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Method for Spin Loop Detection Disclosure Number: IPCOM000037247D
Original Publication Date: 1989-Dec-01
Included in the Prior Art Database: 2005-Jan-29

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Bowen, NS Knight, JW [+details]


Multiprocessing/processor systems that share memory locations provide atomic memory update instructions. An example is the Compare and Swap (CS) instruction on the IBM System/370. This instruction allows one to atomically Compare a memory word against a register and, if successful, to Swap another register into the memory location. The use of these instructions often have an execution path that retries the instructions until the compare succeeds. This retry path is often referred to as a spin loop. These loops can cause the processor to wait (while executing instructions) for some set of conditions to be met. This can degrade the overall performance of the system. (Image Omitted). There are two primary areas for which the CS is used: 1. Process Serialization.