[V9,07/14] rtla/timerlat: Add timerlat hist mode

diff --git a/tools/tracing/rtla/src/timerlat.c b/tools/tracing/rtla/src/timerlat.c
index 29a51c01b084..97abbf494fee 100644
--- a/tools/tracing/rtla/src/timerlat.c
+++ b/tools/tracing/rtla/src/timerlat.c
@@ -25,7 +25,8 @@  static void timerlat_usage(void)
 		"  usage: [rtla] timerlat [MODE] ...",
 		"",
 		"  modes:",
-		"     top  - prints the summary from timerlat tracer",
+		"     top   - prints the summary from timerlat tracer",
+		"     hist  - prints a histogram of timer latencies",
 		"",
 		"if no MODE is given, the top mode is called, passing the arguments",
 		NULL,
@@ -60,6 +61,9 @@  int timerlat_main(int argc, char *argv[])
 	} else if (strcmp(argv[1], "top") == 0) {
 		timerlat_top_main(argc-1, &argv[1]);
 		exit(0);
+	} else if (strcmp(argv[1], "hist") == 0) {
+		timerlat_hist_main(argc-1, &argv[1]);
+		exit(0);
 	}
 
 usage:
diff --git a/tools/tracing/rtla/src/timerlat.h b/tools/tracing/rtla/src/timerlat.h
index 6f9d3925acd0..88561bfd14f3 100644
--- a/tools/tracing/rtla/src/timerlat.h
+++ b/tools/tracing/rtla/src/timerlat.h
@@ -1,4 +1,4 @@ 
 // SPDX-License-Identifier: GPL-2.0
-
+int timerlat_hist_main(int argc, char *argv[]);
 int timerlat_top_main(int argc, char *argv[]);
 int timerlat_main(int argc, char *argv[]);
diff --git a/tools/tracing/rtla/src/timerlat_hist.c b/tools/tracing/rtla/src/timerlat_hist.c
new file mode 100644
index 000000000000..235f9620ef3d
--- /dev/null
+++ b/tools/tracing/rtla/src/timerlat_hist.c
@@ -0,0 +1,822 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2021 Red Hat Inc, Daniel Bristot de Oliveira <bristot@kernel.org>
+ */
+
+#include <getopt.h>
+#include <stdlib.h>
+#include <string.h>
+#include <signal.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <time.h>
+
+#include "utils.h"
+#include "osnoise.h"
+#include "timerlat.h"
+
+struct timerlat_hist_params {
+	char			*cpus;
+	char			*monitored_cpus;
+	char			*trace_output;
+	unsigned long long	runtime;
+	long long		stop_us;
+	long long		stop_total_us;
+	long long		timerlat_period_us;
+	long long		print_stack;
+	int			sleep_time;
+	int			output_divisor;
+	int			duration;
+	int			set_sched;
+	struct sched_attr	sched_param;
+
+	char			no_irq;
+	char			no_thread;
+	char			no_header;
+	char			no_summary;
+	char			no_index;
+	char			with_zeros;
+	int			bucket_size;
+	int			entries;
+};
+
+struct timerlat_hist_cpu {
+	int			*irq;
+	int			*thread;
+
+	int			irq_count;
+	int			thread_count;
+
+	unsigned long long	min_irq;
+	unsigned long long	sum_irq;
+	unsigned long long	max_irq;
+
+	unsigned long long	min_thread;
+	unsigned long long	sum_thread;
+	unsigned long long	max_thread;
+};
+
+struct timerlat_hist_data {
+	struct timerlat_hist_cpu	*hist;
+	int				entries;
+	int				bucket_size;
+	int				nr_cpus;
+};
+
+/*
+ * timerlat_free_histogram - free runtime data
+ */
+static void
+timerlat_free_histogram(struct timerlat_hist_data *data)
+{
+	int cpu;
+
+	/* one histogram for IRQ and one for thread, per CPU */
+	for (cpu = 0; cpu < data->nr_cpus; cpu++) {
+		if (data->hist[cpu].irq)
+			free(data->hist[cpu].irq);
+
+		if (data->hist[cpu].thread)
+			free(data->hist[cpu].thread);
+	}
+
