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Performance Considerations
Performance ConsiderationsPerformance Considerations
Performance Considerations
CPW
Relative performance measurements are derived from commercial processing workloads (CPW) running on iSeries
servers. CPW is representative of commercial applications, particularly those that do significant database
processing in conjunction with journaling and committment control. CPW values may not be realized in all
environments.
IBM will publish the Processor CPW value for the start-up number of processors as well as a Processor CPW value
that represents the full capacity of the server when all processors are active (Start-up + Stand-by). IBM is not
publishing Processor CPW values associated with each incremental processor activation. If needed, for capacity
planning purposes, one could calculate the approximate CPW associated with each activated processor by
subtracting the Processor CPW published for the start-up number of processors from the maximum Processor CPW
for the server and then dividing by the number of stand-by processors.
CPU Utilization
Standby processors are NOT considered within the various system functions that report CPU utilization percentages
until they are activated and assigned to a partition.
CPU percent is a calculated metric based on the amount of time the processor was active within an elapsed time.
This is normally reported as a percentage where 100% indicates the processor was busy for the entire sample
interval. When multiple processors are present, CPU time must be adjusted to be the average usage of all processors
so that utilization is always reported as the percentage of total available capacity.
5250 OLTP (“interactive”) capability is determined by the edition feature purchased. This capability is not impacted
by the number of standby processors and does not change when standby processors become active. Interactive
utilization reported as a percentage of interactive capability is not affected by the Capacity on Demand technology.
Within Management Central, this metric is called “CPU Utilization (Interactive Feature)”.
Interactive CPU utilization is also reported as a percentage of total system CPU. Within Management Central this
metric is called “CPU Utilization (Interactive Jobs)”.
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12/15/2003