* Avoid calling vm_unreserve_memory() if there is no change in the commited

size. Removes a bit of overhead (call and mutex_lock / mutex_unlock).
* Don't fail if there is exactly enough memory available to satisfy the
  reserve request. Not that it would really matter as it's rather an edge case...

git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@26246 a95241bf-73f2-0310-859d-f6bbb57e9c96

src/system/kernel/vm/vm.cpp

@@ -4761,7 +4761,7 @@ vm_try_reserve_memory(size_t amount)
 
 	//dprintf("try to reserve %lu bytes, %Lu left\n", amount, sAvailableMemory);
 
-	if (sAvailableMemory > amount) {
+	if (sAvailableMemory >= amount) {
 		sAvailableMemory -= amount;
 		status = B_OK;
 	} else

src/system/kernel/vm/vm_store_anonymous_noswap.cpp

@@ -66,6 +66,9 @@ anonymous_commit(struct vm_store *_store, off_t size)
 			size = precommitted;
 	}
 
+	if (size == store->vm.committed_size)
+		return B_OK;
+
 	// Check to see how much we could commit - we need real memory
 
 	if (size > store->vm.committed_size) {