KVM: x86: Ignore MSR_AMD64_TW_CFG access

[thirdparty/kernel/stable.git] / tools / tracing / rtla / src / timerlat_aa.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2023 Red Hat Inc, Daniel Bristot de Oliveira <bristot@kernel.org>
 */

#include <stdlib.h>
#include <errno.h>
#include "utils.h"
#include "osnoise.h"
#include "timerlat.h"
#include <unistd.h>

enum timelat_state {
        TIMERLAT_INIT = 0,
        TIMERLAT_WAITING_IRQ,
        TIMERLAT_WAITING_THREAD,
};

#define MAX_COMM                24

/*
 * Per-cpu data statistics and data.
 */
struct timerlat_aa_data {
        /* Current CPU state */
        int                     curr_state;

        /* timerlat IRQ latency */
        unsigned long long      tlat_irq_seqnum;
        unsigned long long      tlat_irq_latency;
        unsigned long long      tlat_irq_timstamp;

        /* timerlat Thread latency */
        unsigned long long      tlat_thread_seqnum;
        unsigned long long      tlat_thread_latency;
        unsigned long long      tlat_thread_timstamp;

        /*
         * Information about the thread running when the IRQ
         * arrived.
         *
         * This can be blocking or interference, depending on the
         * priority of the thread. Assuming timerlat is the highest
         * prio, it is blocking. If timerlat has a lower prio, it is
         * interference.
         * note: "unsigned long long" because they are fetch using tep_get_field_val();
         */
        unsigned long long      run_thread_pid;
        char                    run_thread_comm[MAX_COMM];
        unsigned long long      thread_blocking_duration;
        unsigned long long      max_exit_idle_latency;

        /* Information about the timerlat timer irq */
        unsigned long long      timer_irq_start_time;
        unsigned long long      timer_irq_start_delay;
        unsigned long long      timer_irq_duration;
        unsigned long long      timer_exit_from_idle;

        /*
         * Information about the last IRQ before the timerlat irq
         * arrived.
         *
         * If now - timestamp is <= latency, it might have influenced
         * in the timerlat irq latency. Otherwise, ignore it.
         */
        unsigned long long      prev_irq_duration;
        unsigned long long      prev_irq_timstamp;

        /*
         * Interference sum.
         */
        unsigned long long      thread_nmi_sum;
        unsigned long long      thread_irq_sum;
        unsigned long long      thread_softirq_sum;
        unsigned long long      thread_thread_sum;

        /*
         * Interference task information.
         */
        struct trace_seq        *prev_irqs_seq;
        struct trace_seq        *nmi_seq;
        struct trace_seq        *irqs_seq;
        struct trace_seq        *softirqs_seq;
        struct trace_seq        *threads_seq;
        struct trace_seq        *stack_seq;

        /*
         * Current thread.
         */
        char                    current_comm[MAX_COMM];
        unsigned long long      current_pid;

        /*
         * Is the system running a kworker?
         */
        unsigned long long      kworker;
        unsigned long long      kworker_func;
};

/*
 * The analysis context and system wide view
 */
struct timerlat_aa_context {
        int nr_cpus;
        int dump_tasks;

        /* per CPU data */
        struct timerlat_aa_data *taa_data;

        /*
         * required to translate function names and register
         * events.
         */
        struct osnoise_tool *tool;
};

/*
 * The data is stored as a local variable, but accessed via a helper function.
 *
 * It could be stored inside the trace context. But every access would
 * require container_of() + a series of pointers. Do we need it? Not sure.
 *
 * For now keep it simple. If needed, store it in the tool, add the *context
 * as a parameter in timerlat_aa_get_ctx() and do the magic there.
 */
static struct timerlat_aa_context *__timerlat_aa_ctx;

static struct timerlat_aa_context *timerlat_aa_get_ctx(void)
{
        return __timerlat_aa_ctx;
}

/*
 * timerlat_aa_get_data - Get the per-cpu data from the timerlat context
 */
static struct timerlat_aa_data
*timerlat_aa_get_data(struct timerlat_aa_context *taa_ctx, int cpu)
{
        return &taa_ctx->taa_data[cpu];
}

/*
 * timerlat_aa_irq_latency - Handles timerlat IRQ event
 */
static int timerlat_aa_irq_latency(struct timerlat_aa_data *taa_data,
                                   struct trace_seq *s, struct tep_record *record,
                                   struct tep_event *event)
{
        /*
         * For interference, we start now looking for things that can delay
         * the thread.
         */
        taa_data->curr_state = TIMERLAT_WAITING_THREAD;
        taa_data->tlat_irq_timstamp = record->ts;

