HiperDispatch

Article summary

HiperDispatch is a workload dispatching feature found in recent IBM mainframe models (the System z10 and IBM zEnterprise System processors and later models) running recent releases of z/OS. HiperDispatch was introduced in February 2008. Support was added to z/VM in its V6R3 release on July 26, 2013. One of the engineering challenges with large SMP server designs is to maintain near-linear scalability as the number of CPUs increases. Performance and throughput do not double when doubling the number of processors. There are many overhead factors, including contention for cache and main memory access. These overhead factors become increasingly difficult to mitigate as the number of CPUs increases. The design goal for delivering maximum performance is to minimize those overhead factors. Each new mainframe model supports a higher maximum number of CPUs (up to 64 main processors in a single System z10 mainframe for example), so this engineering challenge becomes ever more important. HiperDispatch helps address the problem through a combination of hardware features, z/OS dispatching, and the z/OS Workload Manager. In z/OS there may be tasks waiting for processing attention, such as transaction programs. Each task requires frequent access to memory.…

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