Dynamic Tracing Guide
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Chapter 14

dtrace(1M) Utility

The dtrace(1M) command is a generic front-end to the DTrace facility. The command implements a simple interface to invoke the D language compiler, the ability to retrieve buffered trace data from the DTrace kernel facility, and a set of basic routines to format and print traced data. This chapter provides a complete reference for the dtrace command.

Description

The dtrace command provides a generic interface to all of the essential services provided by the DTrace facility, including:

  • Options to list the set of probes and providers currently published by DTrace

  • Options to enable probes directly using any of the probe description specifiers (provider, module, function, name)

  • Options to run the D compiler and compile one or more D program files or programs written directly on the command-line

  • Options to generate anonymous tracing programs (see Chapter 36, Anonymous Tracing)

  • Options to generate program stability reports (see Chapter 39, Stability)

  • Options to modify DTrace tracing and buffering behavior and enable additional D compiler features (see Chapter 16, Options and Tunables)

dtrace can also be used to create D scripts by using it in a #! declaration to create an interpreter file (see Chapter 15, Scripting). Finally, you can use dtrace to attempt to compile D programs and determine their properties without actually enabling any tracing using the -e option, described below.

Options

The dtrace command accepts the following options:

dtrace [-32 | -64 ] [-aACeFGHlqSvVwZ ] [-b bufsz ] [-c cmd ] [-D name [=def ] ] [-I path ] [-L path ] [-o output ] [-p pid ] [-s script ] [-U name ] [-x arg [=val ] ] [-X [a | c | s | t ] ] [-P provider [ [predicate ] action ] ] [-m [provider: ]module [ [predicate ] action ] ] [-f [ [provider: ] module: ] func [ [predicate ] action ] ] [-n [ [ [provider: ] module: ] func: ] name [ [predicate ] action ] ] [-i probe-id [ [predicate ] action ] ]

where predicate is any D predicate enclosed in slashes / / and action is any D statement list enclosed in braces { } according to the previously described D language syntax. If D program code is provided as an argument to the -P, -m, -f, -n, or -i options this text must be appropriately quoted to avoid interpretation by the shell. The options are as follows:

-32, -64

The D compiler produces programs using the native data model of the operating system kernel. You can use the isainfo(1) -b command to determine the current operating system data model. If the -32 option is specified, dtrace will force the D compiler to compile a D program using the 32-bit data model. If the -64 option is specified, dtrace will force the D compiler to compile a D program using the 64-bit data model. These options are typically not required as dtrace selects the native data model as the default. The data model affects the sizes of integer types and other language properties. D programs compiled for either data model may be executed on both 32-bit and 64-bit kernels. The -32 and -64 options also determine the ELF file format (ELF32 or ELF64) produced by the -G option.

-a

Claim anonymous tracing state and display the traced data. You can combine the -a option with the -e option to force dtrace to exit immediately after consuming the anonymous tracing state rather than continuing to wait for new data. See Chapter 36, Anonymous Tracing for more information about anonymous tracing.

-A

Generate driver.conf(4) directives for anonymous tracing. If the -A option is specified, dtrace compiles any D programs specified using the -s option or on the command-line and constructs a set of dtrace(7D) configuration file directives to enable the specified probes for anonymous tracing (see Chapter 36, Anonymous Tracing) and then exits. By default, dtrace attempts to store the directives to the file /kernel/drv/dtrace.conf. This behavior can be modified using the -o option to specify an alternate output file.

-b

Set principal trace buffer size. The trace buffer size can include any of the size suffixes k, m, g, or t as described in Chapter 36, Anonymous Tracing. If the buffer space cannot be allocated, dtrace attempts to reduce the buffer size or exit depending on the setting of the bufresize property.

-c

Run the specified command cmd and exit upon its completion. If more than one -c option is present on the command line, dtrace exits when all commands have exited, reporting the exit status for each child process as it terminates. The process-ID of the first command is made available to any D programs specified on the command line or using the -s option through the $target macro variable. Refer to Chapter 15, Scripting for more information on macro variables.

-C

Run the C preprocessor cpp(1) over D programs before compiling them. Options can be passed to the C preprocessor using the -D, -U, -I, and -H options. The degree of C standard conformance can be selected using the -X option. Refer to the description of the -X option for a description of the set of tokens defined by the D compiler when invoking the C preprocessor.