        /*
         * Zero values.
         */
        taa_data->thread_nmi_sum = 0;
        taa_data->thread_irq_sum = 0;
        taa_data->thread_softirq_sum = 0;
        taa_data->thread_blocking_duration = 0;
        taa_data->timer_irq_start_time = 0;
        taa_data->timer_irq_duration = 0;
        taa_data->timer_exit_from_idle = 0;

        /*
         * Zero interference tasks.
         */
        trace_seq_reset(taa_data->nmi_seq);
        trace_seq_reset(taa_data->irqs_seq);
        trace_seq_reset(taa_data->softirqs_seq);
        trace_seq_reset(taa_data->threads_seq);

        /* IRQ latency values */
        tep_get_field_val(s, event, "timer_latency", record, &taa_data->tlat_irq_latency, 1);
        tep_get_field_val(s, event, "seqnum", record, &taa_data->tlat_irq_seqnum, 1);

        /* The thread that can cause blocking */
        tep_get_common_field_val(s, event, "common_pid", record, &taa_data->run_thread_pid, 1);

        /*
         * Get exit from idle case.
         *
         * If it is not idle thread:
         */
        if (taa_data->run_thread_pid)
                return 0;

        /*
         * if the latency is shorter than the known exit from idle:
         */
        if (taa_data->tlat_irq_latency < taa_data->max_exit_idle_latency)
                return 0;

        /*
         * To be safe, ignore the cases in which an IRQ/NMI could have
         * interfered with the timerlat IRQ.
         */
        if (taa_data->tlat_irq_timstamp - taa_data->tlat_irq_latency
            < taa_data->prev_irq_timstamp + taa_data->prev_irq_duration)
                return 0;

        taa_data->max_exit_idle_latency = taa_data->tlat_irq_latency;

        return 0;
}

/*
 * timerlat_aa_thread_latency - Handles timerlat thread event
 */
static int timerlat_aa_thread_latency(struct timerlat_aa_data *taa_data,
                                      struct trace_seq *s, struct tep_record *record,
                                      struct tep_event *event)
{
        /*
         * For interference, we start now looking for things that can delay
         * the IRQ of the next cycle.
         */
        taa_data->curr_state = TIMERLAT_WAITING_IRQ;
        taa_data->tlat_thread_timstamp = record->ts;

        /* Thread latency values */
        tep_get_field_val(s, event, "timer_latency", record, &taa_data->tlat_thread_latency, 1);
        tep_get_field_val(s, event, "seqnum", record, &taa_data->tlat_thread_seqnum, 1);

        return 0;
}

/*
 * timerlat_aa_handler - Handle timerlat events
 *
 * This function is called to handle timerlat events recording statistics.
 *
 * Returns 0 on success, -1 otherwise.
 */
static int timerlat_aa_handler(struct trace_seq *s, struct tep_record *record,
                        struct tep_event *event, void *context)
{
        struct timerlat_aa_context *taa_ctx = timerlat_aa_get_ctx();
        struct timerlat_aa_data *taa_data = timerlat_aa_get_data(taa_ctx, record->cpu);
        unsigned long long thread;

        if (!taa_data)
                return -1;

        tep_get_field_val(s, event, "context", record, &thread, 1);
        if (!thread)
                return timerlat_aa_irq_latency(taa_data, s, record, event);
        else
                return timerlat_aa_thread_latency(taa_data, s, record, event);
}

/*
 * timerlat_aa_nmi_handler - Handles NMI noise
 *
 * It is used to collect information about interferences from NMI. It is
 * hooked to the osnoise:nmi_noise event.
 */
static int timerlat_aa_nmi_handler(struct trace_seq *s, struct tep_record *record,
                                   struct tep_event *event, void *context)
{
        struct timerlat_aa_context *taa_ctx = timerlat_aa_get_ctx();
        struct timerlat_aa_data *taa_data = timerlat_aa_get_data(taa_ctx, record->cpu);
        unsigned long long duration;
        unsigned long long start;

        tep_get_field_val(s, event, "duration", record, &duration, 1);
        tep_get_field_val(s, event, "start", record, &start, 1);

        if (taa_data->curr_state == TIMERLAT_WAITING_IRQ) {
                taa_data->prev_irq_duration = duration;
                taa_data->prev_irq_timstamp = start;

