Setting DTrace Compile-time and Runtime Options

You can tune DTrace by setting or enabling a selection of runtime or compiler options. You can set options by either using the -x command line switch when running the dtrace command, or by specifying pragma lines in D programs. If an option takes a value, follow the option name with an equal sign (=) and the option value.

Value Suffixes

Use the following optional suffixes for values that denote size or time:

  • k or K: kilobytes

  • m or M: megabytes

  • g or G: gigabytes

  • t or T: terabytes

  • ns or nsec: nanoseconds

  • us or usec: microseconds

  • ms or msec: milliseconds

  • s or sec: seconds

  • m or min: minutes

  • h or hour: hours

  • d or day: days

  • hz: number per second

Example 5-1 Enabling Options Using the DTrace Utility

The dtrace command accepts option settings on the command line by using the -x switch, for example: 

sudo dtrace -x nspec=4 -x bufsize=2g \
-x switchrate=10hz -x aggrate=100us -x bufresize=manual

Example 5-2 DTrace Pragma Lines To Enable Options in a D Program

You can set options in a D program by using #pragma D followed by the string option and the option name and value. The following are examples of valid option settings: 

#pragma D option nspec=4
#pragma D option bufsize=2g
#pragma D option switchrate=10hz
#pragma D option aggrate=100us
#pragma D option bufresize=manual