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freebsd-dev/sys/vm/vm_object.c
David Greenman 46268a606f Revert to previous calculation of vm_object_cache_max: it simply works 
better in most real-world cases.
1996-03-29 06:28:48 +00:00

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/*
* Copyright (c) 1991, 1993
* The Regents of the University of California. 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_object.c 8.5 (Berkeley) 3/22/94
*
*
* 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_object.c,v 1.66 1996/03/28 04:53:26 dyson Exp $
*/
/*
* Virtual memory object module.
*/
#include "opt_ddb.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/proc.h> /* for curproc, pageproc */
#include <sys/malloc.h>
#include <sys/vnode.h>
#include <sys/mount.h>
#include <sys/vmmeter.h>
#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/vm_prot.h>
#include <vm/lock.h>
#include <vm/pmap.h>
#include <vm/vm_map.h>
#include <vm/vm_object.h>
#include <vm/vm_page.h>
#include <vm/vm_pageout.h>
#include <vm/vm_pager.h>
#include <vm/swap_pager.h>
#include <vm/vm_kern.h>
#include <vm/vm_extern.h>
#ifdef DDB
static void DDB_vm_object_check __P((void));
#endif
static void _vm_object_allocate __P((objtype_t, vm_size_t, vm_object_t));
#ifdef DDB
static int _vm_object_in_map __P((vm_map_t map, vm_object_t object,
vm_map_entry_t entry));
static int vm_object_in_map __P((vm_object_t object));
#endif
static void vm_object_qcollapse __P((vm_object_t object));
#ifdef not_used
static void vm_object_deactivate_pages __P((vm_object_t));
#endif
static void vm_object_terminate __P((vm_object_t));
static void vm_object_cache_trim __P((void));
/*
* Virtual memory objects maintain the actual data
* associated with allocated virtual memory. A given
* page of memory exists within exactly one object.
*
* An object is only deallocated when all "references"
* are given up. Only one "reference" to a given
* region of an object should be writeable.
*
* Associated with each object is a list of all resident
* memory pages belonging to that object; this list is
* maintained by the "vm_page" module, and locked by the object's
* lock.
*
* Each object also records a "pager" routine which is
* used to retrieve (and store) pages to the proper backing
* storage. In addition, objects may be backed by other
* objects from which they were virtual-copied.
*
* The only items within the object structure which are
* modified after time of creation are:
* reference count locked by object's lock
* pager routine locked by object's lock
*
*/
int vm_object_cache_max;
struct object_q vm_object_cached_list;
static int vm_object_cached;
struct object_q vm_object_list;
static long vm_object_count;
vm_object_t kernel_object;
vm_object_t kmem_object;
static struct vm_object kernel_object_store;
static struct vm_object kmem_object_store;
extern int vm_pageout_page_count;
static long object_collapses;
static long object_bypasses;
static void
_vm_object_allocate(type, size, object)
objtype_t type;
vm_size_t size;
register vm_object_t object;
{
TAILQ_INIT(&object->memq);
TAILQ_INIT(&object->shadow_head);
object->type = type;
object->size = size;
object->ref_count = 1;
object->flags = 0;
object->paging_in_progress = 0;
object->resident_page_count = 0;
object->shadow_count = 0;
object->handle = NULL;
object->paging_offset = (vm_ooffset_t) 0;
object->backing_object = NULL;
object->backing_object_offset = (vm_ooffset_t) 0;
object->last_read = 0;
TAILQ_INSERT_TAIL(&vm_object_list, object, object_list);
vm_object_count++;
}
/*
* vm_object_init:
*
* Initialize the VM objects module.
*/
void
vm_object_init()
{
TAILQ_INIT(&vm_object_cached_list);
TAILQ_INIT(&vm_object_list);
vm_object_count = 0;
vm_object_cache_max = 84;
if (cnt.v_page_count > 1000)
vm_object_cache_max += (cnt.v_page_count - 1000) / 4;
kernel_object = &kernel_object_store;
_vm_object_allocate(OBJT_DEFAULT, OFF_TO_IDX(VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS),
kernel_object);
kmem_object = &kmem_object_store;
_vm_object_allocate(OBJT_DEFAULT, OFF_TO_IDX(VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS),
kmem_object);
}
/*
* vm_object_allocate:
*
* Returns a new object with the given size.
*/
vm_object_t
vm_object_allocate(type, size)
objtype_t type;
vm_size_t size;
{
register vm_object_t result;
result = (vm_object_t)
malloc((u_long) sizeof *result, M_VMOBJ, M_WAITOK);
_vm_object_allocate(type, size, result);
return (result);
}
/*
* vm_object_reference:
*
* Gets another reference to the given object.
