2. PERFORMANCE REPORTING ANALYSIS › 2.6 PR/SM LPAR Performance Analysis › 2.6.4 Usage Guidelines › 2.6.4.1 CEC Configuration Tuning

2.6.4.1 CEC Configuration Tuning

In tuning the CEC configuration, you should be aware of high
levels of contention for shared processor resources.  The
overhead required for PR/SM to manage and allocate processor
resources on behalf of the logical partitions can grow to as
much as 12% as more processors are shared and as contention
for their use increases.

The PR/SM CEC Summary report described in section 2.6.3.2
provides a key indicator of PR/SM overhead in the form of the
Percent of CEC Consumed.  This measure is particularly useful
when all physical processors are being shared, as it then
reflects the overall utilization of processor resources in
the complex.  However, if dedicated processors are included
in the configuration, each such processor is considered as
100% utilized (since it is not available to the CEC for
sharing with other logical partitions (LPARs)).

Significant benefits can be derived from the use of dedicated
processors.  If multiple workloads that previously ran
simultaneously on a multi-processor system can be
re-distributed such that they run separately on multiple
LPARs each with a dedicated CP, increased throughput is
possible due to the reduced overhead that occurs because a
single SCP is not trying to juggle multiple processors.