                trace_seq_reset(taa_data->prev_irqs_seq);
                trace_seq_printf(taa_data->prev_irqs_seq, "\t%24s       \t\t\t%9.2f us\n",
                         "nmi", ns_to_usf(duration));
                return 0;
        }

        taa_data->thread_nmi_sum += duration;
        trace_seq_printf(taa_data->nmi_seq, "   %24s    \t\t\t%9.2f us\n",
                 "nmi", ns_to_usf(duration));

        return 0;
}

/*
 * timerlat_aa_irq_handler - Handles IRQ noise
 *
 * It is used to collect information about interferences from IRQ. It is
 * hooked to the osnoise:irq_noise event.
 *
 * It is a little bit more complex than the other because it measures:
 *      - The IRQs that can delay the timer IRQ before it happened.
 *      - The Timerlat IRQ handler
 *      - The IRQs that happened between the timerlat IRQ and the timerlat thread
 *        (IRQ interference).
 */
static int timerlat_aa_irq_handler(struct trace_seq *s, struct tep_record *record,
                                   struct tep_event *event, void *context)
{
        struct timerlat_aa_context *taa_ctx = timerlat_aa_get_ctx();
        struct timerlat_aa_data *taa_data = timerlat_aa_get_data(taa_ctx, record->cpu);
        unsigned long long expected_start;
        unsigned long long duration;
        unsigned long long vector;
        unsigned long long start;
        char *desc;
        int val;

        tep_get_field_val(s, event, "duration", record, &duration, 1);
        tep_get_field_val(s, event, "start", record, &start, 1);
        tep_get_field_val(s, event, "vector", record, &vector, 1);
        desc = tep_get_field_raw(s, event, "desc", record, &val, 1);

        /*
         * Before the timerlat IRQ.
         */
        if (taa_data->curr_state == TIMERLAT_WAITING_IRQ) {
                taa_data->prev_irq_duration = duration;
                taa_data->prev_irq_timstamp = start;

                trace_seq_reset(taa_data->prev_irqs_seq);
                trace_seq_printf(taa_data->prev_irqs_seq, "\t%24s:%-3llu        \t\t%9.2f us\n",
                                 desc, vector, ns_to_usf(duration));
                return 0;
        }

        /*
         * The timerlat IRQ: taa_data->timer_irq_start_time is zeroed at
         * the timerlat irq handler.
         */
        if (!taa_data->timer_irq_start_time) {
                expected_start = taa_data->tlat_irq_timstamp - taa_data->tlat_irq_latency;

                taa_data->timer_irq_start_time = start;
                taa_data->timer_irq_duration = duration;

                taa_data->timer_irq_start_delay = taa_data->timer_irq_start_time - expected_start;

                /*
                 * not exit from idle.
                 */
                if (taa_data->run_thread_pid)
                        return 0;

                if (expected_start > taa_data->prev_irq_timstamp + taa_data->prev_irq_duration)
                        taa_data->timer_exit_from_idle = taa_data->timer_irq_start_delay;

                return 0;
        }

        /*
         * IRQ interference.
         */
        taa_data->thread_irq_sum += duration;
        trace_seq_printf(taa_data->irqs_seq, "  %24s:%-3llu     \t      %9.2f us\n",
                         desc, vector, ns_to_usf(duration));

        return 0;
}

static char *softirq_name[] = { "HI", "TIMER",  "NET_TX", "NET_RX", "BLOCK",
                                "IRQ_POLL", "TASKLET", "SCHED", "HRTIMER", "RCU" };


/*
 * timerlat_aa_softirq_handler - Handles Softirq noise
 *
 * It is used to collect information about interferences from Softirq. It is
 * hooked to the osnoise:softirq_noise event.
 *
 * It is only printed in the non-rt kernel, as softirqs become thread on RT.
 */
static int timerlat_aa_softirq_handler(struct trace_seq *s, struct tep_record *record,
                                       struct tep_event *event, void *context)
{
        struct timerlat_aa_context *taa_ctx = timerlat_aa_get_ctx();
        struct timerlat_aa_data *taa_data = timerlat_aa_get_data(taa_ctx, record->cpu);
        unsigned long long duration;
        unsigned long long vector;
        unsigned long long start;

        if (taa_data->curr_state == TIMERLAT_WAITING_IRQ)
                return 0;

        tep_get_field_val(s, event, "duration", record, &duration, 1);
        tep_get_field_val(s, event, "start", record, &start, 1);
        tep_get_field_val(s, event, "vector", record, &vector, 1);

        taa_data->thread_softirq_sum += duration;

        trace_seq_printf(taa_data->softirqs_seq, "\t%24s:%-3llu \t      %9.2f us\n",
                         softirq_name[vector], vector, ns_to_usf(duration));
        return 0;
}

