Rational Team Concert for z/OS performance impact of Java JFS API adoption in 4.0.6

Introduction

This report compares the performance of RTC for z/OS of version 4.0.6 to the previous 4.0.5 release.

RTC for z/OS v4.0.6 includes an enhancement by adopting the Java JFS API for some of the queries.

The test objective is to ensure there is no regression and verify the performance improvement for the new Java JFS API adoption.

Disclaimer

The information in this document is distributed AS IS. The use of this information or the implementation of any of these techniques is a customer responsibility and depends on the customer’s ability to evaluate and integrate them into the customer’s operational environment. While each item may have been reviewed by IBM for accuracy in a specific situation, there is no guarantee that the same or similar results will be obtained elsewhere. Customers attempting to adapt these techniques to their own environments do so at their own risk. Any pointers in this publication to external Web sites are provided for convenience only and do not in any manner serve as an endorsement of these Web sites. Any performance data contained in this document was determined in a controlled environment, and therefore, the results that may be obtained in other operating environments may vary significantly. Users of this document should verify the applicable data for their specific environment.

Performance is based on measurements and projections using standard IBM benchmarks in a controlled environment. The actual throughput or performance that any user will experience will vary depending upon many factors, including considerations such as the amount of multi-programming in the user’s job stream, the I/O configuration, the storage configuration, and the workload processed. Therefore, no assurance can be given that an individual user will achieve results similar to those stated here.

This testing was done as a way to compare and characterize the differences in performance between different versions of the product. The results shown here should thus be looked at as a comparison of the contrasting performance between different versions, and not as an absolute benchmark of performance.

What our tests measure

We use predominantly automated tooling such as Rational Performance Tester (RPT) to simulate a workload normally generated by client software such as the Eclipse client or web browsers. All response times listed are those measured by our automated tooling and not a client.

The diagram below describes at a very high level which aspects of the entire end-to-end experience (human end-user to server and back again) that our performance tests simulate. The tests described in this article simulate a segment of the end-to-end transaction as indicated in the middle of the diagram. Performance tests are server-side and capture response times for this segment of the transaction.

Findings

Based on the test data, performance of the RTC for z/OS has an improvement in Enterprise Extensions dependency build preprocessing speeds from 4.0.5 to 4.0.6:

• In the scenario of the incremental build (request build after changing all the copybook files), the "Collecting buildable files" activity in preprocessing time improved about 25%, and result in an about 5% improvement in total run time.

For other scenarios performance stayed consistent between the two versions.

Topology

The tests are executed in a Single Tier Topology infrastructure like the one in the following diagram:

The RTC server was set up based on WebSphere and DB2 on Linux for System z. The build machine with Rational Build Agent was on zOS.

Methodology

The sample project for the test was Mortgage*100 which is 100 duplicates of the Mortgage sample application .

In the repository the source code is stored in one stream with one single component which includes 4 zComponent Projects.

Each test scenario is executed twice against the two versions.

Test Scenarios

Results

Run duration

These data tables show the run duration comparing between 4.0.6 and 4.0.5 with the test start and completion time.

In the scenario of the incremental build (request build after changing all the copybook files), the total run time has an improvement about 5% , which is a result of performance improvements in incremental build preprocessing speeds of version 4.0.6.

In version 4.0.6, Suppress build map links option is added to promotion definition. Before 4.0.6, build map links were automatically published to the build result (unless manually set additional build property). In 4.0.6, A new check box on the promotion definition allows you to turn this feature off, which improves processing speed. By default, new definitions will not publish build map links.

Build Activities

These data tables display the detailed build activity run time. In version 4.0.6, there is performance improvements in incremental build preprocessing speeds.

In the scenario of the incremental build (request build after changing all the copybook files), the "Collecting buildable files" time in preprocessing time improved about 25%. The improvements reflected the change of build map queries to adopt the Java JFS API.

CPU and Memory for RTC server

This graph shows CPU and memory utilization for RTC server, data is collected by NMON tool. 4.0.5 and 4.0.6 show similar CPU and memory utilization.

CPU and Memory for Build Agent

This graph shows CPU and memory utilization for Build Forge Agent on ZOS machine, data is collected by RMF tool. 4.0.5 and 4.0.6 show similar CPU and memory utilization.

Appendix A - Key Tuning Parameters

 -Xmn512m -Xgcpolicy:gencon -Xcompressedrefs -Xgc:preferredHeapBase=0x100000000
 -Xmx4g -Xms4g

* hard nofile 120000                    
* soft nofile 120000

About the authors

SuHui

Questions and comments:

• What other performance information would you like to see here?
• Do you have performance scenarios to share?
• Do you have scenarios that are not addressed in documentation?
• Where are you having problems in performance?

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