
* else if on the next go-around we will deactivate the page
* we need to place the page on the end of the queue to age
* the other pages in memory.
*/
} else {
TAILQ_REMOVE(&vm_page_queue_active, p, pageq);
TAILQ_INSERT_TAIL(&vm_page_queue_active, p, pageq);
TAILQ_REMOVE(&object->memq, p, listq);
TAILQ_INSERT_TAIL(&object->memq, p, listq);
}
/*
* see if we are done yet
*/
if (p->flags & PG_INACTIVE) {
--count;
++dcount;
if (count <= 0 &&
cnt.v_inactive_count > cnt.v_inactive_target) {
vm_page_unlock_queues();
return dcount;
}
}
} else {
/*
* Move the page to the bottom of the queue.
*/
pmap_clear_reference(VM_PAGE_TO_PHYS(p));
p->flags &= ~PG_REFERENCED;
if (p->act_count < ACT_MAX)
p->act_count += ACT_ADVANCE;
TAILQ_REMOVE(&vm_page_queue_active, p, pageq);
TAILQ_INSERT_TAIL(&vm_page_queue_active, p, pageq);
TAILQ_REMOVE(&object->memq, p, listq);
TAILQ_INSERT_TAIL(&object->memq, p, listq);
}
}
vm_page_unlock_queues();
p = next;
}
return dcount;
}
/*
* deactivate some number of pages in a map, try to do it fairly, but
* that is really hard to do.
*/
void
vm_pageout_map_deactivate_pages(map, entry, count, freeer)
vm_map_t map;
vm_map_entry_t entry;
int *count;
int (*freeer)(vm_map_t, vm_object_t, int);
{
vm_map_t tmpm;
vm_map_entry_t tmpe;
vm_object_t obj;
if (*count <= 0)
return;
vm_map_reference(map);
if (!lock_try_read(&map->lock)) {
vm_map_deallocate(map);
return;
}
if (entry == 0) {
tmpe = map->header.next;
while (tmpe != &map->header && *count > 0) {
vm_pageout_map_deactivate_pages(map, tmpe, count, freeer);
tmpe = tmpe->next;
};
} else if (entry->is_sub_map || entry->is_a_map) {
tmpm = entry->object.share_map;
tmpe = tmpm->header.next;
while (tmpe != &tmpm->header && *count > 0) {
vm_pageout_map_deactivate_pages(tmpm, tmpe, count, freeer);
tmpe = tmpe->next;
};
} else if ((obj = entry->object.vm_object) != 0) {
*count -= (*freeer)(map, obj, *count);
}
lock_read_done(&map->lock);
vm_map_deallocate(map);
return;
}
void
vm_req_vmdaemon() {
extern int ticks;
static lastrun = 0;
if( (ticks > (lastrun + hz/10)) || (ticks < lastrun)) {
wakeup((caddr_t) &vm_daemon_needed);
lastrun = ticks;
}
}
/*
* vm_pageout_scan does the dirty work for the pageout daemon.
*/
int
vm_pageout_scan()
{
vm_page_t m;
int page_shortage, maxscan, maxlaunder;
int pages_freed;
int desired_free;
vm_page_t next;
struct proc *p, *bigproc;
vm_offset_t size, bigsize;
vm_object_t object;
int force_wakeup = 0;
int cache_size, orig_cache_size;
/* calculate the total cached size */
if( cnt.v_inactive_count < cnt.v_inactive_target) {
vm_req_vmdaemon();
}
morefree:
/*
* now swap processes out if we are in low memory conditions
*/
if ((cnt.v_free_count <= cnt.v_free_min) && !swap_pager_full && vm_swap_size&& vm_pageout_req_swapout == 0) {
vm_pageout_req_swapout = 1;
vm_req_vmdaemon();
}
pages_freed = 0;
desired_free = cnt.v_free_target;
/*
* Start scanning the inactive queue for pages we can free.
