Further improvements

At the beginning of Read-modify-write, we described how a global total order is established by combining local order and inter-thread order imposed by atomic objects. But should every object, including non-atomic ones, participate in a single global order established by atomic objects? Sequential consistency solves the ordering problem in Enforcing law and order, but it may force too much ordering, as some normal operations may not require it. By default, atomic operations in the C11 atomic library use memory_order_seq_cst as the default memory order. Operations with the _explicit suffix accept an additional argument to specify which memory order to use. How to leverage memory orders to optimize performance will be covered later in Do we always need sequentially consistent operations?.