/*
 * timerlat_aa_softirq_handler - Handles thread noise
 *
 * It is used to collect information about interferences from threads. It is
 * hooked to the osnoise:thread_noise event.
 *
 * Note: if you see thread noise, your timerlat thread was not the highest prio one.
 */
static int timerlat_aa_thread_handler(struct trace_seq *s, struct tep_record *record,
                                      struct tep_event *event, void *context)
{
        struct timerlat_aa_context *taa_ctx = timerlat_aa_get_ctx();
        struct timerlat_aa_data *taa_data = timerlat_aa_get_data(taa_ctx, record->cpu);
        unsigned long long duration;
        unsigned long long start;
        unsigned long long pid;
        const char *comm;
        int val;

        if (taa_data->curr_state == TIMERLAT_WAITING_IRQ)
                return 0;

        tep_get_field_val(s, event, "duration", record, &duration, 1);
        tep_get_field_val(s, event, "start", record, &start, 1);

        tep_get_common_field_val(s, event, "common_pid", record, &pid, 1);
        comm = tep_get_field_raw(s, event, "comm", record, &val, 1);

        if (pid == taa_data->run_thread_pid && !taa_data->thread_blocking_duration) {
                taa_data->thread_blocking_duration = duration;

                if (comm)
                        strncpy(taa_data->run_thread_comm, comm, MAX_COMM);
                else
                        sprintf(taa_data->run_thread_comm, "<...>");

        } else {
                taa_data->thread_thread_sum += duration;

                trace_seq_printf(taa_data->threads_seq, "\t%24s:%-3llu  \t\t%9.2f us\n",
                         comm, pid, ns_to_usf(duration));
        }

        return 0;
}

/*
 * timerlat_aa_stack_handler - Handles timerlat IRQ stack trace
 *
 * Saves and parse the stack trace generated by the timerlat IRQ.
 */
static int timerlat_aa_stack_handler(struct trace_seq *s, struct tep_record *record,
                              struct tep_event *event, void *context)
{
        struct timerlat_aa_context *taa_ctx = timerlat_aa_get_ctx();
        struct timerlat_aa_data *taa_data = timerlat_aa_get_data(taa_ctx, record->cpu);
        unsigned long *caller;
        const char *function;
        int val, i;

        trace_seq_reset(taa_data->stack_seq);

        trace_seq_printf(taa_data->stack_seq, "    Blocking thread stack trace\n");
        caller = tep_get_field_raw(s, event, "caller", record, &val, 1);
        if (caller) {
                for (i = 0; ; i++) {
                        function = tep_find_function(taa_ctx->tool->trace.tep, caller[i]);
                        if (!function)
                                break;
                        trace_seq_printf(taa_data->stack_seq, "\t\t-> %s\n", function);
                }
        }
        return 0;
}

/*
 * timerlat_aa_sched_switch_handler - Tracks the current thread running on the CPU
 *
 * Handles the sched:sched_switch event to trace the current thread running on the
 * CPU. It is used to display the threads running on the other CPUs when the trace
 * stops.
 */
static int timerlat_aa_sched_switch_handler(struct trace_seq *s, struct tep_record *record,
                                            struct tep_event *event, void *context)
{
        struct timerlat_aa_context *taa_ctx = timerlat_aa_get_ctx();
        struct timerlat_aa_data *taa_data = timerlat_aa_get_data(taa_ctx, record->cpu);
        const char *comm;
        int val;

        tep_get_field_val(s, event, "next_pid", record, &taa_data->current_pid, 1);
        comm = tep_get_field_raw(s, event, "next_comm", record, &val, 1);

        strncpy(taa_data->current_comm, comm, MAX_COMM);

        /*
         * If this was a kworker, clean the last kworkers that ran.
         */
        taa_data->kworker = 0;
        taa_data->kworker_func = 0;

        return 0;
}

/*
 * timerlat_aa_kworker_start_handler - Tracks a kworker running on the CPU
 *
 * Handles workqueue:workqueue_execute_start event, keeping track of
 * the job that a kworker could be doing in the CPU.
 *
 * We already catch problems of hardware related latencies caused by work queues
 * running driver code that causes hardware stall. For example, with DRM drivers.
 */
static int timerlat_aa_kworker_start_handler(struct trace_seq *s, struct tep_record *record,
                                             struct tep_event *event, void *context)
{
        struct timerlat_aa_context *taa_ctx = timerlat_aa_get_ctx();
        struct timerlat_aa_data *taa_data = timerlat_aa_get_data(taa_ctx, record->cpu);

        tep_get_field_val(s, event, "work", record, &taa_data->kworker, 1);
        tep_get_field_val(s, event, "function", record, &taa_data->kworker_func, 1);
        return 0;
}