*/
inline void
vm_object_reference(object)
register vm_object_t object;
{
if (object == NULL)
return;
if (object->ref_count == 0) {
if ((object->flags & OBJ_CANPERSIST) == 0)
panic("vm_object_reference: non-persistent object with 0 ref_count");
TAILQ_REMOVE(&vm_object_cached_list, object, cached_list);
vm_object_cached--;
}
object->ref_count++;
}
/*
* vm_object_deallocate:
*
* Release a reference to the specified object,
* gained either through a vm_object_allocate
* or a vm_object_reference call. When all references
* are gone, storage associated with this object
* may be relinquished.
*
* No object may be locked.
*/
void
vm_object_deallocate(object)
vm_object_t object;
{
vm_object_t temp;
vm_page_t p;
while (object != NULL) {
if (object->ref_count == 0)
panic("vm_object_deallocate: object deallocated too many times");
/*
* Lose the reference
*/
object->ref_count--;
if (object->ref_count != 0) {
if ((object->ref_count == 1) &&
(object->handle == NULL) &&
(object->type == OBJT_DEFAULT ||
object->type == OBJT_SWAP)) {
vm_object_t robject;
robject = object->shadow_head.tqh_first;
if ((robject != NULL) &&
(robject->handle == NULL) &&
(robject->type == OBJT_DEFAULT ||
robject->type == OBJT_SWAP)) {
int s;
robject->ref_count += 2;
object->ref_count += 2;
do {
s = splhigh();
while (robject->paging_in_progress) {
robject->flags |= OBJ_PIPWNT;
tsleep(robject, PVM, "objde1", 0);
}
while (object->paging_in_progress) {
object->flags |= OBJ_PIPWNT;
tsleep(object, PVM, "objde2", 0);
}
splx(s);
} while( object->paging_in_progress || robject->paging_in_progress);
object->ref_count -= 2;
robject->ref_count -= 2;
if( robject->ref_count == 0) {
robject->ref_count += 1;
object = robject;
continue;
}
vm_object_collapse(robject);
return;
}
}
/*
* If there are still references, then we are done.
*/
return;
}
if (object->type == OBJT_VNODE) {
struct vnode *vp = object->handle;
vp->v_flag &= ~VTEXT;
}
/*
* See if this object can persist and has some resident
* pages. If so, enter it in the cache.
*/
if (object->flags & OBJ_CANPERSIST) {
if (object->resident_page_count != 0) {
vm_object_page_clean(object, 0, 0 ,TRUE, TRUE);
TAILQ_INSERT_TAIL(&vm_object_cached_list, object,
cached_list);
vm_object_cached++;
vm_object_cache_trim();
return;
} else {
object->flags &= ~OBJ_CANPERSIST;
}
}
/*
* Make sure no one uses us.
*/
object->flags |= OBJ_DEAD;
temp = object->backing_object;
if (temp) {
TAILQ_REMOVE(&temp->shadow_head, object, shadow_list);
--temp->shadow_count;
}
vm_object_terminate(object);
/* unlocks and deallocates object */
object = temp;
}
}
/*
* vm_object_terminate actually destroys the specified object, freeing
* up all previously used resources.
*
* The object must be locked.
*/
static void
vm_object_terminate(object)
register vm_object_t object;
{
register vm_page_t p;
int s;
/*
* wait for the pageout daemon to be done with the object
*/
s = splhigh();
while (object->paging_in_progress) {
object->flags |= OBJ_PIPWNT;
tsleep(object, PVM, "objtrm", 0);
}
splx(s);
if (object->paging_in_progress != 0)
panic("vm_object_deallocate: pageout in progress");
/*
* Clean and free the pages, as appropriate. All references to the
* object are gone, so we don't need to lock it.
*/
if (object->type == OBJT_VNODE) {
struct vnode *vp = object->handle;
VOP_LOCK(vp);
vm_object_page_clean(object, 0, 0, TRUE, FALSE);
vinvalbuf(vp, V_SAVE, NOCRED, NULL, 0, 0);
VOP_UNLOCK(vp);
}
/*
* Now free the pages. For internal objects, this also removes them
* from paging queues.
*/
while ((p = object->memq.tqh_first) != NULL) {
if (p->flags & PG_BUSY)
printf("vm_object_terminate: freeing busy page\n");
PAGE_WAKEUP(p);
vm_page_free(p);
cnt.v_pfree++;
}
/*
* Let the pager know object is dead.
