IBM Power7 Optimization And Tuning Manual page 104

Cache and memory affinity optimization
– Multi-threaded
Workloads must be multi-threaded to be considered for optimization.
– Workload Manager
Workloads that are classified by the Workload Manager (WLM) with tiers or minimum
limits set are not optimized. Furthermore, if the system CPU capacity is fully used,
ASO does not optimize processes that belong to classes with specific shares.
– User-specified placement
Workloads for which placement is explicitly set by the user, such as with bindprocessor,
RSET attachments (real, partition, or exclusive RSETs), and SRAD attachments, are
not eligible for ASO optimization. A though ASO does not affect these workloads, AIX
continues to enforce the resource constraints as normal. Furthermore, if the user
attempts to place such a restriction on a workload that has been or is being optimized
by ASO, then ASO undoes its optimization and lets the user restriction be placed
normally.
– CPU usage
The CPU usage of the workload should be above 0.1 cores.
– Workload age
Workloads must be at least 10 seconds of age to be considered for cache affinity and
5 minutes of age for memory affinity optimization.
Large page optimization
– Fully populated segments
The shared memory segments should be fully populated to be considered for page
size promotion.
– Memory footprint
The workload memory footprint should have at least 16 GB of System V
shared memory.
– CPU usage
CPU usage of the workload should be above two cores. A workload may be either a
multi-threaded process or a collection of single-threaded processes.
– Workload age
Workloads must be at least 60 minutes of age to be considered.
Memory prefetch optimization
– Memory footprint
The workload memory footprint should have at least 16 GB of System V
shared memory.
– CPU usage
CPU usage of the workload should be above eight cores. A workload may be either a
multi-threaded process or a collection of single-threaded processes.
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POWER7 and POWER7+ Optimization and Tuning Guide
WPAR workloads: In general, WPAR workloads (which implicitly use WLM) can be
optimized by ASO if minimum CPU and memory limits are not specified.