content_image/1005011.jpg
A memory nest in a fully populated z14 ZR1 CPC drawer is shown in Figure 12-2. 

<img src='content_image/1005011.jpg'>

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: 

## 12.4 Relative Nest Intensity 

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. 