*/
vm_pager_deallocate(object);
TAILQ_REMOVE(&vm_object_list, object, object_list);
vm_object_count--;
wakeup(object);
/*
* Free the space for the object.
*/
free((caddr_t) object, M_VMOBJ);
}
/*
* vm_object_page_clean
*
* Clean all dirty pages in the specified range of object.
* Leaves page on whatever queue it is currently on.
*
* Odd semantics: if start == end, we clean everything.
*
* The object must be locked.
*/
void
vm_object_page_clean(object, start, end, syncio, lockflag)
vm_object_t object;
vm_pindex_t start;
vm_pindex_t end;
boolean_t syncio;
boolean_t lockflag;
{
register vm_page_t p, np, tp;
register vm_offset_t tstart, tend;
vm_pindex_t pi;
int s;
struct vnode *vp;
int runlen;
int maxf;
int chkb;
int maxb;
int i;
vm_page_t maf[vm_pageout_page_count];
vm_page_t mab[vm_pageout_page_count];
vm_page_t ma[vm_pageout_page_count];
if (object->type != OBJT_VNODE ||
(object->flags & OBJ_MIGHTBEDIRTY) == 0)
return;
vp = object->handle;
if (lockflag)
VOP_LOCK(vp);
object->flags |= OBJ_CLEANING;
tstart = start;
if (end == 0) {
tend = object->size;
} else {
tend = end;
}
if ((tstart == 0) && (tend == object->size)) {
object->flags &= ~(OBJ_WRITEABLE|OBJ_MIGHTBEDIRTY);
}
for(p = object->memq.tqh_first; p; p = p->listq.tqe_next)
p->flags |= PG_CLEANCHK;
rescan:
for(p = object->memq.tqh_first; p; p = np) {
np = p->listq.tqe_next;
pi = p->pindex;
if (((p->flags & PG_CLEANCHK) == 0) ||
(pi < tstart) || (pi >= tend) ||
(p->valid == 0) || (p->queue == PQ_CACHE)) {
p->flags &= ~PG_CLEANCHK;
continue;
}
vm_page_test_dirty(p);
if ((p->dirty & p->valid) == 0) {
p->flags &= ~PG_CLEANCHK;
continue;
}
s = splhigh();
if ((p->flags & PG_BUSY) || p->busy) {
p->flags |= PG_WANTED|PG_REFERENCED;
tsleep(p, PVM, "vpcwai", 0);
splx(s);
goto rescan;
}
splx(s);
maxf = 0;
for(i=1;i<vm_pageout_page_count;i++) {
if (tp = vm_page_lookup(object, pi + i)) {
if ((tp->flags & PG_BUSY) ||
(tp->flags & PG_CLEANCHK) == 0)
break;
vm_page_test_dirty(tp);
if ((tp->dirty & tp->valid) == 0) {
tp->flags &= ~PG_CLEANCHK;
break;
}
maf[ i - 1 ] = tp;
maxf++;
continue;
}
break;
}
maxb = 0;
chkb = vm_pageout_page_count - maxf;
if (chkb) {
for(i = 1; i < chkb;i++) {
if (tp = vm_page_lookup(object, pi - i)) {
if ((tp->flags & PG_BUSY) ||
(tp->flags & PG_CLEANCHK) == 0)
break;
vm_page_test_dirty(tp);
if ((tp->dirty & tp->valid) == 0) {
tp->flags &= ~PG_CLEANCHK;
break;
}
mab[ i - 1 ] = tp;
maxb++;
continue;
}
break;
}
}
for(i=0;i<maxb;i++) {
int index = (maxb - i) - 1;
ma[index] = mab[i];
ma[index]->flags |= PG_BUSY;
ma[index]->flags &= ~PG_CLEANCHK;
vm_page_protect(ma[index], VM_PROT_READ);
}
vm_page_protect(p, VM_PROT_READ);
p->flags |= PG_BUSY;
p->flags &= ~PG_CLEANCHK;
ma[maxb] = p;
for(i=0;i<maxf;i++) {
int index = (maxb + i) + 1;
ma[index] = maf[i];
ma[index]->flags |= PG_BUSY;
ma[index]->flags &= ~PG_CLEANCHK;
vm_page_protect(ma[index], VM_PROT_READ);
}
runlen = maxb + maxf + 1;
/*
printf("maxb: %d, maxf: %d, runlen: %d, offset: %d\n", maxb, maxf, runlen, ma[0]->pindex);
*/
vm_pageout_flush(ma, runlen, 0);
goto rescan;
}
VOP_FSYNC(vp, NULL, syncio, curproc);
if (lockflag)
VOP_UNLOCK(vp);
object->flags &= ~OBJ_CLEANING;
return;
}
#ifdef not_used
/* XXX I cannot tell if this should be an exported symbol */
/*
* vm_object_deactivate_pages
*
* Deactivate all pages in the specified object. (Keep its pages
* in memory even though it is no longer referenced.)
