The Xcode tools includes several graphical applications and command-line tools for gathering performance metrics. The following sections introduce the available tools and tell you when you might use them.
Installing the Apple Tools
The Apple performance tools are installed as part of the Xcode tools. This package ships on a CD that comes with retail copies of OS X. You can also download the Xcode tools for free from the Apple Developer website.
To install Xcode Tools, double-click the installer package found on the Xcode Tools CD or that you downloaded from the web. By default, the installer creates a
/Developer directory on the boot volume of your hard drive and installs applications, documentation, examples, and other files in this directory. In Xcode 3.0 and later, the installer lets you specify a custom installation directory so that you can have multiple versions of the tools on your computer.
Most of the applications with a graphical user interface have online help available through the Help menu. For information about these tools, see OS X Man Pages.
Although Xcode comes with numerous applications for gathering performance data, there are a few that you will use more frequently than others. These tools can be used to gather data for both Mac apps and iPhone applications. The following sections describe these tools and the features they provide.
Introduced in OS X v10.5, the Instruments application combines a set of powerful analysis tools with an easy-to-use graphical user interface. Instruments provides unprecedented information about the runtime behavior of your application. Rather than show only one aspect of your program at a time, you configure each analysis session with one or more “instruments”, each of which gathers information about a particular performance metric. The data from all instruments is shown side-by-side, making it easier to correlate the data from one instrument to another and detect trends in your application’s behavior.
Among the types of metrics you can gather with the Instruments application are the following:
The performance of Core Data–based applications
Information about file system reads, writes, and other operations
Statistics relating to garbage-collected code
Information about graphics operations and performance
Statistics about object and other memory-related allocations
Information about memory leaks
Statistical samples of your application at runtime
Information about process-specific and system-level activity
Information about Java thread activity
Information about events dispatched by Cocoa
For a quick example of how to use the Instruments application, see Using Instruments. For detailed information about the Instruments application, see Instruments User Guide.
Instruments is not the only analysis tool that you can use to gather data about the performance of your program. Most of the analysis tools are geared towards finding specific types of performance problems.
Table 3-1 lists the analysis tools installed with the Xcode Tools. (These tools are not able to analyze applications running in iOS.) Applications such as MallocDebug are installed in the <Xcode>
/Applications/Performance Tools directory, where <Xcode> is the root directory of your Xcode installation. Command-line tools, such as
leaks, are installed in
Monitoring tools are passive tools that gather data automatically. To use these tools, leave them running while you exercise the features of your program. You can then analyze the data generated by these tools to gain a better understanding of your program’s performance characteristics. Some programs, like Spin Control, should be left running all the time. Most others can be launched and terminated as needed to gather performance information.
Table 3-2 lists the monitoring tools installed with the Xcode Tools in OS X. (These tools are not able to monitor applications running in iOS.) Applications such as BigTop and Spin Control are installed in the <Xcode>
/Applications/Performance Tools directory hierarchy, where <Xcode> is the root directory of your Xcode installation. The Activity Monitor tool is installed in the
/Applications/Utilities directory. Command-line tools, such as
top, are installed in
Displays common usage statistics relating to memory and CPU usage for the currently running processes. You can also initiate the sampling of a process from this application. This tool provides information that is similar to that of the
Displays system statistics, such as CPU, disk, network and memory usage graphically over time. You can monitor a single process or all processes. This tool provides information that is similar to that of the
Shows screen updates in real time by briefly flashing the areas being redrawn. You can use this tool to analyze your application’s drawing behavior.
Samples programs that cause the spinning cursor to appear. Leave this program running in the background to catch unresponsive applications at critical moments.
Graphically displays activity across a range of threads. It provides color-coded timeline views of thread activity and can display backtraces of activity at specific points in time. (Available in OS X v10.5 and earlier.)
Displays an ongoing list of file-system activity, as generated by page faults and calls to file-system functions. You can use this tool to understand the file access patterns of your program.
Displays an ongoing list of system call and page fault statistics.
Displays common system usage statistics relating to memory and CPU usage for the currently running processes. This tool updates the information dynamically so that you can see trends at runtime.
Hardware Analysis Tools
The CHUD Tools include additional applications for doing hardware and low-level software analysis in OS X. (These tools are not able to analyze hardware running iOS.) Table 3-3 lists the tools that are part of this package and provides a brief overview of their purpose. The graphical applications are installed in <Xcode>
/Applications/Performance Tools/CHUD directory, where <Xcode> is the root directory of your Xcode installation. The command-line tools are installed in the
/usr/bin directory. All of the tools are included with the Xcode Tools.
A command-line tool that analyzes TT6E instruction traces and presents detailed analyses and histograms. You can use this tool to detect bad instruction sequences, such as misaligned operands, data dependency stalls, and spilled loads.
For information about using the CHUD tools, see online help for a particular tool. Documentation for some CHUD tools is also installed in the <Xcode>
/Documentation/CHUD directory, where <Xcode> is the root directory of your Xcode installation.
Additional Command-Line Tools
Table 3-4 lists some additional command-line tools that you can use to monitor and analyze performance in OS X. (These tools are not able to monitor and analyze applications running in iOS.) These tools are located in the
/usr/bin/ directory and must be run from a command-line prompt. Most are installed along with the Xcode Tools. For information about these tools, see OS X Man Pages.
Converts back and forth between a symbol name and the numeric address of that symbol in a running executable.
Displays the C-structures from an object file along with their member offset values.
Produces execution profiles based on an execution analysis of a program.
Displays the symbol table information for one or more object files.
Displays the contents of a Mach-O executable in a more human-readable form
Displays information about the logical pages of a Mach-O executable file.
Parses the C structures from an object file and displays them along with their member offset values.
Produces an execution profile based on the execution analysis of a program.
Displays Mach virtual memory statistics, including the number of active, inactive, wired, and free pages. This tool also displays page fault and other activity information.