The performance advisor in Tivoli Performance Viewer (TPV)
provides advice to help tune systems for optimal performance and provides
recommendations on inefficient settings by using the collected Performance
Monitoring Infrastructure (PMI) data.
About this task
Obtain advice by clicking
Performance advisor in TPV.
The performance advisor in TPV provides more extensive advice than
the
Runtime Performance Advisor.
For example, TPV provides advice on setting the dynamic cache size,
setting the Java virtual machine (JVM) heap size and using the DB2
Performance Configuration wizard.
Enable PMI in the application server as described in the Enabling PMI using the administrative console article.
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 Network Deployment environment, you must enable PMI on both the
server and on the node agent before restarting the server and the
node 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:
- Performance Monitoring Infrastructure settings.
- Enabling Performance Monitoring Infrastructure using the
wsadmin tool.
Tivoli® Performance
Viewer can monitor up to 20 counters at one time.
- 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 article, Performance: Resources for learning in the subsection
of Monitoring performance with third party tools.
- 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 article.
- 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.