*
* The object must be locked.
*/
static void
vm_object_deactivate_pages(object)
register vm_object_t object;
{
register vm_page_t p, next;
for (p = object->memq.tqh_first; p != NULL; p = next) {
next = p->listq.tqe_next;
vm_page_deactivate(p);
}
}
#endif
/*
* Trim the object cache to size.
*/
static void
vm_object_cache_trim()
{
register vm_object_t object;
while (vm_object_cached > vm_object_cache_max) {
object = vm_object_cached_list.tqh_first;
vm_object_reference(object);
pager_cache(object, FALSE);
}
}
/*
* vm_object_pmap_copy:
*
* Makes all physical pages in the specified
* object range copy-on-write. No writeable
* references to these pages should remain.
*
* The object must *not* be locked.
*/
void
vm_object_pmap_copy(object, start, end)
register vm_object_t object;
register vm_pindex_t start;
register vm_pindex_t end;
{
register vm_page_t p;
if (object == NULL || (object->flags & OBJ_WRITEABLE) == 0)
return;
for (p = object->memq.tqh_first; p != NULL; p = p->listq.tqe_next) {
vm_page_protect(p, VM_PROT_READ);
}
object->flags &= ~OBJ_WRITEABLE;
}
/*
* vm_object_pmap_remove:
*
* Removes all physical pages in the specified
* object range from all physical maps.
*
* The object must *not* be locked.
*/
void
vm_object_pmap_remove(object, start, end)
register vm_object_t object;
register vm_pindex_t start;
register vm_pindex_t end;
{
register vm_page_t p;
if (object == NULL)
return;
for (p = object->memq.tqh_first; p != NULL; p = p->listq.tqe_next) {
if (p->pindex >= start && p->pindex < end)
vm_page_protect(p, VM_PROT_NONE);
}
}
/*
* vm_object_copy:
*
* Create a new object which is a copy of an existing
* object, and mark all of the pages in the existing
* object 'copy-on-write'. The new object has one reference.
* Returns the new object.
*
* May defer the copy until later if the object is not backed
* up by a non-default pager.
*
*/
void
vm_object_copy(src_object, src_offset,
dst_object, dst_offset, src_needs_copy)
register vm_object_t src_object;
vm_pindex_t src_offset;
vm_object_t *dst_object;/* OUT */
vm_pindex_t *dst_offset;/* OUT */
boolean_t *src_needs_copy; /* OUT */
{
if (src_object == NULL) {
/*
* Nothing to copy
*/
*dst_object = NULL;
*dst_offset = 0;
*src_needs_copy = FALSE;
return;
}
/*
* Try to collapse the object before copying it.
*/
if (src_object->handle == NULL &&
(src_object->type == OBJT_DEFAULT ||
src_object->type == OBJT_SWAP))
vm_object_collapse(src_object);
/*
* Make another reference to the object
*/
src_object->ref_count++;
*dst_object = src_object;
*dst_offset = src_offset;
/*
* Must make a shadow when write is desired
*/
*src_needs_copy = TRUE;
return;
}
/*
* vm_object_shadow:
*
* Create a new object which is backed by the
* specified existing object range. The source
* object reference is deallocated.
*
* The new object and offset into that object
* are returned in the source parameters.
*/
void
vm_object_shadow(object, offset, length)
vm_object_t *object; /* IN/OUT */
vm_ooffset_t *offset; /* IN/OUT */
vm_size_t length;
{
register vm_object_t source;
register vm_object_t result;
source = *object;
/*
* Allocate a new object with the given length
*/
if ((result = vm_object_allocate(OBJT_DEFAULT, length)) == NULL)
panic("vm_object_shadow: no object for shadowing");
/*
* The new object shadows the source object, adding a reference to it.
* Our caller changes his reference to point to the new object,
* removing a reference to the source object. Net result: no change
* of reference count.
*/
result->backing_object = source;
if (source) {
TAILQ_INSERT_TAIL(&source->shadow_head, result, shadow_list);
++source->shadow_count;
}
/*
* Store the offset into the source object, and fix up the offset into
* the new object.
