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freebsd-dev/sys/vm/vm_pageout.c
David Greenman 24a1cce34f NOTE: libkvm, w, ps, 'top', and any other utility which depends on struct 
proc or any VM system structure will have to be rebuilt!!!

Much needed overhaul of the VM system. Included in this first round of
changes:

1) Improved pager interfaces: init, alloc, dealloc, getpages, putpages,
   haspage, and sync operations are supported. The haspage interface now
   provides information about clusterability. All pager routines now take
   struct vm_object's instead of "pagers".

2) Improved data structures. In the previous paradigm, there is constant
   confusion caused by pagers being both a data structure ("allocate a
   pager") and a collection of routines. The idea of a pager structure has
   escentially been eliminated. Objects now have types, and this type is
   used to index the appropriate pager. In most cases, items in the pager
   structure were duplicated in the object data structure and thus were
   unnecessary. In the few cases that remained, a un_pager structure union
   was created in the object to contain these items.

3) Because of the cleanup of #1 & #2, a lot of unnecessary layering can now
   be removed. For instance, vm_object_enter(), vm_object_lookup(),
   vm_object_remove(), and the associated object hash list were some of the
   things that were removed.

4) simple_lock's removed. Discussion with several people reveals that the
   SMP locking primitives used in the VM system aren't likely the mechanism
   that we'll be adopting. Even if it were, the locking that was in the code
   was very inadequate and would have to be mostly re-done anyway. The
   locking in a uni-processor kernel was a no-op but went a long way toward
   making the code difficult to read and debug.

5) Places that attempted to kludge-up the fact that we don't have kernel
   thread support have been fixed to reflect the reality that we are really
   dealing with processes, not threads. The VM system didn't have complete
   thread support, so the comments and mis-named routines were just wrong.
   We now use tsleep and wakeup directly in the lock routines, for instance.

6) Where appropriate, the pagers have been improved, especially in the
   pager_alloc routines. Most of the pager_allocs have been rewritten and
   are now faster and easier to maintain.

7) The pagedaemon pageout clustering algorithm has been rewritten and
   now tries harder to output an even number of pages before and after
   the requested page. This is sort of the reverse of the ideal pagein
   algorithm and should provide better overall performance.

8) Unnecessary (incorrect) casts to caddr_t in calls to tsleep & wakeup
   have been removed. Some other unnecessary casts have also been removed.

9) Some almost useless debugging code removed.

10) Terminology of shadow objects vs. backing objects straightened out.
    The fact that the vm_object data structure escentially had this
    backwards really confused things. The use of "shadow" and "backing
    object" throughout the code is now internally consistent and correct
    in the Mach terminology.

11) Several minor bug fixes, including one in the vm daemon that caused
    0 RSS objects to not get purged as intended.

12) A "default pager" has now been created which cleans up the transition
    of objects to the "swap" type. The previous checks throughout the code
    for swp->pg_data != NULL were really ugly. This change also provides
    the rudiments for future backing of "anonymous" memory by something
    other than the swap pager (via the vnode pager, for example), and it
    allows the decision about which of these pagers to use to be made
    dynamically (although will need some additional decision code to do
    this, of course).

13) (dyson) MAP_COPY has been deprecated and the corresponding "copy
    object" code has been removed. MAP_COPY was undocumented and non-
    standard. It was furthermore broken in several ways which caused its
    behavior to degrade to MAP_PRIVATE. Binaries that use MAP_COPY will
    continue to work correctly, but via the slightly different semantics
    of MAP_PRIVATE.

14) (dyson) Sharing maps have been removed. It's marginal usefulness in a
    threads design can be worked around in other ways. Both #12 and #13
    were done to simplify the code and improve readability and maintain-
    ability. (As were most all of these changes)

TODO:

1) Rewrite most of the vnode pager to use VOP_GETPAGES/PUTPAGES. Doing
   this will reduce the vnode pager to a mere fraction of its current size.

2) Rewrite vm_fault and the swap/vnode pagers to use the clustering
   information provided by the new haspage pager interface. This will
   substantially reduce the overhead by eliminating a large number of
   VOP_BMAP() calls. The VOP_BMAP() filesystem interface should be
   improved to provide both a "behind" and "ahead" indication of
   contiguousness.

3) Implement the extended features of pager_haspage in swap_pager_haspage().
   It currently just says 0 pages ahead/behind.