* We keep scanning until we have enough free pages or
* we have scanned through the entire queue. If we
* encounter dirty pages, we start cleaning them.
*/
maxlaunder = 128;
maxscan = cnt.v_inactive_count;
rescan1:
m = vm_page_queue_inactive.tqh_first;
while (m && (maxscan-- > 0) &&
(cnt.v_free_count < desired_free) ) {
vm_page_t next;
cnt.v_pdpages++;
next = m->pageq.tqe_next;
if( (m->flags & PG_INACTIVE) == 0) {
printf("vm_pageout_scan: page not inactive?");
continue;
}
/*
* activate held pages
*/
if (m->hold_count != 0) {
vm_page_activate(m);
m = next;
continue;
}
/*
* dont mess with busy pages
*/
if (m->busy || (m->flags & PG_BUSY)) {
m = next;
continue;
}
if (((m->flags & PG_CLEAN) != 0) && pmap_is_modified(VM_PAGE_TO_PHYS(m))) {
m->flags &= ~PG_CLEAN;
m->flags |= PG_LAUNDRY;
}
if (((m->flags & PG_REFERENCED) == 0) && pmap_is_referenced(VM_PAGE_TO_PHYS(m))) {
m->flags |= PG_REFERENCED;
pmap_clear_reference(VM_PAGE_TO_PHYS(m));
}
if (m->flags & PG_CLEAN) {
/*
* If we're not low on memory and the page has been reference,
* then reactivate the page.
*/
if ((cnt.v_free_count > vm_pageout_free_min) &&
((m->flags & PG_REFERENCED) != 0)) {
m->flags &= ~PG_REFERENCED;
vm_page_activate(m);
} else if (m->act_count == 0) {
pmap_page_protect(VM_PAGE_TO_PHYS(m),
VM_PROT_NONE);
vm_page_free(m);
++cnt.v_dfree;
++pages_freed;
} else {
m->act_count -= min(m->act_count, ACT_DECLINE);
TAILQ_REMOVE(&vm_page_queue_inactive, m, pageq);
TAILQ_INSERT_TAIL(&vm_page_queue_inactive, m, pageq);
}
} else if ((m->flags & PG_LAUNDRY) && maxlaunder > 0) {
int written;
if ((m->flags & PG_REFERENCED) != 0) {
m->flags &= ~PG_REFERENCED;
vm_page_activate(m);
m = next;
continue;
}
/*
* If a page is dirty, then it is either
* being washed (but not yet cleaned)
* or it is still in the laundry. If it is
* still in the laundry, then we start the
* cleaning operation.
*/
written = vm_pageout_clean(m,0);
if (written)
maxlaunder -= written;
if (!next)
break;
/*
* if the next page has been re-activated, start scanning again
*/
if ((written != 0) || ((next->flags & PG_INACTIVE) == 0))
goto rescan1;
} else if ((m->flags & PG_REFERENCED) != 0) {
m->flags &= ~PG_REFERENCED;
vm_page_activate(m);
}
m = next;
}
/*
* Compute the page shortage. If we are still very low on memory
* be sure that we will move a minimal amount of pages from active
* to inactive.
*/
page_shortage = cnt.v_inactive_target -
(cnt.v_free_count + cnt.v_inactive_count);
if (page_shortage <= 0) {
if (pages_freed == 0) {
if( cnt.v_free_count < cnt.v_free_min) {
page_shortage = cnt.v_free_min - cnt.v_free_count + 1;
} else if(((cnt.v_free_count + cnt.v_inactive_count) <
(cnt.v_free_min + cnt.v_inactive_target))) {
page_shortage = 1;
} else {
page_shortage = 0;
}
}
}
maxscan = cnt.v_active_count;
m = vm_page_queue_active.tqh_first;
while (m && maxscan-- && (page_shortage > 0)) {
cnt.v_pdpages++;
next = m->pageq.tqe_next;
/*
* Don't deactivate pages that are busy.
