Creating Custom Instruments with DTrace
The built-in instruments of the Instruments application can provide a great deal of information about the inner workings of your program. Sometimes, though, you may want to tailor the information being gathered more closely to your own code. For example, instead of gathering data every time a function is called, you might want to set conditions on when data is gathered. Alternatively, you might want to dig deeper into your own code than the built-in instruments allow. For these situations, Instruments lets you create custom instruments.
Custom instruments use DTrace for their implementation. DTrace is a dynamic tracing facility originally created by Sun and ported to Mac OS X v10.5. Because DTrace taps into the operating system kernel, you have access to low-level operation about the kernel itself and about the user processes running on your computer. Many of the built-in instruments are already based on DTrace. And even though DTrace is itself a very powerful and complex tool, Instruments provides a simple interface that gives you access to the power of DTrace without the complexity.
Important: Although the custom instrument builder simplifies the process of creating DTrace probes, you should still be familiar with DTrace and how it works before creating new instruments. Many of the more powerful debugging and data gathering actions require you to write DTrace scripts. To learn about DTrace and the D scripting language, see the Solaris Dynamic Tracing Guide, available from the OpenSolaris website. For information about the dtrace command-line tool, see dtrace man page.
Note: Several Apple applications—namely iTunes, DVD Player, and Front Row, and applications that use QuickTime—prevent the collection of data through DTrace (either temporarily or permanently) in order to protect sensitive data. Therefore, you should not run those applications when performing systemwide data collection.
The following sections show you how to create a custom instrument and how to use that instrument both with the Instruments application and the dtrace command-line tool.
Contents:
About Custom Instruments
Creating a Custom Instrument
Tips for Writing Custom Scripts
Exporting DTrace Scripts
Last updated: 2008-02-08
  |
||
|
|
|
|
| ||
Get information on Apple products.
Visit the Apple Store online or at retail locations. 1-800-MY-APPLE Copyright © 2007 Apple Inc. All rights reserved. | Terms of use | Privacy Notice |