4) Re-implement the swap device (swstrategy) in a more elegant way, perhaps
   via a much more general mechanism that could also be used for disk
   striping of regular filesystems.

5) Do something to improve the architecture of vm_object_collapse(). The
   fact that it makes calls into the swap pager and knows too much about
   how the swap pager operates really bothers me. It also doesn't allow
   for collapsing of non-swap pager objects ("unnamed" objects backed by
   other pagers).
1995-07-13 08:48:48 +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 1.52 1995/07/10 08:53:22 davidg Exp $
*/
/*
* The proverbial page-out daemon.
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/proc.h>
#include <sys/resourcevar.h>
#include <sys/malloc.h>
#include <sys/kernel.h>
#include <sys/signalvar.h>
#include <sys/vnode.h>
#include <vm/vm.h>
#include <vm/vm_page.h>
#include <vm/vm_pageout.h>
#include <vm/vm_kern.h>
#include <vm/vm_pager.h>
#include <vm/swap_pager.h>
int vm_pages_needed; /* Event on which pageout daemon sleeps */
int vm_pageout_pages_needed; /* flag saying that the pageout daemon needs pages */
extern int npendingio;
int vm_pageout_req_swapout; /* XXX */
int vm_daemon_needed;
extern int nswiodone;
extern int swap_pager_full;
extern int vm_swap_size;
extern int vfs_update_wakeup;
#define MAXSCAN 1024 /* maximum number of pages to scan in queues */
#define MAXLAUNDER (cnt.v_page_count > 1800 ? 32 : 16)
#define VM_PAGEOUT_PAGE_COUNT 8
int vm_pageout_page_count = VM_PAGEOUT_PAGE_COUNT;
int vm_page_max_wired; /* XXX max # of wired pages system-wide */
/*
* vm_pageout_clean:
*
* 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!)
*/
int
vm_pageout_clean(m, sync)
vm_page_t m;
int sync;
{
register vm_object_t object;
int pageout_status[VM_PAGEOUT_PAGE_COUNT];
vm_page_t mc[2*VM_PAGEOUT_PAGE_COUNT];
int pageout_count;
int anyok = 0;
int i, forward_okay, backward_okay, page_base;
vm_offset_t offset = m->offset;
object = m->object;
/*
* If not OBJT_SWAP, additional memory may be needed to do the pageout.
* Try to avoid the deadlock.
*/
if ((sync != VM_PAGEOUT_FORCE) &&
(object->type != OBJT_SWAP) &&
((cnt.v_free_count + cnt.v_cache_count) < cnt.v_pageout_free_min))
return 0;
/*
* Don't mess with the page if it's busy.
*/
if ((!sync && m->hold_count != 0) ||
((m->busy != 0) || (m->flags & PG_BUSY)))
return 0;
/*
* Try collapsing before it's too late.
*/
if (!sync && object->backing_object) {
vm_object_collapse(object);
}
mc[VM_PAGEOUT_PAGE_COUNT] = m;
pageout_count = 1;
page_base = VM_PAGEOUT_PAGE_COUNT;
forward_okay = TRUE;
if (offset != 0)
backward_okay = TRUE;
else
backward_okay = FALSE;
/*
* Scan object for clusterable pages.
*
* We can cluster ONLY if: ->> the page is NOT
* clean, wired, busy, held, or mapped into a
* buffer, and one of the following:
* 1) The page is inactive, or a seldom used
* active page.
* -or-
* 2) we force the issue.
*/
for (i = 1; (i < vm_pageout_page_count) && (forward_okay || backward_okay); i++) {
vm_page_t p;
/*
* See if forward page is clusterable.
*/
if (forward_okay) {
/*
* Stop forward scan at end of object.
*/
if ((offset + i * PAGE_SIZE) > object->size) {
forward_okay = FALSE;
goto do_backward;
}
p = vm_page_lookup(object, offset + i * PAGE_SIZE);
if (p) {
if ((p->flags & (PG_BUSY|PG_CACHE)) || p->busy) {
forward_okay = FALSE;
goto do_backward;
}
vm_page_test_dirty(p);
if ((p->dirty & p->valid) != 0 &&
((p->flags & PG_INACTIVE) ||
(sync == VM_PAGEOUT_FORCE)) &&
(p->wire_count == 0) &&
(p->hold_count == 0)) {
mc[VM_PAGEOUT_PAGE_COUNT + i] = p;