+	/* one set of histograms per CPU */
+	if (data->hist)
+		free(data->hist);
+
+	free(data);
+}
+
+/*
+ * timerlat_alloc_histogram - alloc runtime data
+ */
+static struct timerlat_hist_data
+*timerlat_alloc_histogram(int nr_cpus, int entries, int bucket_size)
+{
+	struct timerlat_hist_data *data;
+	int cpu;
+
+	data = calloc(1, sizeof(*data));
+	if (!data)
+		return NULL;
+
+	data->entries = entries;
+	data->bucket_size = bucket_size;
+	data->nr_cpus = nr_cpus;
+
+	/* one set of histograms per CPU */
+	data->hist = calloc(1, sizeof(*data->hist) * nr_cpus);
+	if (!data->hist)
+		goto cleanup;
+
+	/* one histogram for IRQ and one for thread, per cpu */
+	for (cpu = 0; cpu < nr_cpus; cpu++) {
+		data->hist[cpu].irq = calloc(1, sizeof(*data->hist->irq) * (entries + 1));
+		if (!data->hist[cpu].irq)
+			goto cleanup;
+		data->hist[cpu].thread = calloc(1, sizeof(*data->hist->thread) * (entries + 1));
+		if (!data->hist[cpu].thread)
+			goto cleanup;
+	}
+
+	/* set the min to max */
+	for (cpu = 0; cpu < nr_cpus; cpu++) {
+		data->hist[cpu].min_irq = ~0;
+		data->hist[cpu].min_thread = ~0;
+	}
+
+	return data;
+
+cleanup:
+	timerlat_free_histogram(data);
+	return NULL;
+}
+
+/*
+ * timerlat_hist_update - record a new timerlat occurent on cpu, updating data
+ */
+static void
+timerlat_hist_update(struct osnoise_tool *tool, int cpu,
+		     unsigned long long thread,
+		     unsigned long long latency)
+{
+	struct timerlat_hist_params *params = tool->params;
+	struct timerlat_hist_data *data = tool->data;
+	int entries = data->entries;
+	int bucket;
+	int *hist;
+
+	if (params->output_divisor)
+		latency = latency / params->output_divisor;
+
+	if (data->bucket_size)
+		bucket = latency / data->bucket_size;
+
+	if (!thread) {
+		hist = data->hist[cpu].irq;
+		data->hist[cpu].irq_count++;
+		update_min(&data->hist[cpu].min_irq, &latency);
+		update_sum(&data->hist[cpu].sum_irq, &latency);
+		update_max(&data->hist[cpu].max_irq, &latency);
+	} else {
+		hist = data->hist[cpu].thread;
+		data->hist[cpu].thread_count++;
+		update_min(&data->hist[cpu].min_thread, &latency);
+		update_sum(&data->hist[cpu].sum_thread, &latency);
+		update_max(&data->hist[cpu].max_thread, &latency);
+	}
+
+	if (bucket < entries)
+		hist[bucket]++;
+	else
+		hist[entries]++;
+}
+
+/*
+ * timerlat_hist_handler - this is the handler for timerlat tracer events
+ */
+static int
+timerlat_hist_handler(struct trace_seq *s, struct tep_record *record,
+		     struct tep_event *event, void *data)
+{
+	struct trace_instance *trace = data;
+	unsigned long long thread, latency;
+	struct osnoise_tool *tool;
+	int cpu = record->cpu;
+
+	tool = container_of(trace, struct osnoise_tool, trace);
+
+	tep_get_field_val(s, event, "context", record, &thread, 1);
+	tep_get_field_val(s, event, "timer_latency", record, &latency, 1);
+
+	timerlat_hist_update(tool, cpu, thread, latency);
+
+	return 0;
+}
+
+/*
+ * timerlat_hist_header - print the header of the tracer to the output
+ */
+static void timerlat_hist_header(struct osnoise_tool *tool)
+{
+	struct timerlat_hist_params *params = tool->params;
+	struct timerlat_hist_data *data = tool->data;
+	struct trace_seq *s = tool->trace.seq;
+	char duration[26];
