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)