/*
 * timerlat_thread_analysis - Prints the analysis of a CPU that hit a stop tracing
 *
 * This is the core of the analysis.
 */
static void timerlat_thread_analysis(struct timerlat_aa_data *taa_data, int cpu,
                                     int irq_thresh, int thread_thresh)
{
        unsigned long long exp_irq_ts;
        int total;
        int irq;

        /*
         * IRQ latency or Thread latency?
         */
        if (taa_data->tlat_irq_seqnum > taa_data->tlat_thread_seqnum) {
                irq = 1;
                total = taa_data->tlat_irq_latency;
        } else {
                irq = 0;
                total = taa_data->tlat_thread_latency;
        }

        /*
         * Expected IRQ arrival time using the trace clock as the base.
         */
        exp_irq_ts = taa_data->timer_irq_start_time - taa_data->timer_irq_start_delay;

        if (exp_irq_ts < taa_data->prev_irq_timstamp + taa_data->prev_irq_duration)
                printf("  Previous IRQ interference:    \t\t up to  %9.2f us\n",
                        ns_to_usf(taa_data->prev_irq_duration));

        /*
         * The delay that the IRQ suffered before starting.
         */
        printf("  IRQ handler delay:            %16s    %9.2f us (%.2f %%)\n",
                (ns_to_usf(taa_data->timer_exit_from_idle) > 10) ? "(exit from idle)" : "",
                ns_to_usf(taa_data->timer_irq_start_delay),
                ns_to_per(total, taa_data->timer_irq_start_delay));

        /*
         * Timerlat IRQ.
         */
        printf("  IRQ latency:  \t\t\t\t        %9.2f us\n",
                ns_to_usf(taa_data->tlat_irq_latency));

        if (irq) {
                /*
                 * If the trace stopped due to IRQ, the other events will not happen
                 * because... the trace stopped :-).
                 *
                 * That is all folks, the stack trace was printed before the stop,
                 * so it will be displayed, it is the key.
                 */
                printf("  Blocking thread:\n");
                printf("        %24s:%-9llu\n",
                        taa_data->run_thread_comm, taa_data->run_thread_pid);
        } else  {
                /*
                 * The duration of the IRQ handler that handled the timerlat IRQ.
                 */
                printf("  Timerlat IRQ duration:        \t\t    %9.2f us (%.2f %%)\n",
                        ns_to_usf(taa_data->timer_irq_duration),
                        ns_to_per(total, taa_data->timer_irq_duration));

                /*
                 * The amount of time that the current thread postponed the scheduler.
                 *
                 * Recalling that it is net from NMI/IRQ/Softirq interference, so there
                 * is no need to compute values here.
                 */
                printf("  Blocking thread:      \t\t\t  %9.2f us (%.2f %%)\n",
                        ns_to_usf(taa_data->thread_blocking_duration),
                        ns_to_per(total, taa_data->thread_blocking_duration));

                printf("        %24s:%-9llu             %9.2f us\n",
                        taa_data->run_thread_comm, taa_data->run_thread_pid,
                        ns_to_usf(taa_data->thread_blocking_duration));
        }

        /*
         * Print the stack trace!
         */
        trace_seq_do_printf(taa_data->stack_seq);

        /*
         * NMIs can happen during the IRQ, so they are always possible.
         */
        if (taa_data->thread_nmi_sum)
                printf("  NMI interference      \t\t\t  %9.2f us (%.2f %%)\n",
                        ns_to_usf(taa_data->thread_nmi_sum),
                        ns_to_per(total, taa_data->thread_nmi_sum));

        /*
         * If it is an IRQ latency, the other factors can be skipped.
         */
        if (irq)
                goto print_total;