+	int cpu;
+
+	if (params->no_header)
+		return;
+
+	get_duration(tool->start_time, duration, sizeof(duration));
+	trace_seq_printf(s, "# RTLA timerlat histogram\n");
+	trace_seq_printf(s, "# Time unit is %s (%s)\n",
+			params->output_divisor == 1 ? "nanoseconds" : "microseconds",
+			params->output_divisor == 1 ? "ns" : "us");
+
+	trace_seq_printf(s, "# Duration: %s\n", duration);
+
+	if (!params->no_index)
+		trace_seq_printf(s, "Index");
+
+	for (cpu = 0; cpu < data->nr_cpus; cpu++) {
+		if (params->cpus && !params->monitored_cpus[cpu])
+			continue;
+
+		if (!data->hist[cpu].irq_count && !data->hist[cpu].thread_count)
+			continue;
+
+		if (!params->no_irq)
+			trace_seq_printf(s, "   IRQ-%03d", cpu);
+
+		if (!params->no_thread)
+			trace_seq_printf(s, "   Thr-%03d", cpu);
+	}
+	trace_seq_printf(s, "\n");
+
+
+	trace_seq_do_printf(s);
+	trace_seq_reset(s);
+}
+
+/*
+ * timerlat_print_summary - print the summary of the hist data to the output
+ */
+static void
+timerlat_print_summary(struct timerlat_hist_params *params,
+		       struct trace_instance *trace,
+		       struct timerlat_hist_data *data)
+{
+	int cpu;
+
+	if (params->no_summary)
+		return;
+
+	if (!params->no_index)
+		trace_seq_printf(trace->seq, "count:");
+
+	for (cpu = 0; cpu < data->nr_cpus; cpu++) {
+		if (params->cpus && !params->monitored_cpus[cpu])
+			continue;
+
+		if (!data->hist[cpu].irq_count && !data->hist[cpu].thread_count)
+			continue;
+
+		if (!params->no_irq)
+			trace_seq_printf(trace->seq, "%9d ",
+					data->hist[cpu].irq_count);
+
+		if (!params->no_thread)
+			trace_seq_printf(trace->seq, "%9d ",
+					data->hist[cpu].thread_count);
+	}
+	trace_seq_printf(trace->seq, "\n");
+
+	if (!params->no_index)
+		trace_seq_printf(trace->seq, "min:  ");
+
+	for (cpu = 0; cpu < data->nr_cpus; cpu++) {
+		if (params->cpus && !params->monitored_cpus[cpu])
+			continue;
+
+		if (!data->hist[cpu].irq_count && !data->hist[cpu].thread_count)
+			continue;
+
+		if (!params->no_irq)
+			trace_seq_printf(trace->seq, "%9llu ",
+					data->hist[cpu].min_irq);
+
+		if (!params->no_thread)
+			trace_seq_printf(trace->seq, "%9llu ",
+					data->hist[cpu].min_thread);
+	}
+	trace_seq_printf(trace->seq, "\n");
+
+	if (!params->no_index)
+		trace_seq_printf(trace->seq, "avg:  ");
+
+	for (cpu = 0; cpu < data->nr_cpus; cpu++) {
+		if (params->cpus && !params->monitored_cpus[cpu])
+			continue;
+
+		if (!data->hist[cpu].irq_count && !data->hist[cpu].thread_count)
+			continue;
+
+		if (!params->no_irq) {
+			if (data->hist[cpu].irq_count)
+				trace_seq_printf(trace->seq, "%9llu ",
+						 data->hist[cpu].sum_irq / data->hist[cpu].irq_count);
+			else
+				trace_seq_printf(trace->seq, "        - ");
+		}
+
+		if (!params->no_thread) {
+			if (data->hist[cpu].thread_count)
+				trace_seq_printf(trace->seq, "%9llu ",
+						data->hist[cpu].sum_thread / data->hist[cpu].thread_count);
+			else
+				trace_seq_printf(trace->seq, "        - ");
+		}
+	}
+	trace_seq_printf(trace->seq, "\n");
+
+	if (!params->no_index)
+		trace_seq_printf(trace->seq, "max:  ");
+
+	for (cpu = 0; cpu < data->nr_cpus; cpu++) {
+		if (params->cpus && !params->monitored_cpus[cpu])
+			continue;
+
