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Filename : graphs.stp
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#!/usr/bin/stap

# ------------------------------------------------------------------------
# data collection

# disk I/O stats
probe begin { qnames["ioblock"] ++; qsq_start ("ioblock") }
probe ioblock.request { qs_wait ("ioblock") qs_run("ioblock") }
probe ioblock.end { qs_done ("ioblock") }

# CPU utilization
probe begin { qnames["cpu"] ++; qsq_start ("cpu") }
probe scheduler.cpu_on { if (!idle) {qs_wait ("cpu") qs_run ("cpu") }}
probe scheduler.cpu_off { if (!idle) qs_done ("cpu") }


# ------------------------------------------------------------------------
# utilization history tracking

global N
probe begin { N = 50 }

global qnames, util, histidx

function qsq_util_reset(q) {
  u=qsq_utilization (q, 100)
  qsq_start (q)
  return u
}

probe timer.ms(100) {  # collect utilization percentages frequently
  histidx = (histidx + 1) % N  # into circular buffer
  foreach (q in qnames)
    util[histidx,q] = qsq_util_reset(q)
}


# ------------------------------------------------------------------------
# general gnuplot graphical report generation

probe timer.ms(1000) {
  # emit gnuplot command to display recent history

  printf ("set yrange [0:100]\n")
  printf ("plot ")
  foreach (q in qnames+)
    {
      if (++nq >= 2) printf (", ")
      printf ("'-' title \"%s\" with lines", q)
    }
  printf ("\n")

  foreach (q in qnames+) {
    for (i = (histidx + 1) % N; i != histidx; i = (i + 1) % N)
      printf("%d\n", util[i,q])
    printf ("e\n")
  }

  printf ("pause 1\n")
}