Strobe for z/OS UNIX System Services Overview
The Strobe Application Performance Management System is a product that determines how and where application time is spent in online and batch-processing environments. Strobe tracks activity by collecting several types of data and producing reports that determine how to improve an application’s performance.
Strobe for z/OS UNIX System Services enables customers to measure batch-processing and online applications that use UNIX System Services. This section describes the benefits of Strobe for z/OS UNIX System Services, outlines concepts and terminology of the Strobe product, and provides an overview of the z/OS UNIX System Services environment.
Strobe for z/OS UNIX System Services Benefits
Strobe for z/OS UNIX System Services obtains application performance information as the application executes. Strobe organizes this information into a series of reports called the Strobe Performance Profile. The Performance Profile identifies:
- CPU activity and wait time for modules running in address spaces that call z/OS UNIX System Services
- File system usage (HFS or z/FS)
- How applications use z/OS UNIX System Services.
Strobe for z/OS UNIX System Services helps you to measure, analyze, and improve the performance of applications that use z/OS UNIX System Services, enabling you to develop and maintain more efficient and responsive applications throughout the application life cycle.
The next section discusses the key concepts and terms that are central to the use of Strobe for z/OS UNIX System Services.
Concepts and Terminology
Before using Strobe for UNIX System Services, it is helpful to familiarize yourself with the basic concepts and terminology specific to Strobe. As shown in Overview of Strobe Tasks, you select the job step you want to measure and submit a measurement request.
A measurement request specifies the parameters for measuring the performance of an application. When the application is active, Strobe begins a measurement session, an interval where it collects performance data about the application while it is executing. Strobe stores measurement data in a sample dataset, a file that contains the information collected during a single measurement session. Each measurement session corresponds to one sample dataset.
After Strobe closes the sample dataset, you can use it to create the Performance Profile, a hierarchical series of reports that presents the performance data collected during a measurement session. These reports show where and how the application spends its time during execution. Examine the Performance Profile to identify performance improvement opportunities, and incorporate the appropriate changes to your source code. You can then repeat the process to see the results of your code changes, and identify other potential performance improvement opportunities that may have been masked by the initial problem.
Overview of Strobe Tasks
Overview of the z/OS UNIX System Services Environment
The z/OS UNIX System Services environment comprises a shell interface, a kernel address space, and either the Hierarchical File System (HFS) or the z/FS file system. Each component of this environment enables you to execute a number of z/OS UNIX System Services application services. The application services include support for:
- Utilities to administer and develop applications in the UNIX System Services environment
- Socket applications
- Direct telnet service based on the TCP/IP protocol
- Full-screen applications.
Each component of the z/OS UNIX System Services environment is briefly described in the following sections.
Overview of the z/OS UNIX System Services Environment
The Interactive Shell Interface
The interactive shell interface is an execution environment that processes requests for online or batch processing applications and services.
Customers access the shell interface, use the Time Sharing Option Extension (TSO/E), the BPXBATCH utility, the rlogin command, or the application itself to issue shell commands or invoke utilities, as shown in Overview of the z/OS UNIX System Services Environment. Once accessed, the shell interface interprets and executes the shell commands within a shell script. A shell script, which is a file of your shell commands that becomes executable when you specify a file name, creates a parent process in an address space to execute the program.
Once parent processes are created in an address space, they may create additional forked or spawned child processes to carry out program commands. The fork command creates a process in a separate address space. The spawn command creates a process in the same address as the parent (local spawn) or in its own address space (non-local spawn).
The Kernel Address Space
The kernel address space acts as an interface between the operating system and the hardware and provides services for system calls, file support, and device drivers. It contains the MVS support for z/OS UNIX System Services, including programs for I/O, management, and communication.
A program or a job invoked from a TSO/E session requests kernel services by using C/C++ functions, shell commands (after invoking the shell), or callable services. We recommend that you do not measure the kernel address space.
The z/OS UNIX System Services File System
z/OS UNIX System Services stores its data and program files into a Hierarchical File System (HFS) or the High Performance z/FS file system. Files are organized in a hierarchy and stored in directories.
The z/OS UNIX System Services file system includes data and executable files. Its file system and the traditional MVS file system are compatible; you use TSO/E shell commands to copy, store, and link files between the z/OS UNIX System Service file system and z/OS datasets. In addition, you can use the z/OS UNIX System Services Network File System (NFS) Feature to issue commands from your z/OS UNIX System Services workstation to read or write data from an MVS dataset.
The NFS Feature mounts z/OS UNIX System Services files, datasets, or directories into an empty directory at your workstation and links them to an MVS dataset. After you mount or link files, you can edit, run, or write to another file from your workstation. This feature allows you to access remote files as though they were local to your workstation.
Customers access z/OS UNIX System Services files by:
- Entering shell commands on the TSO/E command line
- Submitting JCL statements or BPXBATCH that specify the name of the file in the HFS directory.
Where to find more information
You can find detailed instructions for submitting and managing measurement requests and creating Performance Profiles in the Strobe/ISPF Online Tutorial and the Using-Strobe-to-measure-online-applications-and-batch-programs. For more information on interpreting Performance Profiles, refer to the Using-the-Strobe-Application-Performance-Measurement-System.