*/
if ((m->busy != 0) ||
(m->flags & PG_BUSY) || (m->hold_count != 0)) {
m = next;
continue;
}
if ((m->flags & PG_REFERENCED) ||
pmap_is_referenced(VM_PAGE_TO_PHYS(m))) {
pmap_clear_reference(VM_PAGE_TO_PHYS(m));
m->flags &= ~PG_REFERENCED;
if (m->act_count < ACT_MAX)
m->act_count += ACT_ADVANCE;
TAILQ_REMOVE(&vm_page_queue_active, m, pageq);
TAILQ_INSERT_TAIL(&vm_page_queue_active, m, pageq);
TAILQ_REMOVE(&m->object->memq, m, listq);
TAILQ_INSERT_TAIL(&m->object->memq, m, listq);
} else {
m->act_count -= min(m->act_count, ACT_DECLINE);
/*
* if the page act_count is zero -- then we deactivate
*/
if (!m->act_count) {
vm_page_deactivate(m);
--page_shortage;
/*
* else if on the next go-around we will deactivate the page
* we need to place the page on the end of the queue to age
* the other pages in memory.
*/
} else {
TAILQ_REMOVE(&vm_page_queue_active, m, pageq);
TAILQ_INSERT_TAIL(&vm_page_queue_active, m, pageq);
TAILQ_REMOVE(&m->object->memq, m, listq);
TAILQ_INSERT_TAIL(&m->object->memq, m, listq);
}
}
m = next;
}
/*
* if we have not freed any pages and we are desparate for memory
* then we keep trying until we get some (any) memory.
*/
if (!force_wakeup && (swap_pager_full || !force_wakeup ||
(pages_freed == 0 && (cnt.v_free_count < cnt.v_free_min)))){
vm_pager_sync();
force_wakeup = 1;
goto morefree;
}
/*
* make sure that we have swap space -- if we are low on
* memory and swap -- then kill the biggest process.
*/
if ((vm_swap_size == 0 || swap_pager_full) &&
(cnt.v_free_count < cnt.v_free_min)) {
bigproc = NULL;
bigsize = 0;
for (p = (struct proc *)allproc; p != NULL; p = p->p_next) {
/*
* if this is a system process, skip it
*/
if ((p->p_flag & P_SYSTEM) || (p->p_pid == 1) ||
((p->p_pid < 48) && (vm_swap_size != 0))) {
continue;
}
/*
* if the process is in a non-running type state,
* don't touch it.
*/
if (p->p_stat != SRUN && p->p_stat != SSLEEP) {
continue;
}
/*
* get the process size
*/
size = p->p_vmspace->vm_pmap.pm_stats.resident_count;
/*
* if the this process is bigger than the biggest one
* remember it.
*/
if (size > bigsize) {
bigproc = p;
bigsize = size;
}
}
if (bigproc != NULL) {
printf("Process %lu killed by vm_pageout -- out of swap\n", (u_long)bigproc->p_pid);
psignal(bigproc, SIGKILL);
bigproc->p_estcpu = 0;
bigproc->p_nice = PRIO_MIN;
resetpriority(bigproc);
wakeup( (caddr_t) &cnt.v_free_count);
}
}
vm_page_pagesfreed += pages_freed;
return force_wakeup;
}
/*
* vm_pageout is the high level pageout daemon.
*/
void
vm_pageout()
{
(void) spl0();
/*
* Initialize some paging parameters.
*/
cnt.v_free_min = 12;
/*
* free_reserved needs to include enough for the largest
* swap pager structures plus enough for any pv_entry
* structs when paging.
