NAME

       jitterdebugger - measures wake up latencies

SYNOPSIS

       jitterdebugger [OPTIONS]

DESCRIPTION

       jitterdebugger  measures  wake  up latencies. jitterdebugger starts a thread on each CPU which programs a
       timer and measures the time it takes from the timer expiring until the thread which set  the  timer  runs
       again.

       jitterdebugger default settings will produce a correct meassurement.

       The  program  runs until CTRL-C or SIGTERM is received. The results are printed to STDOUT as JSON encoded
       string.

OPTIONS

       -h, --help
              Show help text and exit.

       -v, --verbose
              Show live updates of the measurments

       -f, --file=FILE
              Write the results into the FILE

       -c, --command=CMD
              Start workload CMD in background, e.g. -c "while true; do; hackbench; done". The CMD  is  executed
              in  a  full  shell,  that  means  VARIABLE expansion works as well. When jitterdebugger terminates
              itself (because of break value or loops), the background workload is also terminated.

       -N SERVER:PORT
              Send samples to SERVER:PORT as UDP packets. See also jittersamples --listen.

       -t, --timeout=N
              Run meassurments for N seconds. N is allowed to be postfix  with  'd'  (days),  'h'  (hours),  'm'
              (minutes) or 's' seconds.

       -l, --loops=N
              Run meassurments N times and the terminate jitterdebugger.

       -b, --break=N
              Run jitterdebugger until the N or greater latency has been observed. jitterdebugger will also stop
              a  running  tracer  by  writing  0  to tracing/tracing_on. Furthermore, the value observed will be
              written to the trace buffers tracing/trace_marker, e.g "Hit latency 249".

       -i, --interval=N
              Set the sleep time between each measuring. The default value is 1000us

       -o, --output=DIR
              Write all samples measured into directory DIR. The file is called samples.raw  and  it  is  binary
              encoded and can be decoded using jittersamples. Additional meta data is stored into DIR.

       -a, --affinity=CPUSET
              Set  the CPU affinity mask. jitterdebugger starts only meassuring threads on CPUSET,. e.g. 0,2,5-7
              starts a thread on first, third and 5, 6 and 7 CPU.  May also be  set  in  hexadecimal  with  '0x'
              prefix

       -p, --priority=PRI
              Set  the  priority  of  the  meassuring  threads. The default value is 98. Note priority 99 is not
              available because 99 should only be used for kernel housekeeping tasks.

EXAMPLES

       # jitterdebugger  -v
       affinity: 0,1 = 2 [0x3]
       T: 0 (  614) A: 0 C:     13476 Min:         3 Avg:    3.08 Max:        10
       T: 1 (  615) A: 1 C:     13513 Min:         3 Avg:    3.10 Max:        20
       ^C
       {
         "cpu": {
           "0": {
             "histogram": {
               "3": 4070,
               "4": 269,
               "5": 26,
               "6": 5,
               "7": 1,
               "8": 1,
               "9": 2,
               "10": 1
             },
             "count": 4375,
             "min": 3,
             "max": 10,
             "avg": 3.08
           },
           "1": {
             "histogram": {
               "3": 4002,
               "4": 320,
               "5": 22,
               "6": 4,
               "7": 2,
               "8": 1,
               "10": 2,
               "11": 1,
               "16": 2,
               "20": 1
             },
             "count": 4357,
             "min": 3,
             "max": 20,
             "avg": 3.10
           }
         }
       }

SEE ALSO

       jittersamples(1) jitterplot(1)

                                                                                               JITTERDEBUGGER(1)