Data interpretation

The data of an event includes a high-precision timestamp as well as the ID number of the CPU on which the event was generated. This information helps you easily diagnose difficult timing problems, which are more likely to occur on multiprocessor systems.

The event format also includes the CPU platform (e.g., x86, ARM, etc.) and endian type, which facilitates remote analysis (whether in real time or offline). Using a data interpreter, you can view the data output in various ways, such as:

a timestamp-based linear presentation of the entire system
a “running” view of only the active threads/processes
a state-based view of events per process/thread.

The linear output from the data interpreter might look something like this:

TRACEPRINTER version 0.94
 -- HEADER FILE INFORMATION --
       TRACE_FILE_NAME:: /dev/shmem/tracebuffer
            TRACE_DATE:: Fri Jun  8 13:14:40 2001
       TRACE_VER_MAJOR:: 0
       TRACE_VER_MINOR:: 96
   TRACE_LITTLE_ENDIAN:: TRUE
        TRACE_ENCODING:: 16 byte events
       TRACE_BOOT_DATE:: Fri Jun  8 04:31:05 2001
  TRACE_CYCLES_PER_SEC:: 400181900
         TRACE_CPU_NUM:: 4
         TRACE_SYSNAME:: QNX
        TRACE_NODENAME:: x86quad.gp.qa
     TRACE_SYS_RELEASE:: 6.1.0
     TRACE_SYS_VERSION:: 2001/06/04-14:07:56
         TRACE_MACHINE:: x86pc
     TRACE_SYSPAGE_LEN:: 2440
 -- KERNEL EVENTS --
t:0x1310da15 CPU:01 CONTROL :TIME msb:0x0000000f, lsb(offset):0x1310d81c
t:0x1310e89d CPU:01 PROCESS :PROCCREATE_NAME
                      ppid:0
                       pid:1
                      name:./procnto-smp-instr
t:0x1310eee4 CPU:00 THREAD  :THCREATE      pid:1 tid:1
t:0x1310f052 CPU:00 THREAD  :THRUNNING     pid:1 tid:1
t:0x1310f144 CPU:01 THREAD  :THCREATE      pid:1 tid:2
t:0x1310f201 CPU:01 THREAD  :THREADY       pid:1 tid:2
t:0x1310f32f CPU:02 THREAD  :THCREATE      pid:1 tid:3
t:0x1310f3ec CPU:02 THREAD  :THREADY       pid:1 tid:3
t:0x1310f52d CPU:03 THREAD  :THCREATE      pid:1 tid:4
t:0x1310f5ea CPU:03 THREAD  :THRUNNING     pid:1 tid:4
t:0x1310f731 CPU:02 THREAD  :THCREATE      pid:1 tid:5
.
.
.

To help you fine-tune your interpretation of the event data stream, we provide a library (traceparser) so you can write your own custom event interpreters.