pageout_count++;
if (pageout_count == vm_pageout_page_count)
break;
} else {
forward_okay = FALSE;
}
} else {
forward_okay = FALSE;
}
}
do_backward:
/*
* See if backward page is clusterable.
*/
if (backward_okay) {
/*
* Stop backward scan at beginning of object.
*/
if ((offset - i * PAGE_SIZE) == 0) {
backward_okay = FALSE;
}
p = vm_page_lookup(object, offset - i * PAGE_SIZE);
if (p) {
if ((p->flags & (PG_BUSY|PG_CACHE)) || p->busy) {
backward_okay = FALSE;
continue;
}
vm_page_test_dirty(p);
if ((p->dirty & p->valid) != 0 &&
((p->flags & PG_INACTIVE) ||
(sync == VM_PAGEOUT_FORCE)) &&
(p->wire_count == 0) &&
(p->hold_count == 0)) {
mc[VM_PAGEOUT_PAGE_COUNT - i] = p;
pageout_count++;
page_base--;
if (pageout_count == vm_pageout_page_count)
break;
} else {
backward_okay = FALSE;
}
} else {
backward_okay = FALSE;
}
}
}
/*
* we allow reads during pageouts...
*/
for (i = page_base; i < (page_base + pageout_count); i++) {
mc[i]->flags |= PG_BUSY;
vm_page_protect(mc[i], VM_PROT_READ);
}
object->paging_in_progress += pageout_count;
vm_pager_put_pages(object, &mc[page_base], pageout_count,
((sync || (object == kernel_object)) ? TRUE : FALSE),
pageout_status);
for (i = 0; i < pageout_count; i++) {
vm_page_t mt = mc[page_base + i];
switch (pageout_status[i]) {
case VM_PAGER_OK:
++anyok;
break;
case VM_PAGER_PEND:
++anyok;
break;
case VM_PAGER_BAD:
/*
* Page outside of range of object. Right now we
* essentially lose the changes by pretending it
* worked.
*/
pmap_clear_modify(VM_PAGE_TO_PHYS(mt));
mt->dirty = 0;
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 (mt->flags & PG_INACTIVE)
vm_page_activate(mt);
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) {
vm_object_pip_wakeup(object);
if ((mt->flags & (PG_REFERENCED|PG_WANTED)) ||
pmap_is_referenced(VM_PAGE_TO_PHYS(mt))) {
pmap_clear_reference(VM_PAGE_TO_PHYS(mt));
mt->flags &= ~PG_REFERENCED;
if (mt->flags & PG_INACTIVE)
vm_page_activate(mt);
}
PAGE_WAKEUP(mt);
}
}
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
* backing_objects.
*
* The object and map must be locked.
*/
int
vm_pageout_object_deactivate_pages(map, object, count, map_remove_only)
vm_map_t map;
vm_object_t object;
int count;
int map_remove_only;
{
register vm_page_t p, next;
int rcount;
int dcount;
dcount = 0;
if (count == 0)
count = 1;
if (object->type == OBJT_DEVICE)
return 0;
if (object->backing_object) {
if (object->backing_object->ref_count == 1)
dcount += vm_pageout_object_deactivate_pages(map,
object->backing_object, count / 2 + 1, map_remove_only);
else
vm_pageout_object_deactivate_pages(map,
object->backing_object, count, 1);
}
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++;
if (p->wire_count != 0 ||
p->hold_count != 0 ||
p->busy != 0 ||
!pmap_page_exists(vm_map_pmap(map), VM_PAGE_TO_PHYS(p))) {
p = next;
continue;
}
/*
* 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) {
if (!pmap_is_referenced(VM_PAGE_TO_PHYS(p)) &&
(p->flags & (PG_REFERENCED|PG_WANTED)) == 0) {
p->act_count -= min(p->act_count, ACT_DECLINE);
/*
* if the page act_count is zero -- then we
* deactivate
*/
if (!p->act_count) {
if (!map_remove_only)
vm_page_deactivate(p);
vm_page_protect(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);
}
/*
* see if we are done yet
*/
if (p->flags & PG_INACTIVE) {
--count;
++dcount;
if (count <= 0 &&
cnt.v_inactive_count > cnt.v_inactive_target) {
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);
}
} else if ((p->flags & (PG_INACTIVE | PG_BUSY)) == PG_INACTIVE) {
vm_page_protect(p, VM_PROT_NONE);
}
