src/seastar/debug/task-latency.stap


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#!/usr/bin/stap

# usage: task_latency.stap process_name latency_threshold_ms

global start_time

probe process(@1).mark("reactor_run_tasks_single_start") {
    start_time[tid()] = gettimeofday_us()
}

probe process(@1).mark("reactor_run_tasks_single_end") {
    delete start_time[tid()]
}

probe timer.profile {
    if ([tid()] in start_time) {
        now = gettimeofday_us()
        start = start_time[tid()]
        if ((now - start) > $2 * 1000) {
            printf("detected tasks running for >%sms\n", @2)
            print_usyms(ubacktrace())
	}
    }
}