The `InstanceKlass::find_method_by_name` and `InstanceKlass::find_method_index` use `InstanceKlass::quick_search` to find a method by name.  If the method found doesn't match the expected method signature, It has to search downwards and upwards. But if `_disable_method_binary_search` was set to `true`, the `InstanceKlass::quick_search` will use linear search instead of binary search to find the method. So there no needs to search downwards because there no other method with the same name before it since the method found is the first match method.