*/
result->backing_object_offset = *offset;
/*
* Return the new things
*/
*offset = 0;
*object = result;
}
/*
* this version of collapse allows the operation to occur earlier and
* when paging_in_progress is true for an object... This is not a complete
* operation, but should plug 99.9% of the rest of the leaks.
*/
static void
vm_object_qcollapse(object)
register vm_object_t object;
{
register vm_object_t backing_object;
register vm_pindex_t backing_offset_index, paging_offset_index;
vm_pindex_t backing_object_paging_offset_index;
vm_pindex_t new_pindex;
register vm_page_t p, pp;
register vm_size_t size;
backing_object = object->backing_object;
if (backing_object->ref_count != 1)
return;
backing_object->ref_count += 2;
backing_offset_index = OFF_TO_IDX(object->backing_object_offset);
backing_object_paging_offset_index = OFF_TO_IDX(backing_object->paging_offset);
paging_offset_index = OFF_TO_IDX(object->paging_offset);
size = object->size;
p = backing_object->memq.tqh_first;
while (p) {
vm_page_t next;
next = p->listq.tqe_next;
if ((p->flags & (PG_BUSY | PG_FICTITIOUS)) ||
(p->queue == PQ_CACHE) || !p->valid || p->hold_count || p->wire_count || p->busy) {
p = next;
continue;
}
vm_page_protect(p, VM_PROT_NONE);
new_pindex = p->pindex - backing_offset_index;
if (p->pindex < backing_offset_index ||
new_pindex >= size) {
if (backing_object->type == OBJT_SWAP)
swap_pager_freespace(backing_object,
backing_object_paging_offset_index+p->pindex,
1);
vm_page_free(p);
} else {
pp = vm_page_lookup(object, new_pindex);
if (pp != NULL || (object->type == OBJT_SWAP && vm_pager_has_page(object,
paging_offset_index + new_pindex, NULL, NULL))) {
if (backing_object->type == OBJT_SWAP)
swap_pager_freespace(backing_object,
backing_object_paging_offset_index + p->pindex, 1);
vm_page_free(p);
} else {
if (backing_object->type == OBJT_SWAP)
swap_pager_freespace(backing_object,
backing_object_paging_offset_index + p->pindex, 1);
vm_page_rename(p, object, new_pindex);
p->dirty = VM_PAGE_BITS_ALL;
}
}
p = next;
}
backing_object->ref_count -= 2;
}
/*
* vm_object_collapse:
*
* Collapse an object with the object backing it.
* Pages in the backing object are moved into the
* parent, and the backing object is deallocated.
*/
void
vm_object_collapse(object)
vm_object_t object;
{
vm_object_t backing_object;
vm_ooffset_t backing_offset;
vm_size_t size;
vm_pindex_t new_pindex, backing_offset_index;
vm_page_t p, pp;
while (TRUE) {
/*
* Verify that the conditions are right for collapse:
*
* The object exists and no pages in it are currently being paged
* out.
*/
if (object == NULL)
return;
/*
* Make sure there is a backing object.
*/
if ((backing_object = object->backing_object) == NULL)
return;
/*
* we check the backing object first, because it is most likely
* not collapsable.
*/
if (backing_object->handle != NULL ||
(backing_object->type != OBJT_DEFAULT &&
backing_object->type != OBJT_SWAP) ||
(backing_object->flags & OBJ_DEAD) ||
object->handle != NULL ||
(object->type != OBJT_DEFAULT &&
object->type != OBJT_SWAP) ||
(object->flags & OBJ_DEAD)) {
return;
}
if (object->paging_in_progress != 0 ||
backing_object->paging_in_progress != 0) {
vm_object_qcollapse(object);
return;
}
/*
* We know that we can either collapse the backing object (if
* the parent is the only reference to it) or (perhaps) remove
* the parent's reference to it.
*/
backing_offset = object->backing_object_offset;
backing_offset_index = OFF_TO_IDX(backing_offset);
size = object->size;
/*
* If there is exactly one reference to the backing object, we
* can collapse it into the parent.
*/
if (backing_object->ref_count == 1) {
backing_object->flags |= OBJ_DEAD;
/*
* We can collapse the backing object.
*
* Move all in-memory pages from backing_object to the
* parent. Pages that have been paged out will be
* overwritten by any of the parent's pages that
* shadow them.
*/
while ((p = backing_object->memq.tqh_first) != 0) {
new_pindex = p->pindex - backing_offset_index;
/*
* If the parent has a page here, or if this
* page falls outside the parent, dispose of
* it.
*
* Otherwise, move it as planned.