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, 0);
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, 0);
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()
{
static int lastrun = 0;
if ((ticks > (lastrun + hz / 10)) || (ticks < lastrun)) {
wakeup(&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, pcount;
int pages_freed;
vm_page_t next;
struct proc *p, *bigproc;
vm_offset_t size, bigsize;
vm_object_t object;
int force_wakeup = 0;
int vnodes_skipped = 0;
pages_freed = 0;
/*
* 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 = (cnt.v_inactive_target > MAXLAUNDER) ?
MAXLAUNDER : cnt.v_inactive_target;
rescan1:
maxscan = cnt.v_inactive_count;
m = vm_page_queue_inactive.tqh_first;
while ((m != NULL) && (maxscan-- > 0) &&
((cnt.v_cache_count + cnt.v_free_count) < (cnt.v_cache_min + cnt.v_free_target))) {
vm_page_t next;
cnt.v_pdpages++;
next = m->pageq.tqe_next;
#if defined(VM_DIAGNOSE)
if ((m->flags & PG_INACTIVE) == 0) {
printf("vm_pageout_scan: page not inactive?\n");
break;
}
#endif
/*
* dont mess with busy pages
*/
if (m->hold_count || m->busy || (m->flags & PG_BUSY)) {
TAILQ_REMOVE(&vm_page_queue_inactive, m, pageq);
TAILQ_INSERT_TAIL(&vm_page_queue_inactive, m, pageq);
m = next;
continue;
}
if (((m->flags & PG_REFERENCED) == 0) &&
pmap_is_referenced(VM_PAGE_TO_PHYS(m))) {
m->flags |= PG_REFERENCED;
}
if (m->object->ref_count == 0) {
m->flags &= ~PG_REFERENCED;
pmap_clear_reference(VM_PAGE_TO_PHYS(m));
}
if ((m->flags & (PG_REFERENCED|PG_WANTED)) != 0) {
m->flags &= ~PG_REFERENCED;
pmap_clear_reference(VM_PAGE_TO_PHYS(m));
vm_page_activate(m);
if (m->act_count < ACT_MAX)
m->act_count += ACT_ADVANCE;
m = next;
continue;
}
vm_page_test_dirty(m);
if (m->dirty == 0) {
if (m->bmapped == 0) {
if (m->valid == 0) {
pmap_page_protect(VM_PAGE_TO_PHYS(m), VM_PROT_NONE);
vm_page_free(m);
cnt.v_dfree++;
} else {
vm_page_cache(m);
}
++pages_freed;
} else {
m = next;
continue;
}
} else if (maxlaunder > 0) {
int written;
struct vnode *vp = NULL;
object = m->object;
if (object->flags & OBJ_DEAD) {
m = next;
continue;
}
if (object->type == OBJT_VNODE) {
vp = object->handle;
if (VOP_ISLOCKED(vp) || vget(vp, 1)) {
if (object->flags & OBJ_WRITEABLE)
++vnodes_skipped;
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 (vp)
vput(vp);
if (!next) {
break;
}
maxlaunder -= written;
/*
* if the next page has been re-activated, start
* scanning again
*/
if ((next->flags & PG_INACTIVE) == 0) {
goto rescan1;
}
}
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 + cnt.v_cache_count);
if (page_shortage <= 0) {
if (pages_freed == 0) {
page_shortage = cnt.v_free_min - cnt.v_free_count;
} else {
page_shortage = 1;
}
}
maxscan = MAXSCAN;
pcount = cnt.v_active_count;
m = vm_page_queue_active.tqh_first;
while ((m != NULL) && (maxscan > 0) && (pcount-- > 0) && (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)) {
TAILQ_REMOVE(&vm_page_queue_active, m, pageq);
TAILQ_INSERT_TAIL(&vm_page_queue_active, m, pageq);
m = next;
continue;
}
if (m->object->ref_count && ((m->flags & (PG_REFERENCED|PG_WANTED)) ||
pmap_is_referenced(VM_PAGE_TO_PHYS(m)))) {
int s;
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);
} else {
m->flags &= ~PG_REFERENCED;
pmap_clear_reference(VM_PAGE_TO_PHYS(m));
m->act_count -= min(m->act_count, ACT_DECLINE);
/*
* if the page act_count is zero -- then we deactivate
*/
if (!m->act_count && (page_shortage > 0)) {
if (m->object->ref_count == 0) {
--page_shortage;
vm_page_test_dirty(m);
if ((m->bmapped == 0) && (m->dirty == 0) ) {
m->act_count = 0;
