HP-UX Workload Manager Toolkits User's Guide

HP-UX WLM Oracle Database Toolkit: Providing Database Metrics to WLM
How do I use the metrics?
Chapter 2 59
• The proxy transaction is of significant duration.
The wlmoradc tool uses an SQL*Plus timer that has, at most,
resolution of hundredths of seconds. However, proxy transactions of
less than approximately 0.2 seconds may experience instability,
especially if the overall volume of transactions is low. This is a
guideline, not a hard limit, but take time to establish good baseline
measurements if the length of the proxy transaction is very short.
Because of the length of UNIX timeslices and measurement errors
for very short duration events, also consider using the cntl_smooth
keyword in your WLM configuration to add stability to short
duration measurements.
• The proxy transaction should be a small percentage of the total
instance work.
Be careful that the proxy transaction does not consume too much
time. A CPU-sensitive transaction must be consuming CPU
resources, so a proxy transaction should be selected that does not
consume too large a percentage of the instance’s resources. You do
not want your measurement of the performance to negatively affect
the instance’s performance.
For example, if a given proxy ‘SELECT X from table Y’ is used every
30 seconds to gauge an instance’s performance and 10,000 other
similar queries are done during that period, the proxy’s resource use
is probably a very small percentage of the overall work. However, for
a system where table Y is extremely large and only ten transactions
are completed in the 30 seconds, using the proxy may be too great a
percentage of the work. In this case, you should consider performing
some smaller SELECT or executing the proxy less frequently than 30
seconds.