*/
if (p->pindex < backing_offset_index ||
new_pindex >= size) {
vm_page_protect(p, VM_PROT_NONE);
PAGE_WAKEUP(p);
vm_page_free(p);
} else {
pp = vm_page_lookup(object, new_pindex);
if (pp != NULL || (object->type == OBJT_SWAP && vm_pager_has_page(object,
OFF_TO_IDX(object->paging_offset) + new_pindex, NULL, NULL))) {
vm_page_protect(p, VM_PROT_NONE);
PAGE_WAKEUP(p);
vm_page_free(p);
} else {
vm_page_rename(p, object, new_pindex);
}
}
}
/*
* Move the pager from backing_object to object.
*/
if (backing_object->type == OBJT_SWAP) {
backing_object->paging_in_progress++;
if (object->type == OBJT_SWAP) {
object->paging_in_progress++;
/*
* copy shadow object pages into ours
* and destroy unneeded pages in
* shadow object.
*/
swap_pager_copy(
backing_object,
OFF_TO_IDX(backing_object->paging_offset),
object,
OFF_TO_IDX(object->paging_offset),
OFF_TO_IDX(object->backing_object_offset));
vm_object_pip_wakeup(object);
} else {
object->paging_in_progress++;
/*
* move the shadow backing_object's pager data to
* "object" and convert "object" type to OBJT_SWAP.
*/
object->type = OBJT_SWAP;
object->un_pager.swp.swp_nblocks =
backing_object->un_pager.swp.swp_nblocks;
object->un_pager.swp.swp_allocsize =
backing_object->un_pager.swp.swp_allocsize;
object->un_pager.swp.swp_blocks =
backing_object->un_pager.swp.swp_blocks;
object->un_pager.swp.swp_poip = /* XXX */
backing_object->un_pager.swp.swp_poip;
object->paging_offset = backing_object->paging_offset + backing_offset;
TAILQ_INSERT_TAIL(&swap_pager_un_object_list, object, pager_object_list);
/*
* Convert backing object from OBJT_SWAP to
* OBJT_DEFAULT. XXX - only the TAILQ_REMOVE is
* actually necessary.
*/
backing_object->type = OBJT_DEFAULT;
TAILQ_REMOVE(&swap_pager_un_object_list, backing_object, pager_object_list);
/*
* free unnecessary blocks
*/
swap_pager_freespace(object, 0,
OFF_TO_IDX(object->paging_offset));
vm_object_pip_wakeup(object);
}
vm_object_pip_wakeup(backing_object);
}
/*
* Object now shadows whatever backing_object did.
* Note that the reference to backing_object->backing_object
* moves from within backing_object to within object.
*/
TAILQ_REMOVE(&object->backing_object->shadow_head, object,
shadow_list);
--object->backing_object->shadow_count;
if (backing_object->backing_object) {
TAILQ_REMOVE(&backing_object->backing_object->shadow_head,
backing_object, shadow_list);
--backing_object->backing_object->shadow_count;
}
object->backing_object = backing_object->backing_object;
if (object->backing_object) {
TAILQ_INSERT_TAIL(&object->backing_object->shadow_head,
object, shadow_list);
++object->backing_object->shadow_count;
}
object->backing_object_offset += backing_object->backing_object_offset;
/*
* Discard backing_object.
*
* Since the backing object has no pages, no pager left,
* and no object references within it, all that is
* necessary is to dispose of it.
*/
TAILQ_REMOVE(&vm_object_list, backing_object,
object_list);
vm_object_count--;
free((caddr_t) backing_object, M_VMOBJ);
object_collapses++;
} else {
/*
* If all of the pages in the backing object are
* shadowed by the parent object, the parent object no
* longer has to shadow the backing object; it can
* shadow the next one in the chain.
*
* The backing object must not be paged out - we'd have
* to check all of the paged-out pages, as well.
*/
if (backing_object->type != OBJT_DEFAULT) {
return;
}
/*
* Should have a check for a 'small' number of pages
* here.
*/
for (p = backing_object->memq.tqh_first; p; p = p->listq.tqe_next) {
new_pindex = p->pindex - backing_offset_index;
/*
* If the parent has a page here, or if this
* page falls outside the parent, keep going.
*
* Otherwise, the backing_object must be left in
* the chain.
*/
if (p->pindex >= backing_offset_index &&
new_pindex <= size) {
pp = vm_page_lookup(object, new_pindex);
if ((pp == NULL || pp->valid == 0) &&
!vm_pager_has_page(object, OFF_TO_IDX(object->paging_offset) + new_pindex, NULL, NULL)) {
/*
* Page still needed. Can't go any
* further.
