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Delay the call to crhold() in vm_map_insert() until we know that we won't

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have to undo it by calling crfree().  This reduces the total number of calls
by vm_map_insert() to crhold() and crfree() by 45% in my tests.

Eliminate an unnecessary variable from vm_map_insert().

Reviewed by:	kib
Tested by:	pho
This commit is contained in:
alc 2014-06-26 16:04:03 +00:00
parent 3f3d544005
commit 50c074c333
1 changed files with 4 additions and 9 deletions
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13
sys/vm/vm_map.c
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@ -1127,7 +1127,6 @@ vm_map_insert(vm_map_t map, vm_object_t object, vm_ooffset_t offset,
vm_eflags_t protoeflags;
struct ucred *cred;
vm_inherit_t inheritance;
boolean_t charge_prev_obj;
VM_MAP_ASSERT_LOCKED(map);
KASSERT((object != kmem_object && object != kernel_object) ||
@ -1180,7 +1179,6 @@ vm_map_insert(vm_map_t map, vm_object_t object, vm_ooffset_t offset,
inheritance = VM_INHERIT_DEFAULT;
cred = NULL;
charge_prev_obj = FALSE;
if (cow & (MAP_ACC_NO_CHARGE | MAP_NOFAULT))
goto charged;
if ((cow & MAP_ACC_CHARGED) || ((prot & VM_PROT_WRITE) &&
@ -1191,9 +1189,6 @@ vm_map_insert(vm_map_t map, vm_object_t object, vm_ooffset_t offset,
object->cred == NULL,
("OVERCOMMIT: vm_map_insert o %p", object));
cred = curthread->td_ucred;
crhold(cred);
if (object == NULL && !(protoeflags & MAP_ENTRY_NEEDS_COPY))
charge_prev_obj = TRUE;
}
charged:
@ -1224,7 +1219,8 @@ charged:
vm_object_coalesce(prev_entry->object.vm_object,
prev_entry->offset,
(vm_size_t)(prev_entry->end - prev_entry->start),
(vm_size_t)(end - prev_entry->end), charge_prev_obj)) {
(vm_size_t)(end - prev_entry->end), cred != NULL &&
(protoeflags & MAP_ENTRY_NEEDS_COPY) == 0)) {
/*
* We were able to extend the object. Determine if we
* can extend the previous map entry to include the
@ -1237,8 +1233,6 @@ charged:
prev_entry->end = end;
vm_map_entry_resize_free(map, prev_entry);
vm_map_simplify_entry(map, prev_entry);
if (cred != NULL)
crfree(cred);
return (KERN_SUCCESS);
}
@ -1255,10 +1249,11 @@ charged:
if (cred != NULL && object != NULL && object->cred != NULL &&
!(prev_entry->eflags & MAP_ENTRY_NEEDS_COPY)) {
/* Object already accounts for this uid. */
crfree(cred);
cred = NULL;
}
}
if (cred != NULL)
crhold(cred);
/*
* Create a new entry