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Avoid the creation of unnecessary shadow objects.

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This commit is contained in:
Alan Cox 1999-05-28 03:39:44 +00:00
parent 323d972c29
commit 9a2f6362a7
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=47568
2 changed files with 20 additions and 4 deletions
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12
sys/vm/vm_map.c
View file

@ -61,7 +61,7 @@
* any improvements or extensions that they make and grant Carnegie the
* rights to redistribute these changes.
*
* $Id: vm_map.c,v 1.163 1999/05/17 00:53:53 alc Exp $
* $Id: vm_map.c,v 1.164 1999/05/18 05:38:48 alc Exp $
*/
/*
@ -2276,7 +2276,14 @@ vmspace_fork(vm1)
atop(old_entry->end - old_entry->start));
old_entry->object.vm_object = object;
old_entry->offset = (vm_offset_t) 0;
} else if (old_entry->eflags & MAP_ENTRY_NEEDS_COPY) {
}
/*
* Add the reference before calling vm_object_shadow
* to insure that a shadow object is created.
*/
vm_object_reference(object);
if (old_entry->eflags & MAP_ENTRY_NEEDS_COPY) {
vm_object_shadow(&old_entry->object.vm_object,
&old_entry->offset,
atop(old_entry->end - old_entry->start));
@ -2291,7 +2298,6 @@ vmspace_fork(vm1)
new_entry = vm_map_entry_create(new_map);
*new_entry = *old_entry;
new_entry->wired_count = 0;
vm_object_reference(object);
/*
* Insert the entry into the new map -- we know we're

12
sys/vm/vm_object.c
View file

@ -61,7 +61,7 @@
* any improvements or extensions that they make and grant Carnegie the
* rights to redistribute these changes.
*
* $Id: vm_object.c,v 1.153 1999/03/14 06:36:00 alc Exp $
* $Id: vm_object.c,v 1.154 1999/05/16 05:07:34 alc Exp $
*/
/*
@ -867,6 +867,16 @@ vm_object_shadow(object, offset, length)
source = *object;
/*
* Don't create the new object if the old object isn't shared.
*/
if (source->ref_count == 1 &&
source->handle == NULL &&
(source->type == OBJT_DEFAULT ||
source->type == OBJT_SWAP))
return;
/*
* Allocate a new object with the given length
*/