cswmon.stp

#!/usr/bin/env stap
#
######################################## 
# sudo stap cswmon.stp 5

global csw_count
global idle_count

probe scheduler.cpu_off {
    csw_count[task_prev, task_next]++
    idle_count+=idle
}

function fmt_task(task_prev, task_next) {
    return sprintf("%s(%d)->%s(%d)",
        task_execname(task_prev),
        task_pid(task_prev),
        task_execname(task_next),
        task_pid(task_next))
}

function print_cswtop () {
    printf ("%45s %10s\n", "Context switch", "COUNT")
    foreach ([task_prev, task_next] in csw_count- limit 20) {
        printf("%45s %10d\n", fmt_task(task_prev, task_next),
            csw_count[task_prev, task_next])
    }

    printf("%45s %10d\n", "idle", idle_count)
    delete csw_count
    delete idle_count
}

probe timer.s($1) {
    print_cswtop ()
    printf("————————————————————–\n")
}