*/
return;
}
}
}
/*
* Make the parent shadow the next object in the
* chain. Deallocating backing_object will not remove
* it, since its reference count is at least 2.
*/
TAILQ_REMOVE(&object->backing_object->shadow_head,
object, shadow_list);
--object->backing_object->shadow_count;
vm_object_reference(object->backing_object = backing_object->backing_object);
if (object->backing_object) {
TAILQ_INSERT_TAIL(&object->backing_object->shadow_head,
object, shadow_list);
++object->backing_object->shadow_count;
}
object->backing_object_offset += backing_object->backing_object_offset;
/*
* Drop the reference count on backing_object. Since
* its ref_count was at least 2, it will not vanish;
* so we don't need to call vm_object_deallocate.
*/
if (backing_object->ref_count == 1)
printf("should have called obj deallocate\n");
backing_object->ref_count--;
object_bypasses++;
}
/*
* Try again with this object's new backing object.
*/
}
}
/*
* vm_object_page_remove: [internal]
*
* Removes all physical pages in the specified
* object range from the object's list of pages.
*
* The object must be locked.
*/
void
vm_object_page_remove(object, start, end, clean_only)
register vm_object_t object;
register vm_pindex_t start;
register vm_pindex_t end;
boolean_t clean_only;
{
register vm_page_t p, next;
unsigned int size;
int s;
if (object == NULL)
return;
object->paging_in_progress++;
again:
size = end - start;
if (size > 4 || size >= object->size / 4) {
for (p = object->memq.tqh_first; p != NULL; p = next) {
next = p->listq.tqe_next;
if (p->wire_count != 0) {
vm_page_protect(p, VM_PROT_NONE);
p->valid = 0;
continue;
}
if ((start <= p->pindex) && (p->pindex < end)) {
s = splhigh();
if ((p->flags & PG_BUSY) || p->busy) {
p->flags |= PG_WANTED;
tsleep(p, PVM, "vmopar", 0);
splx(s);
goto again;
}
splx(s);
if (clean_only) {
vm_page_test_dirty(p);
if (p->valid & p->dirty)
continue;
}
vm_page_protect(p, VM_PROT_NONE);
PAGE_WAKEUP(p);
vm_page_free(p);
}
}
} else {
while (size > 0) {
if ((p = vm_page_lookup(object, start)) != 0) {
if (p->wire_count != 0) {
p->valid = 0;
vm_page_protect(p, VM_PROT_NONE);
start += 1;
size -= 1;
continue;
}
s = splhigh();
if ((p->flags & PG_BUSY) || p->busy) {
p->flags |= PG_WANTED;
tsleep(p, PVM, "vmopar", 0);
splx(s);
goto again;
}
splx(s);
if (clean_only) {
vm_page_test_dirty(p);
if (p->valid & p->dirty) {
start += 1;
size -= 1;
continue;
}
}
vm_page_protect(p, VM_PROT_NONE);
PAGE_WAKEUP(p);
vm_page_free(p);
}
start += 1;
size -= 1;
}
}
vm_object_pip_wakeup(object);
}
/*
* Routine: vm_object_coalesce
* Function: Coalesces two objects backing up adjoining
* regions of memory into a single object.
*
* returns TRUE if objects were combined.
*
* NOTE: Only works at the moment if the second object is NULL -
* if it's not, which object do we lock first?
*
* Parameters:
* prev_object First object to coalesce
* prev_offset Offset into prev_object
* next_object Second object into coalesce
* next_offset Offset into next_object
*
* prev_size Size of reference to prev_object
* next_size Size of reference to next_object
*
* Conditions:
* The object must *not* be locked.
*/
boolean_t
vm_object_coalesce(prev_object, prev_pindex, prev_size, next_size)
register vm_object_t prev_object;
vm_pindex_t prev_pindex;
vm_size_t prev_size, next_size;
{
vm_size_t newsize;
if (prev_object == NULL) {
return (TRUE);
}
if (prev_object->type != OBJT_DEFAULT) {
return (FALSE);
}
/*
* Try to collapse the object first
*/
vm_object_collapse(prev_object);
/*
* Can't coalesce if: . more than one reference . paged out . shadows
* another object . has a copy elsewhere (any of which mean that the
* pages not mapped to prev_entry may be in use anyway)
*/
if (prev_object->ref_count > 1 ||
prev_object->backing_object != NULL) {
return (FALSE);
}
prev_size >>= PAGE_SHIFT;
next_size >>= PAGE_SHIFT;
/*
* Remove any pages that may still be in the object from a previous
* deallocation.