-D

Define the specified name when invoking cpp(1) (enabled using the -C option). If an equals sign (=) and additional value are specified, the name is assigned the corresponding value. This option passes the -D option to each cpp invocation.

-e

Exit after compiling any requests and consuming anonymous tracing state (-a option) but prior to enabling any probes. This option can be combined with the -a option to print anonymous tracing data and exit, or it can be combined with D compiler options to verify that the programs compile without actually executing them and enabling the corresponding instrumentation.

-f

Specify function name to trace or list (-l option). The corresponding argument can include any of the probe description forms provider:module:function, module:function, or function. Unspecified probe description fields are left blank and match any probes regardless of the values in those fields. If no qualifiers other than function are specified in the description, all probes with the corresponding function are matched. The -f argument can be suffixed with an optional D probe clause. More than one -f option may be specified on the command-line at a time.

-F

Coalesce trace output by identifying function entry and return. Function entry probe reports are indented and their output is prefixed with ->. Function return probe reports are unindented and their output is prefixed with <-.

-G

Generate an ELF file containing an embedded DTrace program. The DTrace probes specified in the program are saved inside of a relocatable ELF object that can be linked into another program. If the -o option is present, the ELF file is saved using the pathname specified as the argument for this operand. If the -o option is not present and the DTrace program is contained in a file whose name is filename.s, then the ELF file is saved using the name file.o; otherwise the ELF file is saved using the name d.out.

-H

Print the pathnames of included files when invoking cpp(1) (enabled using the -C option). This option passes the -H option to each cpp invocation, causing it to display the list of pathnames, one per line, to stderr.

-i

Specify probe identifier to trace or list (-l option). Probe IDs are specified using decimal integers as shown by dtrace -l. The -i argument can be suffixed with an optional D probe clause. More than one -i option may be specified on the command-line at a time.

-I

Add the specified directory path to the search path for #include files when invoking cpp(1) (enabled using the -C option). This option passes the -I option to each cpp invocation. The specified directory is inserted into the search path ahead of the default directory list.

-l

List probes instead of enabling them. If the -l option is specified, dtrace produces a report of the probes matching the descriptions given using the -P, -m, -f, -n, -i, and -s options. If none of these options are specified, all probes are listed.

-L

Add the specified directory path to the search path for DTrace libraries. DTrace libraries are used to contain common definitions that may be used when writing D programs. The specified path is added after the default library search path.

-m

Specify module name to trace or list (-l option). The corresponding argument can include any of the probe description forms provider:module or module. Unspecified probe description fields are left blank and match any probes regardless of the values in those fields. If no qualifiers other than module are specified in the description, all probes with a corresponding module are matched. The -m argument can be suffixed with an optional D probe clause. More than one -m option may be specified on the command-line at a time.

-n

Specify probe name to trace or list (-l option). The corresponding argument can include any of the probe description forms provider:module:function:name, module:function:name, function:name, or name. Unspecified probe description fields are left blank and match any probes regardless of the values in those fields. If no qualifiers other than name are specified in the description, all probes with a corresponding name are matched. The -n argument can be suffixed with an optional D probe clause. More than one -n option may be specified on the command-line at a time.

-o

Specify the output file for the -A , -G, and -l options, or for the traced data. If the -A option is present and -o is not present, the default output file is /kernel/drv/dtrace.conf. If the -G option is present and the -s option's argument is of the form filename.d and -o is not present, the default output file is filename.o; otherwise the default output file is d.out.

-p

Grab the specified process-ID pid, cache its symbol tables, and exit upon its completion. If more than one -p option is present on the command line, dtrace exits when all commands have exited, reporting the exit status for each process as it terminates. The first process-ID is made available to any D programs specified on the command line or using the -s option through the $target macro variable. Refer to Chapter 15, Scripting for more information on macro variables.

-P

Specify provider name to trace or list (-l option). The remaining probe description fields module, function, and name are left blank and match any probes regardless of the values in those fields. The -P argument can be suffixed with an optional D probe clause. More than one -P option may be specified on the command-line at a time.

-q

Set quiet mode. dtrace will suppress messages such as the number of probes matched by the specified options and D programs and will not print column headers, the CPU ID, the probe ID, or insert newlines into the output. Only data traced and formatted by D program statements such as trace and printf will be displayed to stdout.