        /*
         * Prints the interference caused by IRQs to the thread latency.
         */
        if (taa_data->thread_irq_sum) {
                printf("  IRQ interference      \t\t\t  %9.2f us (%.2f %%)\n",
                        ns_to_usf(taa_data->thread_irq_sum),
                        ns_to_per(total, taa_data->thread_irq_sum));

                trace_seq_do_printf(taa_data->irqs_seq);
        }

        /*
         * Prints the interference caused by Softirqs to the thread latency.
         */
        if (taa_data->thread_softirq_sum) {
                printf("  Softirq interference  \t\t\t  %9.2f us (%.2f %%)\n",
                        ns_to_usf(taa_data->thread_softirq_sum),
                        ns_to_per(total, taa_data->thread_softirq_sum));

                trace_seq_do_printf(taa_data->softirqs_seq);
        }

        /*
         * Prints the interference caused by other threads to the thread latency.
         *
         * If this happens, your timerlat is not the highest prio. OK, migration
         * thread can happen. But otherwise, you are not measuring the "scheduling
         * latency" only, and here is the difference from scheduling latency and
         * timer handling latency.
         */
        if (taa_data->thread_thread_sum) {
                printf("  Thread interference   \t\t\t  %9.2f us (%.2f %%)\n",
                        ns_to_usf(taa_data->thread_thread_sum),
                        ns_to_per(total, taa_data->thread_thread_sum));

                trace_seq_do_printf(taa_data->threads_seq);
        }

        /*
         * Done.
         */
print_total:
        printf("------------------------------------------------------------------------\n");
        printf("  %s latency:   \t\t\t  %9.2f us (100%%)\n", irq ? "IRQ" : "Thread",
                ns_to_usf(total));
}

static int timerlat_auto_analysis_collect_trace(struct timerlat_aa_context *taa_ctx)
{
        struct trace_instance *trace = &taa_ctx->tool->trace;
        int retval;

        retval = tracefs_iterate_raw_events(trace->tep,
                                            trace->inst,
                                            NULL,
                                            0,
                                            collect_registered_events,
                                            trace);
                if (retval < 0) {
                        err_msg("Error iterating on events\n");
                        return 0;
                }

        return 1;
}

/**
 * timerlat_auto_analysis - Analyze the collected data
 */
void timerlat_auto_analysis(int irq_thresh, int thread_thresh)
{
        struct timerlat_aa_context *taa_ctx = timerlat_aa_get_ctx();
        unsigned long long max_exit_from_idle = 0;
        struct timerlat_aa_data *taa_data;
        int max_exit_from_idle_cpu;
        struct tep_handle *tep;
        int cpu;

        timerlat_auto_analysis_collect_trace(taa_ctx);

        /* bring stop tracing to the ns scale */
        irq_thresh = irq_thresh * 1000;
        thread_thresh = thread_thresh * 1000;

        for (cpu = 0; cpu < taa_ctx->nr_cpus; cpu++) {
                taa_data = timerlat_aa_get_data(taa_ctx, cpu);

                if (irq_thresh && taa_data->tlat_irq_latency >= irq_thresh) {
                        printf("## CPU %d hit stop tracing, analyzing it ##\n", cpu);
                        timerlat_thread_analysis(taa_data, cpu, irq_thresh, thread_thresh);
                } else if (thread_thresh && (taa_data->tlat_thread_latency) >= thread_thresh) {
                        printf("## CPU %d hit stop tracing, analyzing it ##\n", cpu);
                        timerlat_thread_analysis(taa_data, cpu, irq_thresh, thread_thresh);
                }

                if (taa_data->max_exit_idle_latency > max_exit_from_idle) {
                        max_exit_from_idle = taa_data->max_exit_idle_latency;
                        max_exit_from_idle_cpu = cpu;
                }

        }

        if (max_exit_from_idle) {
                printf("\n");
                printf("Max timerlat IRQ latency from idle: %.2f us in cpu %d\n",
                        ns_to_usf(max_exit_from_idle), max_exit_from_idle_cpu);
        }
        if (!taa_ctx->dump_tasks)
                return;

        printf("\n");
        printf("Printing CPU tasks:\n");
        for (cpu = 0; cpu < taa_ctx->nr_cpus; cpu++) {
                taa_data = timerlat_aa_get_data(taa_ctx, cpu);
                tep = taa_ctx->tool->trace.tep;

                printf("    [%.3d] %24s:%llu", cpu, taa_data->current_comm, taa_data->current_pid);

                if (taa_data->kworker_func)
                        printf(" kworker:%s:%s",
                                tep_find_function(tep, taa_data->kworker) ? : "<...>",
                                tep_find_function(tep, taa_data->kworker_func));
                printf("\n");
        }

