-
Enable PMI in the application server.
To monitor
performance data through the PMI interfaces, you must first enable
PMI through the administrative console before restarting the server.
If running in a
WebSphere® Application Server, Network Deployment environment, you must enable PMI on both the server
and on the administrative agent before restarting the server and the
administrative agent.
- Enable data collection and set the PMI monitoring level
to Extended.
The monitoring levels that determine which
data counters are enabled can be set dynamically, without restarting
the server. These monitoring levels and the data selected determine
the type of advice you obtain. The performance advisor in TPV uses
the extended monitoring level; however, the performance advisor in
TPV can use a few of the more expensive counters (to provide additional
advice) and provide advice on which counters can be enabled.
For
example, the advice pertaining to session size needs the PMI statistic
set to All. Or, you can use the PMI Custom Monitoring Level to enable
the Servlet Session Manager SessionObjectSize counter. The monitoring
of the SessionSize PMI counter is expensive, and is not in the Extended
PMI statistic set. Complete this action in one of the following ways:
- PMI settings.
- Enabling Performance Monitoring Infrastructure using
the wsadmin tool.
- In the administrative console, click Monitoring and
Tuning > Performance Viewer > Current
Activity.
- Simulate a production level load. Simulate a
realistic production load for your application, if you use the performance
advisor in a test environment, or do any other performance tuning.
The application must run this load without errors. This simulation
includes numbers of concurrent users typical of peak periods, and
drives system resources, for example, CPU and memory to the levels
that are expected in production. The performance advisor only provides
advice when CPU utilization exceeds a sufficiently high level. For
a list of IBM® business partners providing tools to drive
this type of load, see the performance: resource for learning information.
- Log performance data with TPV.
- Clicking Refresh on top of the table of advice causes
the advisor to recalculate the advice based on the current data in
the buffer.
- Tuning advice displays when the Advisor icon is chosen
in the TPV Performance Advisor. Double-click an individual message
for details. Because PMI data is taken over an interval
of time and averaged to provide advice, details within the advice
message display as averages.
Note: If the Refresh Rate is adjusted,
the Buffer Size must also be adjusted to enable sufficient data to
be collected for performing average calculations. Currently 5 minutes
of data is required. Hence, the following guidelines intend to help
you use the Tivoli Performance Advisor:
- You cannot have a Refresh Rate of more than 300 seconds.
- RefreshRate * BufferSize > 300 seconds. Buffer Size * Refresh
Rate is the amount of PMI data available in memory and it must be
greater than 300 seconds.
- For the Tivoli Performance Advisor to work properly
with TPV logs, the logs must be at least 300 seconds of duration.
For more information about configuring user and logging settings
of TPV, refer to the configuring TPV settings information.
- Update the product configuration for improved performance,
based on advice. Because Tivoli Performance Viewer refreshes
advice at a single instant in time, take the advice from the peak
load time. Although the performance advisors attempt to
distinguish between loaded and idle conditions, misleading advice
might be issued if the advisor is enabled while the system is ramping
up or down. This result is especially likely when running short tests.
Although the advice helps in most configurations, there might be situations
where the advice hinders performance. Because of these conditions,
advice is not guaranteed. Therefore, test the environment with the
updated configuration to ensure it functions and performs well.
Over
a period of time the advisor might issue differing advice. The differing
advice is due to load fluctuations and run-time state. When differing
advice is received, you need to look at all advice and the time period
over which it was issued. You must take advice during the time that
most closely represents the peak production load.
Performance
tuning is an iterative process. After applying advice, simulate a
production load, update the configuration that is based on the advice,
and retest for improved performance. This procedure is continued until
optimal performance is achieved.