*/
vm_object_page_remove(prev_object,
prev_pindex + prev_size,
prev_pindex + prev_size + next_size, FALSE);
/*
* Extend the object if necessary.
*/
newsize = prev_pindex + prev_size + next_size;
if (newsize > prev_object->size)
prev_object->size = newsize;
return (TRUE);
}
#ifdef DDB
static int
_vm_object_in_map(map, object, entry)
vm_map_t map;
vm_object_t object;
vm_map_entry_t entry;
{
vm_map_t tmpm;
vm_map_entry_t tmpe;
vm_object_t obj;
int entcount;
if (map == 0)
return 0;
if (entry == 0) {
tmpe = map->header.next;
entcount = map->nentries;
while (entcount-- && (tmpe != &map->header)) {
if( _vm_object_in_map(map, object, tmpe)) {
return 1;
}
tmpe = tmpe->next;
}
} else if (entry->is_sub_map || entry->is_a_map) {
tmpm = entry->object.share_map;
tmpe = tmpm->header.next;
entcount = tmpm->nentries;
while (entcount-- && tmpe != &tmpm->header) {
if( _vm_object_in_map(tmpm, object, tmpe)) {
return 1;
}
tmpe = tmpe->next;
}
} else if (obj = entry->object.vm_object) {
for(; obj; obj=obj->backing_object)
if( obj == object) {
return 1;
}
}
return 0;
}
static int
vm_object_in_map( object)
vm_object_t object;
{
struct proc *p;
for (p = allproc.lh_first; p != 0; p = p->p_list.le_next) {
if( !p->p_vmspace /* || (p->p_flag & (P_SYSTEM|P_WEXIT)) */)
continue;
/*
if (p->p_stat != SRUN && p->p_stat != SSLEEP) {
continue;
}
*/
if( _vm_object_in_map(&p->p_vmspace->vm_map, object, 0))
return 1;
}
if( _vm_object_in_map( kernel_map, object, 0))
return 1;
if( _vm_object_in_map( kmem_map, object, 0))
return 1;
if( _vm_object_in_map( pager_map, object, 0))
return 1;
if( _vm_object_in_map( buffer_map, object, 0))
return 1;
if( _vm_object_in_map( io_map, object, 0))
return 1;
if( _vm_object_in_map( phys_map, object, 0))
return 1;
if( _vm_object_in_map( mb_map, object, 0))
return 1;
if( _vm_object_in_map( u_map, object, 0))
return 1;
return 0;
}
#ifdef DDB
static void
DDB_vm_object_check()
{
vm_object_t object;
/*
* make sure that internal objs are in a map somewhere
* and none have zero ref counts.
*/
for (object = vm_object_list.tqh_first;
object != NULL;
object = object->object_list.tqe_next) {
if (object->handle == NULL &&
(object->type == OBJT_DEFAULT || object->type == OBJT_SWAP)) {
if (object->ref_count == 0) {
printf("vmochk: internal obj has zero ref count: %d\n",
object->size);
}
if (!vm_object_in_map(object)) {
printf("vmochk: internal obj is not in a map: "
"ref: %d, size: %d: 0x%x, backing_object: 0x%x\n",
object->ref_count, object->size,
object->size, object->backing_object);
}
}
}
}
#endif /* DDB */
/*
* vm_object_print: [ debug ]
*/
void
vm_object_print(iobject, full, dummy3, dummy4)
/* db_expr_t */ int iobject;
boolean_t full;
/* db_expr_t */ int dummy3;
char *dummy4;
{
vm_object_t object = (vm_object_t)iobject; /* XXX */
register vm_page_t p;
register int count;
if (object == NULL)
return;
iprintf("Object 0x%x: size=0x%x, res=%d, ref=%d, ",
(int) object, (int) object->size,
object->resident_page_count, object->ref_count);
printf("offset=0x%x, backing_object=(0x%x)+0x%x\n",
(int) object->paging_offset,
(int) object->backing_object, (int) object->backing_object_offset);
printf("cache: next=%p, prev=%p\n",
object->cached_list.tqe_next, object->cached_list.tqe_prev);
if (!full)
return;
indent += 2;
count = 0;
for (p = object->memq.tqh_first; p != NULL; p = p->listq.tqe_next) {
if (count == 0)
iprintf("memory:=");
else if (count == 6) {
printf("\n");
iprintf(" ...");
count = 0;
} else
printf(",");
count++;
printf("(off=0x%lx,page=0x%lx)",
(u_long) p->pindex, (u_long) VM_PAGE_TO_PHYS(p));
}
if (count != 0)
printf("\n");
indent -= 2;
}
#endif /* DDB */
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