+		if (!data->hist[cpu].irq_count && !data->hist[cpu].thread_count)
+			continue;
+
+		if (!params->no_irq)
+			trace_seq_printf(trace->seq, "%9llu ",
+					data->hist[cpu].max_irq);
+
+		if (!params->no_thread)
+			trace_seq_printf(trace->seq, "%9llu ",
+					data->hist[cpu].max_thread);
+	}
+	trace_seq_printf(trace->seq, "\n");
+	trace_seq_do_printf(trace->seq);
+	trace_seq_reset(trace->seq);
+}
+
+/*
+ * timerlat_print_stats - print data for all CPUs
+ */
+static void
+timerlat_print_stats(struct timerlat_hist_params *params, struct osnoise_tool *tool)
+{
+	struct timerlat_hist_data *data = tool->data;
+	struct trace_instance *trace = &tool->trace;
+	int bucket, cpu;
+	int total;
+
+	timerlat_hist_header(tool);
+
+	for (bucket = 0; bucket < data->entries; bucket++) {
+		total = 0;
+
+		if (!params->no_index)
+			trace_seq_printf(trace->seq, "%-6d",
+					 bucket * data->bucket_size);
+
+		for (cpu = 0; cpu < data->nr_cpus; cpu++) {
+			if (params->cpus && !params->monitored_cpus[cpu])
+				continue;
+
+			if (!data->hist[cpu].irq_count && !data->hist[cpu].thread_count)
+				continue;
+
+			if (!params->no_irq) {
+				total += data->hist[cpu].irq[bucket];
+				trace_seq_printf(trace->seq, "%9d ",
+						data->hist[cpu].irq[bucket]);
+			}
+
+			if (!params->no_thread) {
+				total += data->hist[cpu].thread[bucket];
+				trace_seq_printf(trace->seq, "%9d ",
+						data->hist[cpu].thread[bucket]);
+			}
+
+		}
+
+		if (total == 0 && !params->with_zeros) {
+			trace_seq_reset(trace->seq);
+			continue;
+		}
+
+		trace_seq_printf(trace->seq, "\n");
+		trace_seq_do_printf(trace->seq);
+		trace_seq_reset(trace->seq);
+	}
+
+	if (!params->no_index)
+		trace_seq_printf(trace->seq, "over: ");
+
+	for (cpu = 0; cpu < data->nr_cpus; cpu++) {
+		if (params->cpus && !params->monitored_cpus[cpu])
+			continue;
+
+		if (!data->hist[cpu].irq_count && !data->hist[cpu].thread_count)
+			continue;
+
+		if (!params->no_irq)
+			trace_seq_printf(trace->seq, "%9d ",
+					 data->hist[cpu].irq[data->entries]);
+
+		if (!params->no_thread)
+			trace_seq_printf(trace->seq, "%9d ",
+					 data->hist[cpu].thread[data->entries]);
+	}
+	trace_seq_printf(trace->seq, "\n");
+	trace_seq_do_printf(trace->seq);
+	trace_seq_reset(trace->seq);
+
+	timerlat_print_summary(params, trace, data);
+}
+
+/*
+ * timerlat_hist_usage - prints timerlat top usage message
+ */
+static void timerlat_hist_usage(char *usage)
+{
+	int i;
+
+	char *msg[] = {
+		"",
+		"  usage: [rtla] timerlat hist [-h] [-q] [-d s] [-D] [-n] [-p us] [-i us] [-T us] [-s us] [-t[=file]] \\",
+		"         [-c cpu-list] [-P priority] [-e N] [-b N]  [--no-irq] [--no-thread] [--no-header] [--no-summary] \\",
+		"         [--no-index] [--with-zeros]",
+		"",
+		"	  -h/--help: print this menu",
+		"	  -p/--period us: timerlat period in us",
+		"	  -i/--irq us: stop trace if the irq latency is higher than the argument in us",
+		"	  -T/--thread us: stop trace if the thread latency is higher than the argument in us",
+		"	  -s/--stack us: save the stack trace at the IRQ if a thread latency is higher than the argument in us",
+		"	  -c/--cpus cpus: run the tracer only on the given cpus",
+		"	  -d/--duration time[m|h|d]: duration of the session in seconds",
