Synchronization inside InnoDB frequently involves the use of
spin loops: while waiting, InnoDB
executes a tight loop of instructions repeatedly to avoid having
the InnoDB process and
threads be rescheduled by the
operating system. If the spin loops are executed too quickly,
system resources are wasted, imposing a performance penalty on
transaction throughput. Most modern processors implement the
PAUSE instruction for use in spin loops, so the
processor can be more efficient.
InnoDB uses a
PAUSE instruction in its spin
loops on all platforms where such an instruction is available.
This technique increases overall performance with CPU-bound
workloads, and has the added benefit of minimizing power
consumption during the execution of the spin loops.
You do not have to do anything to take advantage of this performance improvement.
For performance considerations for InnoDB locking operations, see Optimizing Locking Operations.