SMT: Deciding Whether to Enable
Project and Program: MVS
, MVS Performance
, SHARE San Jose 2017
Should you enable Simultaneous Multithreading (SMT) on your z13 or z13s for your zIIP workloads? That is an interesting question that doesn’t have an easy answer. If you do enable SMT you should be prepared to review a number of SMT-specific measurements as well as your standard application measurements. Since there is some potential work in terms of evaluating the impact of the change, you may want to first consider whether it seems like it may be beneficial. While it is impossible to predict the actual impact SMT will have on a given system, there are situations which don’t lend themselves to SMT.
Join Scott Chapman for this session where he’ll explain some of the measurements that may be leading indicators for whether or not SMT should be explored. Existing pertinent SMF/RMF measurements will be reviewed, the SMT measurements will be briefly introduced, and a decision tree for deciding whether to stay in single-threaded mode or try SMT-2 will be introduced.-Scott Chapman-Enterprise Performance Strategies Inc.
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