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InnoDB 1.1 for MySQL 5.5 User's Guide
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InnoDB 1.1 for MySQL 5.5 User's Guide  /  InnoDB Performance and Scalability Enhancements  /  Using the PAUSE Instruction in InnoDB Spin Loops

7.13. Using the PAUSE Instruction in InnoDB Spin Loops

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.

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