/usr/share/systemtap/examples/process
Edit: /usr/share/systemtap/examples/process/cycle_thief.stp (2893B)
#!/usr/bin/stap
# Copyright (C) 2010-2016 Red Hat, Inc.
# Write by William Cohen
#
# cycle_thief provide the following information for the specified pid:
# Number of times the task is migrated to another cpu
# How long the task is scheduled on and off a processor
# Tasks that run when the task is scheduled off the processor
# IRQs that run when the task is scheduled on the processor
#
# Run the script with:
# stap cycle_thief.stp -x pid
#
# control-c to exit data collection
global last_cpu = -1
global pid_on, pid_off, migrated
global time_on, time_off, irq_entry
global cycle_thief, irq_thief, cycle_thief_name
probe kernel.trace("sched_switch") {
t = gettimeofday_us(); c = cpu();
if ($prev->pid == target() && $next->pid != target()) {
/* being switched out */
pid_off = t; last_cpu = c;
if (pid_on) time_on <<< pid_off - pid_on;
} else if ($prev->pid != target() && $next->pid == target()) {
/* being switched in */
pid_on = t;
if (pid_off) time_off <<< pid_on - pid_off;
if (c != last_cpu) ++migrated;
}
/* watch what other processes scheduled while pid off */
if (pid_off > pid_on && c == last_cpu) {
cycle_thief[$next->pid] <<< 1;
cycle_thief_name[$next->pid] = kernel_string($next->comm)
}
}
/* what interrupts occur while process is running */
probe kernel.{trace("irq_handler_entry")!, trace("irq_entry")}
{
t = gettimeofday_us(); c = cpu();
i = @defined($irq) ? $irq : $id;
/* watch what irq run while pid is running */
if (pid_on > pid_off && c == last_cpu) {
irq_entry[i] = t;
}
}
probe kernel.{trace("irq_handler_exit")!, trace("irq_exit")}
{
i = @defined($irq) ? $irq : $id;
t = gettimeofday_us(); c = cpu(); irqt=irq_entry[i]
/* watch what irq run while pid is running */
if (pid_on > pid_off && c == last_cpu && irqt) {
irq_thief[i] <<< t - irqt;
delete irq_entry[i];
}
}
probe end {
printf("\n")
printf("task %d migrated: %d\n", target(), migrated)
if (@count(time_on)) {
printf("\n")
printf("task %d on processor (us):\n", target())
print(@hist_log(time_on));
}
if (@count(time_off)) {
printf("\n")
printf("task %d off processor (us)\n", target())
print(@hist_log(time_off));
}
printf("\n")
printf("other pids taking processor from task %d\n", target())
printf("%6s %10s %s\n", "PID", "count", "command");
foreach (p in cycle_thief-)
printf("%6d %10d %s\n", p, @count(cycle_thief[p]), cycle_thief_name[p])
printf("\n")
printf("irq taking processor from task %d\n", target())
printf("%6s %10s %10s %10s %10s %10s\n", "irq", "count",
"min(us)", "avg(us)", "max(us)", "variance(us^2)")
foreach (p in irq_thief-)
printf("%6d %10d %10d %10d %10d %10d\n", p, @count(irq_thief[p]),
@min(irq_thief[p]), @avg(irq_thief[p]), @max(irq_thief[p]),
@variance(irq_thief[p]))
}