Author: alc
Date: Thu Jun 26 16:04:03 2014
New Revision: 267917
URL: http://svnweb.freebsd.org/changeset/base/267917
Log:
Delay the call to crhold() in vm_map_insert() until we know that we won't
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
Modified:
head/sys/vm/vm_map.c
Modified: head/sys/vm/vm_map.c
==============================================================================
--- head/sys/vm/vm_map.c Thu Jun 26 15:25:42 2014 (r267916)
+++ head/sys/vm/vm_map.c Thu Jun 26 16:04:03 2014 (r267917)
@@ -1127,7 +1127,6 @@ vm_map_insert(vm_map_t map, vm_object_t
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
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->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
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