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HP SPT/XL's Main Functions HP SPT/XL follows a collection-and-analysis approach to program tuning. During collection, sampling and tracing techniques are used to gather data. Analysis provides online reports used for evaluating the data. Collecting Data HP SPT/XL divides application resource use into two categories of execution: time spent in application code and time spent in system code on behalf of the user requesting a system service by calling an intrinsic. Two different data collection techniques are used to profile these categories. See appendix C for a more detailed discussion of HP SPT/XL's data collection function. To profile the time spent in application code, HP SPT/XL monitors a program at frequent intervals and through sampling identifies the instruction address being processed. This instruction address is stored in the HP SPT/XL logfile so later analysis can provide information on where the program spent its processing time. A tracing technique is used to profile the time spent in system code on behalf of intrinsics invoked by the application. Trace data is generated at the entry and exit of most intrinsic calls. (See appendix D for a list of the intrinsics traced.) This trace data consists of metrics such as frequency of execution, time consumed, and so on. This trace data shows how an application utilizes system intrinsics and how these are used to process files and databases. HP SPT/XL allows you to collect data on an application program that is already executing, or you can start the program from within HP SPT/XL. No special library linking is required.
NOTE See the HP SPT/XL User's Manual: Collection Software for details on how to use HP SPT/XL's data collection function.
Analyzing Data HP SPT/XL reports on the data collected as described above. In the analysis phase, you profile the monitored program either as a unit or by dividing it into logical unit-of-work transactions. You can refine and redefine transactions as you analyze your program with HP SPT/XL. Information on the following is available: * Intrinsics * Files used * TurboIMAGE databases used * Program code and executing library code * Transactions Comparing Data HP SPT/XL includes a Compare function, so you can compare tuning results with previously collected data as you make adjustments to algorithms and data structures. HP SPT/XL allows you to compare two monitored executions of an application to identify where response time or processing time increased or decreased. By making a benchmark run when conditions are optimal and comparing this with runs made with the application in production mode, you can see how the application performance differs from what you might have expected. There are several places in the HP SPT/XL analyzer where you can use this compare feature. * At the Transaction List display you can choose to compare transaction process times for two different logfiles, for example, one logfile might be the initial execution of the application and the other might contain data collected after optimization of the application. * You can also compare performance data for a particular transaction type from two different logfiles. You can do this from the Transaction Intrinsic Profile screen. * You can compare two instances of a transaction within the same logfile at the Individual Transaction List or Individual Transaction Percentiles screens. This will allow you to further analyze inconsistency in response times for a given transaction.