}

/*
 * timerlat_aa_destroy_seqs - Destroy seq files used to store parsed data
 */
static void timerlat_aa_destroy_seqs(struct timerlat_aa_context *taa_ctx)
{
        struct timerlat_aa_data *taa_data;
        int i;

        if (!taa_ctx->taa_data)
                return;

        for (i = 0; i < taa_ctx->nr_cpus; i++) {
                taa_data = timerlat_aa_get_data(taa_ctx, i);

                if (taa_data->prev_irqs_seq) {
                        trace_seq_destroy(taa_data->prev_irqs_seq);
                        free(taa_data->prev_irqs_seq);
                }

                if (taa_data->nmi_seq) {
                        trace_seq_destroy(taa_data->nmi_seq);
                        free(taa_data->nmi_seq);
                }

                if (taa_data->irqs_seq) {
                        trace_seq_destroy(taa_data->irqs_seq);
                        free(taa_data->irqs_seq);
                }

                if (taa_data->softirqs_seq) {
                        trace_seq_destroy(taa_data->softirqs_seq);
                        free(taa_data->softirqs_seq);
                }

                if (taa_data->threads_seq) {
                        trace_seq_destroy(taa_data->threads_seq);
                        free(taa_data->threads_seq);
                }

                if (taa_data->stack_seq) {
                        trace_seq_destroy(taa_data->stack_seq);
                        free(taa_data->stack_seq);
                }
        }
}

/*
 * timerlat_aa_init_seqs - Init seq files used to store parsed information
 *
 * Instead of keeping data structures to store raw data, use seq files to
 * store parsed data.
 *
 * Allocates and initialize seq files.
 *
 * Returns 0 on success, -1 otherwise.
 */
static int timerlat_aa_init_seqs(struct timerlat_aa_context *taa_ctx)
{
        struct timerlat_aa_data *taa_data;
        int i;

        for (i = 0; i < taa_ctx->nr_cpus; i++) {

                taa_data = timerlat_aa_get_data(taa_ctx, i);

                taa_data->prev_irqs_seq = calloc(1, sizeof(*taa_data->prev_irqs_seq));
                if (!taa_data->prev_irqs_seq)
                        goto out_err;

                trace_seq_init(taa_data->prev_irqs_seq);

                taa_data->nmi_seq = calloc(1, sizeof(*taa_data->nmi_seq));
                if (!taa_data->nmi_seq)
                        goto out_err;

                trace_seq_init(taa_data->nmi_seq);

                taa_data->irqs_seq = calloc(1, sizeof(*taa_data->irqs_seq));
                if (!taa_data->irqs_seq)
                        goto out_err;

                trace_seq_init(taa_data->irqs_seq);

                taa_data->softirqs_seq = calloc(1, sizeof(*taa_data->softirqs_seq));
                if (!taa_data->softirqs_seq)
                        goto out_err;

                trace_seq_init(taa_data->softirqs_seq);

                taa_data->threads_seq = calloc(1, sizeof(*taa_data->threads_seq));
                if (!taa_data->threads_seq)
                        goto out_err;

                trace_seq_init(taa_data->threads_seq);

                taa_data->stack_seq = calloc(1, sizeof(*taa_data->stack_seq));
                if (!taa_data->stack_seq)
                        goto out_err;

                trace_seq_init(taa_data->stack_seq);
        }

        return 0;

out_err:
        timerlat_aa_destroy_seqs(taa_ctx);
        return -1;
}

/*
 * timerlat_aa_unregister_events - Unregister events used in the auto-analysis
 */
static void timerlat_aa_unregister_events(struct osnoise_tool *tool, int dump_tasks)
{

        tep_unregister_event_handler(tool->trace.tep, -1, "ftrace", "timerlat",
                                     timerlat_aa_handler, tool);

        tracefs_event_disable(tool->trace.inst, "osnoise", NULL);

        tep_unregister_event_handler(tool->trace.tep, -1, "osnoise", "nmi_noise",
                                     timerlat_aa_nmi_handler, tool);

        tep_unregister_event_handler(tool->trace.tep, -1, "osnoise", "irq_noise",
                                     timerlat_aa_irq_handler, tool);

        tep_unregister_event_handler(tool->trace.tep, -1, "osnoise", "softirq_noise",
                                     timerlat_aa_softirq_handler, tool);

        tep_unregister_event_handler(tool->trace.tep, -1, "osnoise", "thread_noise",
                                     timerlat_aa_thread_handler, tool);

        tep_unregister_event_handler(tool->trace.tep, -1, "ftrace", "kernel_stack",
                                     timerlat_aa_stack_handler, tool);
        if (!dump_tasks)
                return;

        tracefs_event_disable(tool->trace.inst, "sched", "sched_switch");
        tep_unregister_event_handler(tool->trace.tep, -1, "sched", "sched_switch",
                                     timerlat_aa_sched_switch_handler, tool);

        tracefs_event_disable(tool->trace.inst, "workqueue", "workqueue_execute_start");
        tep_unregister_event_handler(tool->trace.tep, -1, "workqueue", "workqueue_execute_start",
                                     timerlat_aa_kworker_start_handler, tool);
}

