IBM Power System POWER7 Series, Optimization And Tuning Manual

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Chapter 4. AIX
85
The ASO daemon has a maximum system usage impact of 3%. ASO also monitors the
system for situations that are not suitable for certain types of performance optimization. In
such situations, ASO
hibernates those optimization strategies, waking up occasionally to
check for a change in environment (for more information about this topic, see 4.2.3,
“Workloads” on page 87 and “System requirements” on page 90).
The primary design goal of ASO/DSO is to act only when it is reasonably certain that the
result is an improvement in workload performance.
Figure 4-1 illustrates the basic ASO framework. ASO uses information from the AIX kernel
and the POWER7 Performance Monitoring Unit (PMU)
3, 4, 5
to perform long-term runtime
analysis with the aim of improving workload performance.
Figure 4-1 Basic ASO architecture that shows an optimization flow on a POWER7 system
Optimization strategies
Two optimization strategies are provided with ASO:
򐂰
Cache affinity optimization
򐂰
Memory affinity optimization
DSO adds two more optimizations to the ASO framework:
򐂰 Large page optimization
򐂰 Memory prefetch optimization
The first version that was released in 4Q 2011 included the cache and memory affinity
optimizations. The 4Q 2012 version introduces the large page and data stream prefetch
optimization types.
3
Commonly Used Metrics For Performance Analysis, available at::
http://www.power.org/documentation/commonly-used-metrics-for-performance-analysis/
(registration
required)
4
Comprehensive PMU Event Reference - POWER7, available at:
http://www.power.org/documentation/comprehensive-pmu-event-reference-power7/
(registration required)
5
Hardware performance monitor APIs and tools, available at:
http://publib.boulder.ibm.com/infocenter/aix/v7r1/topic/com.ibm.aix.prftools/doc/prftools/idprftools
_monitor.htm
AIX 7.1
POWER7
Workloads
Kernel Data
Resource Allocation
Performance Monitoring Unit
Monitor
Workloads
Optimize
ASO
Long Term Analysis