A memory nest in a fully populated z14 ZR1 CPC drawer is shown in Figure 12-2. Workload performance is sensitive to how deep into the memory hierarchy the processor  must go to retrieve the workload instructions and data for running. The best performance  occurs when the instructions and data are in the caches nearest the processor because little  time is spent waiting before running. If the instructions and data must be retrieved from farther  out in the hierarchy, the processor spends more time waiting for their arrival. As workloads are moved between processors with various memory hierarchy designs,  performance varies because the average time to retrieve instructions and data from within the  memory hierarchy varies. Also, when on a processor, this component continues to vary  because the location of a workload’s instructions  and data within the memory hierarchy is  affected by several factors that include, but are not limited to, the following factors: Figure 12-2 Memory hierarchy in a fully populated z14 ZR1 CPC drawer GLYPH<SM590000> Locality of reference GLYPH<SM590000> I/O rate GLYPH<SM590000> Competition from other applications and LPARs The most performance-sensitive area of the memory hierarchy is the activity to the memory  nest. This area is the distribution of activity to the shared caches and memory.  The term Relative Nest Intensity (RNI) indicates the level of activity to this part of the memory  hierarchy. By using data from CPU MF, the RNI of the workload that is running in an LPAR can  be calculated. The higher the RNI, the deeper into the memory hierarchy the processor must  go to retrieve the instructions and data for that workload. 12.4 Relative Nest Intensity Chapter 12. Performance  401