http://sourceware.org/systemtap/examples/subsystem-index.html Graphing Disk and CPU Utilization - http://sourceware.org/systemtap/examples/general/graphs.stp This section describes how you can graph disk and CPU utilization in real-time, i.e. in samples of 1 second each. #! stap # 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") } outputs raw statistics on both CPU and disk usage per second. I/O usage is tracked through the events ioblock.request and ioblock.request.end, which track each request (and request completion) for a generic block I/O. CPU usage is tracked through scheduler.cpu_on and scheduler.cpu_off, which are activated whenever a process begins (and ends) a command execution on a CPU.

Running by itself hardly presents any data that is useful, as in . [...] 62 5 3 4 6 4 4 5 5 3 6 5 e pause 1 However, refining the output of through gnuplot presents us with a more useful result. gnuplot is a lightweight, command-line driven plotting program that helps you display data in a graphical format. By piping output to gnuplot (as in stap disk-usage-gr http://sourceware.org/systemtap/examples/subsystem-index.html Graphing Disk and CPU Utilization - http://sourceware.org/systemtap/examples/general/graphs.stp aph.stp | gnuplot), we get a graphical output similar to the following:

Sample output Sample output of when piped through gnuplot

presents a cleaner, more useful graphical output. This graph can show you the level of utilization for both I/O and CPU, in real time. question: does this script also capture stap process? i.e. does the graph also include CPU utilization by systemtap while the script is running?