dtrace - Dtrace compatible user application static probe generation tool.
Contents
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/HowToReportBugsDTRACE(1)
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.
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-stest.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));
Name
dtrace - Dtrace compatible user application static probe generation tool.
Options
-h generate a systemtap header file.
-G generate a systemtap probe definition object file.
-ofile
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.
-Ifile
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.
See Also
stap(1), stappaths(7)
Semaphores
Semaphores are flag variables used by probes as a way of bypassing potentially costly processing to pre‐
pare 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 sema‐
phore 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.
Synopsis
dtrace-sfile [OPTIONS]