vm_page_cache(m);
} else {
vm_page_deactivate(m);
}
} else {
vm_page_deactivate(m);
--page_shortage;
}
} else if (m->act_count) {
TAILQ_REMOVE(&vm_page_queue_active, m, pageq);
TAILQ_INSERT_TAIL(&vm_page_queue_active, m, pageq);
}
}
maxscan--;
m = next;
}
/*
* We try to maintain some *really* free pages, this allows interrupt
* code to be guaranteed space.
*/
while (cnt.v_free_count < cnt.v_free_reserved) {
m = vm_page_queue_cache.tqh_first;
if (!m)
break;
vm_page_free(m);
cnt.v_dfree++;
}
/*
* If we didn't get enough free pages, and we have skipped a vnode
* in a writeable object, wakeup the sync daemon. And kick swapout
* if we did not get enough free pages.
*/
if ((cnt.v_cache_count + cnt.v_free_count) < cnt.v_free_target) {
if (vnodes_skipped &&
(cnt.v_cache_count + cnt.v_free_count) < cnt.v_free_min) {
if (!vfs_update_wakeup) {
vfs_update_wakeup = 1;
wakeup(&vfs_update_wakeup);
}
}
/*
* now swap processes out if we are in low memory conditions
*/
if (!swap_pager_full && vm_swap_size &&
vm_pageout_req_swapout == 0) {
vm_pageout_req_swapout = 1;
vm_req_vmdaemon();
}
}
if ((cnt.v_inactive_count + cnt.v_free_count + cnt.v_cache_count) <
(cnt.v_inactive_target + cnt.v_free_min)) {
vm_req_vmdaemon();
}
/*
* 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_cache_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(&cnt.v_free_count);
}
}
return force_wakeup;
}
/*
* vm_pageout is the high level pageout daemon.
*/
void
vm_pageout()
{
(void) spl0();
/*
* Initialize some paging parameters.
*/
cnt.v_interrupt_free_min = 2;
if (cnt.v_page_count > 1024)
cnt.v_free_min = 4 + (cnt.v_page_count - 1024) / 200;
else
cnt.v_free_min = 4;
/*
* free_reserved needs to include enough for the largest swap pager
* structures plus enough for any pv_entry structs when paging.
*/
cnt.v_pageout_free_min = 6 + cnt.v_page_count / 1024 +
cnt.v_interrupt_free_min;
cnt.v_free_reserved = cnt.v_pageout_free_min + 6;
cnt.v_free_target = 3 * cnt.v_free_min + cnt.v_free_reserved;
cnt.v_free_min += cnt.v_free_reserved;
if (cnt.v_page_count > 1024) {
cnt.v_cache_max = (cnt.v_free_count - 1024) / 2;
cnt.v_cache_min = (cnt.v_free_count - 1024) / 8;
cnt.v_inactive_target = 2*cnt.v_cache_min + 192;
} else {
cnt.v_cache_min = 0;
cnt.v_cache_max = 0;
cnt.v_inactive_target = cnt.v_free_count / 4;
}
/* XXX does not really belong here */
if (vm_page_max_wired == 0)
vm_page_max_wired = cnt.v_free_count / 3;
swap_pager_swap_init();
/*
* The pageout daemon is never done, so loop forever.
*/
while (TRUE) {
int s = splhigh();
if (!vm_pages_needed ||
((cnt.v_free_count >= cnt.v_free_reserved) &&
(cnt.v_free_count + cnt.v_cache_count >= cnt.v_free_min))) {
vm_pages_needed = 0;
tsleep(&vm_pages_needed, PVM, "psleep", 0);
}
vm_pages_needed = 0;
splx(s);
cnt.v_pdwakeups++;
vm_pager_sync();
vm_pageout_scan();
vm_pager_sync();
wakeup(&cnt.v_free_count);
wakeup(kmem_map);
}
}
void
vm_daemon()
{
vm_object_t object;
struct proc *p;
while (TRUE) {
tsleep(&vm_daemon_needed, PUSER, "psleep", 0);
if (vm_pageout_req_swapout) {
swapout_procs();
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; /* XXX */
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 remove cached objects that have no RSS...
*/
restart:
object = vm_object_cached_list.tqh_first;
while (object) {
/*
* if there are no resident pages -- get rid of the object
*/
if (object->resident_page_count == 0) {
vm_object_reference(object);
pager_cache(object, FALSE);
goto restart;
}
object = object->cached_list.tqe_next;
}
}
}
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