/*
 * timerlat_aa_register_events - Register events used in the auto-analysis
 *
 * Returns 0 on success, -1 otherwise.
 */
static int timerlat_aa_register_events(struct osnoise_tool *tool, int dump_tasks)
{
        int retval;

        tep_register_event_handler(tool->trace.tep, -1, "ftrace", "timerlat",
                                timerlat_aa_handler, tool);


        /*
         * register auto-analysis handlers.
         */
        retval = tracefs_event_enable(tool->trace.inst, "osnoise", NULL);
        if (retval < 0 && !errno) {
                err_msg("Could not find osnoise events\n");
                goto out_err;
        }

        tep_register_event_handler(tool->trace.tep, -1, "osnoise", "nmi_noise",
                                   timerlat_aa_nmi_handler, tool);

        tep_register_event_handler(tool->trace.tep, -1, "osnoise", "irq_noise",
                                   timerlat_aa_irq_handler, tool);

        tep_register_event_handler(tool->trace.tep, -1, "osnoise", "softirq_noise",
                                   timerlat_aa_softirq_handler, tool);

        tep_register_event_handler(tool->trace.tep, -1, "osnoise", "thread_noise",
                                   timerlat_aa_thread_handler, tool);

        tep_register_event_handler(tool->trace.tep, -1, "ftrace", "kernel_stack",
                                   timerlat_aa_stack_handler, tool);

        if (!dump_tasks)
                return 0;

        /*
         * Dump task events.
         */
        retval = tracefs_event_enable(tool->trace.inst, "sched", "sched_switch");
        if (retval < 0 && !errno) {
                err_msg("Could not find sched_switch\n");
                goto out_err;
        }

        tep_register_event_handler(tool->trace.tep, -1, "sched", "sched_switch",
                                   timerlat_aa_sched_switch_handler, tool);

        retval = tracefs_event_enable(tool->trace.inst, "workqueue", "workqueue_execute_start");
        if (retval < 0 && !errno) {
                err_msg("Could not find workqueue_execute_start\n");
                goto out_err;
        }

        tep_register_event_handler(tool->trace.tep, -1, "workqueue", "workqueue_execute_start",
                                   timerlat_aa_kworker_start_handler, tool);

        return 0;

out_err:
        timerlat_aa_unregister_events(tool, dump_tasks);
        return -1;
}

/**
 * timerlat_aa_destroy - Destroy timerlat auto-analysis
 */
void timerlat_aa_destroy(void)
{
        struct timerlat_aa_context *taa_ctx = timerlat_aa_get_ctx();

        if (!taa_ctx)
                return;

        if (!taa_ctx->taa_data)
                goto out_ctx;

        timerlat_aa_unregister_events(taa_ctx->tool, taa_ctx->dump_tasks);
        timerlat_aa_destroy_seqs(taa_ctx);
        free(taa_ctx->taa_data);
out_ctx:
        free(taa_ctx);
}

/**
 * timerlat_aa_init - Initialize timerlat auto-analysis
 *
 * Returns 0 on success, -1 otherwise.
 */
int timerlat_aa_init(struct osnoise_tool *tool, int dump_tasks)
{
        int nr_cpus = sysconf(_SC_NPROCESSORS_CONF);
        struct timerlat_aa_context *taa_ctx;
        int retval;

        taa_ctx = calloc(1, sizeof(*taa_ctx));
        if (!taa_ctx)
                return -1;

        __timerlat_aa_ctx = taa_ctx;

        taa_ctx->nr_cpus = nr_cpus;
        taa_ctx->tool = tool;
        taa_ctx->dump_tasks = dump_tasks;

        taa_ctx->taa_data = calloc(nr_cpus, sizeof(*taa_ctx->taa_data));
        if (!taa_ctx->taa_data)
                goto out_err;

        retval = timerlat_aa_init_seqs(taa_ctx);
        if (retval)
                goto out_err;

        retval = timerlat_aa_register_events(tool, dump_tasks);
        if (retval)
                goto out_err;

        return 0;

out_err:
        timerlat_aa_destroy();
        return -1;
}