+		"	  -D/--debug: print debug info",
+		"	  -T/--trace[=file]: save the stopped trace to [file|timerlat_trace.txt]",
+		"	  -n/--nano: display data in nanoseconds",
+		"	  -b/--bucket-size N: set the histogram bucket size (default 1)",
+		"	  -e/--entries N: set the number of entries of the histogram (default 256)",
+		"	     --no-irq: ignore IRQ latencies",
+		"	     --no-thread: ignore thread latencies",
+		"	     --no-header: do not print header",
+		"	     --no-summary: do not print summary",
+		"	     --no-index: do not print index",
+		"	     --with-zeros: print zero only entries",
+		"	  -P/--priority o:prio|r:prio|f:prio|d:runtime:period : set scheduling parameters",
+		"		o:prio - use SCHED_OTHER with prio",
+		"		r:prio - use SCHED_RR with prio",
+		"		f:prio - use SCHED_FIFO with prio",
+		"		d:runtime[us|ms|s]:period[us|ms|s] - use SCHED_DEADLINE with runtime and period",
+		"						       in nanoseconds",
+		NULL,
+	};
+
+	if (usage)
+		fprintf(stderr, "%s\n", usage);
+
+	fprintf(stderr, "rtla timerlat hist: a per-cpu histogram of the timer latency (version %s)\n",
+			VERSION);
+
+	for (i = 0; msg[i]; i++)
+		fprintf(stderr, "%s\n", msg[i]);
+	exit(1);
+}
+
+/*
+ * timerlat_hist_parse_args - allocs, parse and fill the cmd line parameters
+ */
+static struct timerlat_hist_params
+*timerlat_hist_parse_args(int argc, char *argv[])
+{
+	struct timerlat_hist_params *params;
+	int retval;
+	int c;
+
+	params = calloc(1, sizeof(*params));
+	if (!params)
+		exit(1);
+
+	/* display data in microseconds */
+	params->output_divisor = 1000;
+	params->bucket_size = 1;
+	params->entries = 256;
+
+	while (1) {
+		static struct option long_options[] = {
+			{"cpus",		required_argument,	0, 'c'},
+			{"bucket-size",		required_argument,	0, 'b'},
+			{"debug",		no_argument,		0, 'D'},
+			{"entries",		required_argument,	0, 'e'},
+			{"duration",		required_argument,	0, 'd'},
+			{"help",		no_argument,		0, 'h'},
+			{"irq",			required_argument,	0, 'i'},
+			{"nano",		no_argument,		0, 'n'},
+			{"period",		required_argument,	0, 'p'},
+			{"priority",		required_argument,	0, 'P'},
+			{"stack",		required_argument,	0, 's'},
+			{"thread",		required_argument,	0, 'T'},
+			{"trace",		optional_argument,	0, 't'},
+			{"no-irq",		no_argument,		0, '0'},
+			{"no-thread",		no_argument,		0, '1'},
+			{"no-header",		no_argument,		0, '2'},
+			{"no-summary",		no_argument,		0, '3'},
+			{"no-index",		no_argument,		0, '4'},
+			{"with-zeros",		no_argument,		0, '5'},
+			{0, 0, 0, 0}
+		};
+
+		/* getopt_long stores the option index here. */
+		int option_index = 0;
+
+		c = getopt_long(argc, argv, "c:b:d:e:Dhi:np:P:s:t::T:012345",
+				 long_options, &option_index);
+
+		/* detect the end of the options. */
+		if (c == -1)
+			break;
+
+		switch (c) {
+		case 'c':
+			retval = parse_cpu_list(optarg, &params->monitored_cpus);
+			if (retval)
+				timerlat_hist_usage("\nInvalid -c cpu list\n");
+			params->cpus = optarg;
+			break;
+		case 'b':
+			params->bucket_size = get_llong_from_str(optarg);
+			if ((params->bucket_size == 0) || (params->bucket_size >= 1000000))
+				timerlat_hist_usage("Bucket size needs to be > 0 and <= 1000000\n");