*/
vm_pageout_free_min = 4 + cnt.v_page_count / 1024;
cnt.v_free_reserved = vm_pageout_free_min + 2;
if (cnt.v_free_min < 8)
cnt.v_free_min = 8;
if (cnt.v_free_min > 32)
cnt.v_free_min = 32;
cnt.v_free_target = 2*cnt.v_free_min + cnt.v_free_reserved;
cnt.v_inactive_target = cnt.v_free_count / 12;
cnt.v_free_min += cnt.v_free_reserved;
vm_desired_cache_size = cnt.v_page_count / 3;
/* XXX does not really belong here */
if (vm_page_max_wired == 0)
vm_page_max_wired = cnt.v_free_count / 3;
(void) swap_pager_alloc(0, 0, 0, 0);
/*
* The pageout daemon is never done, so loop
* forever.
*/
while (TRUE) {
int force_wakeup;
tsleep((caddr_t) &vm_pages_needed, PVM, "psleep", 0);
cnt.v_pdwakeups++;
vm_pager_sync();
/*
* The force wakeup hack added to eliminate delays and potiential
* deadlock. It was possible for the page daemon to indefintely
* postpone waking up a process that it might be waiting for memory
* on. The putmulti stuff seems to have aggravated the situation.
*/
force_wakeup = vm_pageout_scan();
vm_pager_sync();
if( force_wakeup)
wakeup( (caddr_t) &cnt.v_free_count);
wakeup((caddr_t) kmem_map);
}
}
void
vm_daemon() {
int cache_size;
vm_object_t object;
struct proc *p;
while(TRUE) {
tsleep((caddr_t) &vm_daemon_needed, PUSER, "psleep", 0);
if( vm_pageout_req_swapout) {
/*
* swap out inactive processes
*/
swapout_threads();
vm_pageout_req_swapout = 0;
}
/*
* scan the processes for exceeding their rlimits or if process
* is swapped out -- deactivate pages
*/
for (p = (struct proc *)allproc; p != NULL; p = p->p_next) {
int overage;
quad_t limit;
vm_offset_t size;
/*
* if this is a system process or if we have already
* looked at this process, skip it.
*/
if (p->p_flag & (P_SYSTEM|P_WEXIT)) {
continue;
}
/*
* if the process is in a non-running type state,
* don't touch it.
*/
if (p->p_stat != SRUN && p->p_stat != SSLEEP) {
continue;
}
/*
* get a limit
*/
limit = qmin(p->p_rlimit[RLIMIT_RSS].rlim_cur,
p->p_rlimit[RLIMIT_RSS].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;
size = p->p_vmspace->vm_pmap.pm_stats.resident_count * NBPG;
if (limit >= 0 && size >= limit) {
overage = (size - limit) / NBPG;
vm_pageout_map_deactivate_pages(&p->p_vmspace->vm_map,
(vm_map_entry_t) 0, &overage, vm_pageout_object_deactivate_pages);
}
}
/*
* We manage the cached memory by attempting to keep it
* at about the desired level.
* We deactivate the pages for the oldest cached objects
* first. This keeps pages that are "cached" from hogging
* physical memory.
*/
restart:
cache_size = 0;
object = vm_object_cached_list.tqh_first;
/* calculate the total cached size */
while( object) {
cache_size += object->resident_page_count;
object = object->cached_list.tqe_next;
}
vm_object_cache_lock();
object = vm_object_cached_list.tqh_first;
while ( object) {
vm_object_cache_unlock();
/*
* if there are no resident pages -- get rid of the object
*/
if( object->resident_page_count == 0) {
if (object != vm_object_lookup(object->pager))
panic("vm_object_cache_trim: I'm sooo confused.");
pager_cache(object, FALSE);
goto restart;
} else if( cache_size >= (vm_swap_size?vm_desired_cache_size:0)) {
/*
* if there are resident pages -- deactivate them
*/
vm_object_deactivate_pages(object);
cache_size -= object->resident_page_count;
}
object = object->cached_list.tqe_next;
vm_object_cache_lock();
}
vm_object_cache_unlock();
}
}
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