Gathering all events from one class

Now we'll gather all events from only one class, _NTO_TRACE_THREAD. This class is arbitrarily chosen to demonstrate filtering by classes; there's nothing particularly special about this class versus any other. For a full list of the possible classes, see Classes and events in the Events and the Kernel chapter in this guide.

Here's the source, one_class.c:

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#ifdef __USAGE
%C - instrumentation example

%C  - example that illustrates the very basic use of
      the TraceEvent() kernel call and the instrumentation
      module with tracelogger in a daemon mode.

      Only events from the thread class (_NTO_TRACE_THREAD)
      are monitored (intercepted).

      In order to use this example, start the tracelogger
      in the daemon mode as:

      tracelogger -n iter_number -d1

      with iter_number = your choice of 1 through 10

      After you start the example, the tracelogger (daemon)
      will log the specified number of iterations and then
      terminate. There are no messages printed upon successful
      completion of the example. You can view the intercepted
      events with the traceprinter utility.

      See accompanied documentation and comments within
      the sample source code for more explanations.

#include <sys/trace.h>

#include "instrex.h"

int main(int argc, char **argv)
     * Just in case, turn off all filters, since we
     * don't know their present state - go to the
     * known state of the filters.

     * Intercept only thread events

     * Start tracing process
     * During the tracing process, the tracelogger (which
     * is being executed in daemon mode) will log all events.
     * You can specify the number of iterations (i.e., the
     * number of kernel buffers logged) when you start tracelogger.
    TRACE_EVENT(argv[0], TraceEvent(_NTO_TRACE_START));

     * The main() of this execution flow returns.
     * However, the main() function of the tracelogger
     * will return after registering the specified number
     * of events.
    return (0);

Compile it, and then run tracelogger in one window:

tracelogger -d1 -n 3 -f one_class.kev

and run the compiled program in another:


The trace data is in one_class.kev; to examine it, type:

traceprinter -f one_class.kev | less

The output from traceprinter will look something like this:

TRACEPRINTER version 1.02
       TRACE_FILE_NAME:: one_class.kev
            TRACE_DATE:: Wed Jun 24 10:55:05 2009
       TRACE_VER_MAJOR:: 1
       TRACE_VER_MINOR:: 01
        TRACE_ENCODING:: 16 byte events
       TRACE_BOOT_DATE:: Tue Jun 23 11:47:46 2009
  TRACE_CYCLES_PER_SEC:: 736629000
         TRACE_CPU_NUM:: 1
        TRACE_NODENAME:: localhost
     TRACE_SYS_RELEASE:: 6.4.1
     TRACE_SYS_VERSION:: 2009/05/20-17:35:56EDT
         TRACE_MACHINE:: x86pc
TRACE_TRACELOGGER_ARGS:: tracelogger -d1 -n 3 -f one_class.kev
t:0x002c4d55 CPU:00 CONTROL: BUFFER sequence = 37, num_events = 714
t:0x002c4d55 CPU:00 THREAD  :THCREATE      pid:1 tid:1
t:0x002c5531 CPU:00 THREAD  :THREADY       pid:1 tid:1 priority:0 policy:1
t:0x002c5bbe CPU:00 THREAD  :THCREATE      pid:1 tid:2
t:0x002c5cd2 CPU:00 THREAD  :THRECEIVE     pid:1 tid:2 priority:255 policy:2
t:0x002c6185 CPU:00 THREAD  :THCREATE      pid:1 tid:3
t:0x002c6272 CPU:00 THREAD  :THRECEIVE     pid:1 tid:3 priority:255 policy:2
t:0x002c64eb CPU:00 THREAD  :THCREATE      pid:1 tid:4
t:0x002c65d8 CPU:00 THREAD  :THRECEIVE     pid:1 tid:4 priority:10 policy:2
t:0x002c67fc CPU:00 THREAD  :THCREATE      pid:1 tid:5
t:0x002c68ea CPU:00 THREAD  :THRECEIVE     pid:1 tid:5 priority:255 policy:2
t:0x002c6bae CPU:00 THREAD  :THCREATE      pid:1 tid:7
t:0x002c6c9b CPU:00 THREAD  :THRECEIVE     pid:1 tid:7 priority:10 policy:2
t:0x002c6f03 CPU:00 THREAD  :THCREATE      pid:1 tid:8
t:0x002c6ff0 CPU:00 THREAD  :THRECEIVE     pid:1 tid:8 priority:10 policy:2
t:0x002c72ec CPU:00 THREAD  :THCREATE      pid:1 tid:10
t:0x002c73d9 CPU:00 THREAD  :THRECEIVE     pid:1 tid:10 priority:10 policy:2
t:0x002c7665 CPU:00 THREAD  :THCREATE      pid:1 tid:11
t:0x002c7752 CPU:00 THREAD  :THRECEIVE     pid:1 tid:11 priority:10 policy:2
t:0x002c7a9d CPU:00 THREAD  :THCREATE      pid:1 tid:12
t:0x002c7b8a CPU:00 THREAD  :THRECEIVE     pid:1 tid:12 priority:10 policy:2
t:0x002c7e44 CPU:00 THREAD  :THCREATE      pid:1 tid:15
t:0x002c7f31 CPU:00 THREAD  :THRECEIVE     pid:1 tid:15 priority:10 policy:2
t:0x002c81a2 CPU:00 THREAD  :THCREATE      pid:1 tid:20
t:0x002c828f CPU:00 THREAD  :THRECEIVE     pid:1 tid:20 priority:10 policy:2
t:0x002c88e3 CPU:00 THREAD  :THCREATE      pid:2 tid:1
t:0x002c89d3 CPU:00 THREAD  :THREPLY       pid:2 tid:1 priority:10 policy:3
t:0x002c8fad CPU:00 THREAD  :THCREATE      pid:4099 tid:1
t:0x002c909a CPU:00 THREAD  :THRECEIVE     pid:4099 tid:1 priority:10 policy:3
t:0x002c95b7 CPU:00 THREAD  :THCREATE      pid:4100 tid:1
t:0x002c96a4 CPU:00 THREAD  :THRECEIVE     pid:4100 tid:1 priority:10 policy:3
t:0x002c9b6e CPU:00 THREAD  :THCREATE      pid:4101 tid:1
t:0x002c9ccd CPU:00 THREAD  :THSIGWAITINFO pid:4101 tid:1 priority:10 policy:3


Notice that we've significantly reduced the amount of output.