+			break;
+		case 'D':
+			config_debug = 1;
+			break;
+		case 'd':
+			params->duration = parse_seconds_duration(optarg);
+			if (!params->duration)
+				timerlat_hist_usage("Invalid -D duration\n");
+			break;
+		case 'e':
+			params->entries = get_llong_from_str(optarg);
+			if ((params->entries < 10) || (params->entries > 9999999))
+					timerlat_hist_usage("Entries must be > 10 and < 9999999\n");
+			break;
+		case 'h':
+		case '?':
+			timerlat_hist_usage(NULL);
+			break;
+		case 'i':
+			params->stop_us = get_llong_from_str(optarg);
+			break;
+		case 'n':
+			params->output_divisor = 1;
+			break;
+		case 'p':
+			params->timerlat_period_us = get_llong_from_str(optarg);
+			if (params->timerlat_period_us > 1000000)
+				timerlat_hist_usage("Period longer than 1 s\n");
+			break;
+		case 'P':
+			retval = parse_prio(optarg, &params->sched_param);
+			if (retval == -1)
+				timerlat_hist_usage("Invalid -P priority");
+			params->set_sched = 1;
+			break;
+		case 's':
+			params->print_stack = get_llong_from_str(optarg);
+			break;
+		case 'T':
+			params->stop_total_us = get_llong_from_str(optarg);
+			break;
+		case 't':
+			if (optarg)
+				/* skip = */
+				params->trace_output = &optarg[1];
+			else
+				params->trace_output = "timerlat_trace.txt";
+			break;
+		case '0': /* no irq */
+			params->no_irq = 1;
+			break;
+		case '1': /* no thread */
+			params->no_thread = 1;
+			break;
+		case '2': /* no header */
+			params->no_header = 1;
+			break;
+		case '3': /* no summary */
+			params->no_summary = 1;
+			break;
+		case '4': /* no index */
+			params->no_index = 1;
+			break;
+		case '5': /* with zeros */
+			params->with_zeros = 1;
+			break;
+		default:
+			timerlat_hist_usage("Invalid option");
+		}
+	}
+
+	if (geteuid()) {
+		err_msg("rtla needs root permission\n");
+		exit(EXIT_FAILURE);
+	}
+
+	if (params->no_irq && params->no_thread)
+		timerlat_hist_usage("no-irq and no-thread set, there is nothing to do here");
+
+	if (params->no_index && !params->with_zeros)
+		timerlat_hist_usage("no-index set with with-zeros is not set - it does not make sense");
+
+	return params;
+}
+
+/*
+ * timerlat_hist_apply_config - apply the hist configs to the initialized tool
+ */
+static int
+timerlat_hist_apply_config(struct osnoise_tool *tool, struct timerlat_hist_params *params)
+{
+	int retval;
+
+	if (!params->sleep_time)
+		params->sleep_time = 1;
+
+	if (params->cpus) {
+		retval = osnoise_set_cpus(tool->context, params->cpus);
+		if (retval) {
+			err_msg("Failed to apply CPUs config\n");
+			goto out_err;
+		}
+	}
+
+	if (params->stop_us) {
+		retval = osnoise_set_stop_us(tool->context, params->stop_us);
+		if (retval) {
+			err_msg("Failed to set stop us\n");
+			goto out_err;
+		}
+	}
+
+	if (params->stop_total_us) {
+		retval = osnoise_set_stop_total_us(tool->context, params->stop_total_us);
+		if (retval) {
+			err_msg("Failed to set stop total us\n");
+			goto out_err;
+		}
+	}
+
+	if (params->timerlat_period_us) {
+		retval = osnoise_set_timerlat_period_us(tool->context, params->timerlat_period_us);
+		if (retval) {
+			err_msg("Failed to set timerlat period\n");
+			goto out_err;
+		}
+	}
+
+	if (params->print_stack) {
