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Remove a bogus optimization in the mmap code. It is superfluous,

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and at best is the same speed as the unoptimized code.  At worst, it
slows down trivial programs.
This commit is contained in:
dyson 1996-10-24 02:56:23 +00:00
parent 1b9def83a5
commit 30a1549ad1
1 changed files with 5 additions and 24 deletions
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29
sys/vm/vm_mmap.c
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@ -38,7 +38,7 @@
* from: Utah $Hdr: vm_mmap.c 1.6 91/10/21$
*
* @(#)vm_mmap.c 8.4 (Berkeley) 1/12/94
* $Id: vm_mmap.c,v 1.50 1996/09/19 10:12:41 davidg Exp $
* $Id: vm_mmap.c,v 1.51 1996/10/13 07:16:50 phk Exp $
*/
/*
@ -843,7 +843,7 @@ vm_mmap(map, addr, size, prot, maxprot, flags, handle, foff)
vm_ooffset_t foff;
{
boolean_t fitit;
vm_object_t object, object2;
vm_object_t object;
struct vnode *vp = NULL;
objtype_t type;
int rv = KERN_SUCCESS;
@ -915,28 +915,12 @@ vm_mmap(map, addr, size, prot, maxprot, flags, handle, foff)
flags |= MAP_SHARED;
}
object2 = NULL;
docow = 0;
if ((flags & (MAP_ANON|MAP_SHARED)) == 0) {
docow = MAP_COPY_ON_WRITE;
if (objsize < size) {
object2 = vm_object_allocate( OBJT_DEFAULT,
OFF_TO_IDX(size - (foff & ~PAGE_MASK)));
object2->backing_object = object;
object2->backing_object_offset = foff;
TAILQ_INSERT_TAIL(&object->shadow_head,
object2, shadow_list);
++object->shadow_count;
} else {
docow |= MAP_COPY_NEEDED;
}
docow = MAP_COPY_ON_WRITE | MAP_COPY_NEEDED;
}
if (object2)
rv = vm_map_find(map, object2, 0, addr, size, fitit,
prot, maxprot, docow);
else
rv = vm_map_find(map, object, foff, addr, size, fitit,
rv = vm_map_find(map, object, foff, addr, size, fitit,
prot, maxprot, docow);
@ -946,10 +930,7 @@ vm_mmap(map, addr, size, prot, maxprot, flags, handle, foff)
* object if it's an unnamed anonymous mapping
* or named anonymous without other references.
*/
if (object2)
vm_object_deallocate(object2);
else
vm_object_deallocate(object);
vm_object_deallocate(object);
goto out;
}