-s

Compile the specified D program source file. If the -e option is present, the program is compiled but no instrumentation is enabled. If the -l option is present, the program is compiled and the set of probes matched by it is listed, but no instrumentation will be enabled. If neither -e nor -l are present, the instrumentation specified by the D program is enabled and tracing begins.

-S

Show D compiler intermediate code. The D compiler will produce a report of the intermediate code generated for each D program to stderr.

-U

Undefine the specified name when invoking cpp(1) (enabled using the -C option). This option passes the -U option to each cpp invocation.

-v

Set verbose mode. If the -v option is specified, dtrace produces a program stability report showing the minimum interface stability and dependency level for the specified D programs. DTrace stability levels are explained in further detail in Chapter 39, Stability.

-V

Report the highest D programming interface version supported by dtrace. The version information is printed to stdout and the dtrace command exits. See Chapter 41, Versioning for more information about DTrace versioning features.

-w

Permit destructive actions in D programs specified using the -s, -P, -m, -f, -n, or -i options. If the -w option is not specified, dtrace will not permit the compilation or enabling of a D program that contains destructive actions. Destructive actions are described in further detail in Chapter 10, Actions and Subroutines.

-x

Enable or modify a DTrace runtime option or D compiler option. The options are listed in Chapter 16, Options and Tunables. Boolean options are enabled by specifying their name. Options with values are set by separating the option name and value with an equals sign (=).

-X

Specify the degree of conformance to the ISO C standard that should be selected when invoking cpp(1) (enabled using the -C option). The -X option argument affects the value and presence of the __STDC__ macro depending upon the value of the argument letter:

a (default)

ISO C plus K&R compatibility extensions, with semantic changes required by ISO C. This mode is the default mode if -X is not specified. The predefined macro __STDC__ has a value of 0 when cpp is invoked in conjunction with the -Xa option.

c (conformance)

Strictly conformant ISO C, without K&R C compatibility extensions. The predefined macro __STDC__ has a value of 1 when cpp is invoked in conjunction with the -Xc option.

s (K&R C)

K&R C only. The macro __STDC__ is not defined when cpp is invoked in conjunction with the -Xs option.

t (transition)

ISO C plus K&R C compatibility extensions, without semantic changes required by ISO C. The predefined macro __STDC__ has a value of 0 when cpp is invoked in conjunction with the -Xt option.

Because the -X option affects only how the D compiler invokes the C preprocessor, the -Xa and -Xt options are equivalent from the perspective of D. Both options are provided to ease re-use of settings from a C build environment.

Regardless of the -X mode, the following additional C preprocessor definitions are always specified and valid in all modes:

  • __sun

  • __unix

  • __SVR4

  • __sparc (on SPARC® systems only)

  • __sparcv9 (on SPARC® systems only when 64–bit programs are compiled)

  • __i386 (on x86 systems only when 32–bit programs are compiled)

  • __amd64 (on x86 systems only when 64–bit programs are compiled)

  • __'uname -s'_'uname -r', replacing the decimal point in the output of uname with an underscore (_), as in __SunOS_5_10

  • __SUNW_D=1

  • __SUNW_D_VERSION=0xMMmmmuuu (where MM is the Major release value in hexadecimal, mmm is the Minor release value in hexadecimal, and uuu is the Micro release value in hexadecimal; see Chapter 41, Versioning for more information about DTrace versioning)

-Z

Permit probe descriptions that match zero probes. If the -Z option is not specified, dtrace will report an error and exit if any probe descriptions specified in D program files (-s option) or on the command-line (-P, -m, -f, -n, or -i options) contain descriptions that do not match any known probes.

Operands

Zero or more additional arguments may be specified on the dtrace command line to define a set of macro variables ($1, $2, and so on) to be used in any D programs specified using the -s option or on the command-line. The use of macro variables is described further in Chapter 15, Scripting.

Exit Status

The following exit values are returned by the dtrace utility:

0

The specified requests were completed successfully. For D program requests, the 0 exit status indicates that programs were successfully compiled, probes were successfully enabled, or anonymous state was successfully retrieved. dtrace returns 0 even if the specified tracing requests encounted errors or drops.

1

A fatal error occurred. For D program requests, the 1 exit status indicates that program compilation failed or that the specified request could not be satisfied.

2

Invalid command-line options or arguments were specified.

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