+		retval = osnoise_set_print_stack(tool->context, params->print_stack);
+		if (retval) {
+			err_msg("Failed to set print stack\n");
+			goto out_err;
+		}
+	}
+
+	return 0;
+
+out_err:
+	return -1;
+}
+
+/*
+ * timerlat_init_hist - initialize a timerlat hist tool with parameters
+ */
+static struct osnoise_tool
+*timerlat_init_hist(struct timerlat_hist_params *params)
+{
+	struct osnoise_tool *tool;
+	int nr_cpus;
+
+	nr_cpus = sysconf(_SC_NPROCESSORS_CONF);
+
+	tool = osnoise_init_tool("timerlat_hist");
+	if (!tool)
+		return NULL;
+
+	tool->data = timerlat_alloc_histogram(nr_cpus, params->entries, params->bucket_size);
+	if (!tool->data)
+		goto out_err;
+
+	tool->params = params;
+
+	tep_register_event_handler(tool->trace.tep, -1, "ftrace", "timerlat",
+				   timerlat_hist_handler, tool);
+
+	return tool;
+
+out_err:
+	osnoise_destroy_tool(tool);
+	return NULL;
+}
+
+static int stop_tracing;
+static void stop_hist(int sig)
+{
+	stop_tracing = 1;
+}
+
+/*
+ * timerlat_hist_set_signals - handles the signal to stop the tool
+ */
+static void
+timerlat_hist_set_signals(struct timerlat_hist_params *params)
+{
+	signal(SIGINT, stop_hist);
+	if (params->duration) {
+		signal(SIGALRM, stop_hist);
+		alarm(params->duration);
+	}
+}
+
+int timerlat_hist_main(int argc, char *argv[])
+{
+	struct timerlat_hist_params *params;
+	struct trace_instance *trace;
+	struct osnoise_tool *record;
+	struct osnoise_tool *tool;
+	int return_value = 1;
+	int retval;
+
+	params = timerlat_hist_parse_args(argc, argv);
+	if (!params)
+		exit(1);
+
+	tool = timerlat_init_hist(params);
+	if (!tool) {
+		err_msg("Could not init osnoise hist\n");
+		goto out_exit;
+	}
+
+	retval = timerlat_hist_apply_config(tool, params);
+	if (retval) {
+		err_msg("Could not apply config\n");
+		goto out_hist;
+	}
+
+	trace = &tool->trace;
+
+	retval = enable_timerlat(trace);
+	if (retval) {
+		err_msg("Failed to enable timerlat tracer\n");
+		goto out_hist;
+	}
+
+	if (params->set_sched) {
+		retval = set_comm_sched_attr("timerlat/", &params->sched_param);
+		if (retval) {
+			err_msg("Failed to set sched parameters\n");
+			goto out_hist;
+		}
+	}
+
+	trace_instance_start(trace);
+
+	if (params->trace_output) {
+		record = osnoise_init_trace_tool("timerlat");
+		if (!record) {
+			err_msg("Failed to enable the trace instance\n");
+			goto out_hist;
+		}
+		trace_instance_start(&record->trace);
+	}
+
+	tool->start_time = time(NULL);
+	timerlat_hist_set_signals(params);
+
+	while (!stop_tracing) {
+		sleep(params->sleep_time);
+
+		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");
+			goto out_hist;
+		}
+
+		if (!tracefs_trace_is_on(trace->inst))
+			break;
+	};
+
+	timerlat_print_stats(params, tool);
+
+	return_value = 0;
+
+	if (!tracefs_trace_is_on(trace->inst)) {
+		printf("rtla timelat hit stop tracing\n");
+		if (params->trace_output) {
+			printf("  Saving trace to %s\n", params->trace_output);
+			save_trace_to_file(record->trace.inst, params->trace_output);
+		}
+	}
+
+out_hist:
+	timerlat_free_histogram(tool->data);
+	osnoise_destroy_tool(tool);
+	if (params->trace_output)
+		osnoise_destroy_tool(record);
+	free(params);
+out_exit:
+	exit(return_value);
+}