dtrace

DTRACE(1)                    General Commands Manual                   DTRACE(1)



NAME
       dtrace - Dtrace compatible user application static probe generation tool.



SYNOPSIS
       dtrace -s file [OPTIONS]


DESCRIPTION
       The dtrace command converts probe descriptions defined in file.d into a
       probe header file via the -h option or a probe description file via the
       -G option.


OPTIONS
       -h     generate a systemtap header file.


       -G     generate a systemtap probe definition object file.


       -o file
              is the name of the output file.  If the -G option is given then
              the output file will be called file.o; if the -h option is given
              then the output file will be called file.h.


       -C     run the cpp preprocessor on the input file when the -h option is
              given.


       -I file
              give this include path to cpp when the -C option is given.


       -k     keep temporary files, for example the C language source for the -G
              option.


EXAMPLES
       Systemtap is source compatible with dtrace user application static probe
       support.  Given a file test.d containing:

              provider sdt_probes
              {
                probe test_0 (int type);
                probe test_1 (struct astruct node);
              };
              struct astruct {int a; int b;};

       Then the command "dtrace -s test.d -G" will create the probe definition
       file test.o and the command "dtrace -stest.d -h" will create the probe
       header file test.h Subsequently the application can use the generated
       macros this way:

              #include "test.h"
               ...
              struct astruct s;
               ...
              SDT_PROBES_TEST_0(value);
               ...
              if (SDT_PROBES_TEST_1_ENABLED())
                  SDT_PROBES_TEST_1(expensive_function(s));



SEMAPHORES
       Semaphores are flag variables used by probes as a way of bypassing
       potentially costly processing to prepare arguments for probes that may
       not even be active.  They are automatically set/cleared by systemtap when
       a relevant script is running, so the argument setup cost is only paid
       when necessary.  These semaphore variables are defined within the the
       "test.o" object file, which must therefore be linked into an application.

       Sometimes, semaphore variables are not necessary nor helpful.  Skipping
       them can simplify the build process, by omitting the extra "test.o" file.
       To skip dependence upon semaphore variables, include "<sys/sdt.h>" within
       the application before "test.h":

              #include <sys/sdt.h>
              #include "test.h"
               ...
              struct astruct s;
               ...
              SDT_PROBES_TEST_0(value);
               ...
              if (SDT_PROBES_TEST_1_ENABLED())
                 SDT_PROBES_TEST_1(cheap_function(s));

       In this mode, the ENABLED() test is fixed at 1.


SEE ALSO
       stap(1),
       stappaths(7)



BUGS
       Use the Bugzilla link of the project web page or our mailing list.
       http://sourceware.org/systemtap/, <systemtap@sourceware.org>.

       error::reporting(7stap),
       https://sourceware.org/systemtap/wiki/HowToReportBugs



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