RTLA: An interface for osnoise/timerlat tracers

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new file mode 100644
index 000000000000..ab11c29cdcc2
@@ -0,0 +1,192 @@
+// SPDX-License-Identifier: GPL-2.0
+#define _GNU_SOURCE
+#include <sys/sendfile.h>
+#include <tracefs.h>
+#include <signal.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <errno.h>
+
+#include "trace.h"
+#include "utils.h"
+
+/*
+ * enable_tracer_by_name - enable a tracer on the given instance
+ */
+int enable_tracer_by_name(struct tracefs_instance *inst, const char *tracer)
+{
+	enum tracefs_tracers t;
+	int retval;
+
+	t = TRACEFS_TRACER_CUSTOM;
+
+	debug_msg("enabling %s tracer\n", tracer);
+
+	retval = tracefs_tracer_set(inst, t, tracer);
+	if (retval < 0) {
+		if (errno == ENODEV)
+			err_msg("tracer %s not found!\n", tracer);
+
+		err_msg("failed to enable the tracer %s\n", tracer);
+		return -1;
+	}
+
+	return 0;
+}
+
+/*
+ * disable_tracer - set nop tracer to the insta
+ */
+void disable_tracer(struct tracefs_instance *inst)
+{
+	enum tracefs_tracers t = TRACEFS_TRACER_NOP;
+	int retval;
+
+	retval = tracefs_tracer_set(inst, t);
+	if (retval < 0)
+		err_msg("oops, error disabling tracer\n");
+}
+
+/*
+ * create_instance - create a trace instance with *instance_name
+ */
+struct tracefs_instance *create_instance(char *instance_name)
+{
+	return tracefs_instance_create(instance_name);
+}
+
+/*
+ * destroy_instance - remove a trace instance and free the data
+ */
+void destroy_instance(struct tracefs_instance *inst)
+{
+	tracefs_instance_destroy(inst);
+	tracefs_instance_free(inst);
+}
+
+/*
+ * save_trace_to_file - save the trace output of the instance to the file
+ */
+int save_trace_to_file(struct tracefs_instance *inst, const char *filename)
+{
+	const char *file = "trace";
+	mode_t mode = 0644;
+	char *buffer[4096];
+	int out_fd, in_fd;
+	int retval = -1;
+
+	in_fd = tracefs_instance_file_open(inst, file, O_RDONLY);
+	if (in_fd < 0) {
+		err_msg("Failed to open trace file\n");
+		return -1;
+	}
+
+	out_fd = creat(filename, mode);
+	if (out_fd < 0) {
+		err_msg("Failed to create output file %s\n", filename);
+		goto out_close_in;
+	}
+
+	do {
+		retval = read(in_fd, buffer, sizeof(buffer));
+		if (retval <= 0)
+			goto out_close;
+
+		retval = write(out_fd, buffer, retval);
+		if (retval < 0)
+			goto out_close;
+	} while (retval > 0);
+
+	retval = 0;
+out_close:
+	close(out_fd);
+out_close_in:
+	close(in_fd);
+	return retval;
+}
+
+/*
+ * collect_registered_events - call the existing callback function for the event
+ *
+ * If an event has a registered callback function, call it.
+ * Otherwise, ignore the event.
+ */
+int
+collect_registered_events(struct tep_event *event, struct tep_record *record,
+			  int cpu, void *context)
+{
+	struct trace_instance *trace = context;
+	struct trace_seq *s = trace->seq;
+
+	if (!event->handler)
+		return 0;
+
+	event->handler(s, record, event, context);
+
+	return 0;
+}
+
+/*
+ * trace_instance_destroy - destroy and free a rtla trace instance
+ */
+void trace_instance_destroy(struct trace_instance *trace)
+{
+	if (trace->inst) {
+		disable_tracer(trace->inst);
+		destroy_instance(trace->inst);
+	}
+
+	if (trace->seq)
+		free(trace->seq);
+
+	if (trace->tep)
+		tep_free(trace->tep);
+}
+
+/*
+ * trace_instance_init - create an rtla trace instance
+ *
+ * It is more than the tracefs instance, as it contains other
+ * things required for the tracing, such as the local events and
+ * a seq file.
+ *
+ * Note that the trace instance is returned disabled. This allows
+ * the tool to apply some other configs, like setting priority
+ * to the kernel threads, before starting generating trace entries.
+ */
+int trace_instance_init(struct trace_instance *trace, char *tool_name)
+{
+	trace->seq = calloc(1, sizeof(*trace->seq));
+	if (!trace->seq)
+		goto out_err;
+
+	trace_seq_init(trace->seq);
+
+	trace->inst = create_instance(tool_name);
+	if (!trace->inst)
+		goto out_err;
+
+	trace->tep = tracefs_local_events(NULL);
+	if (!trace->tep)
+		goto out_err;
+
+	/*
+	 * Let the main enable the record after setting some other
+	 * things such as the priority of the tracer's threads.
+	 */
+	tracefs_trace_off(trace->inst);
+
+	return 0;
+
+out_err:
+	trace_instance_destroy(trace);
+	return 1;
+}
+
+/*
+ * trace_instance_start - start tracing a given rtla instance
+ */
+int trace_instance_start(struct trace_instance *trace)
+{
+	return tracefs_trace_on(trace->inst);
+}

new file mode 100644
index 000000000000..7c3930909b70
@@ -0,0 +1,27 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <tracefs.h>
+#include <stddef.h>
+
+struct trace_instance {
+	struct tracefs_instance		*inst;
+	struct tep_handle		*tep;
+	struct trace_seq		*seq;
+};
+
+int trace_instance_init(struct trace_instance *trace, char *tool_name);
+int trace_instance_start(struct trace_instance *trace);
+void trace_instance_destroy(struct trace_instance *trace);
+
+struct trace_seq *get_trace_seq(void);
+int enable_tracer_by_name(struct tracefs_instance *inst, const char *tracer);
+void disable_tracer(struct tracefs_instance *inst);
+
+int enable_osnoise(struct trace_instance *trace);
+int enable_timerlat(struct trace_instance *trace);
+
+struct tracefs_instance *create_instance(char *instance_name);
+void destroy_instance(struct tracefs_instance *inst);
+
+int save_trace_to_file(struct tracefs_instance *inst, const char *filename);
+int collect_registered_events(struct tep_event *tep, struct tep_record *record,
+			      int cpu, void *context);

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index 5ae2664ed47d..669b9750b3b3 100644
@@ -8,6 +8,8 @@
 #include <string.h>
 #include <stdio.h>
 
+#include "osnoise.h"
+
 /*
  * rtla_usage - print rtla usage
  */

@@ -22,6 +24,7 @@ static void rtla_usage(void)
 		"  usage: rtla COMMAND ...",
 		"",
 		"  commands:",
+		"     osnoise  - gives information about the operating system noise (osnoise)",
 		"",
 		NULL,
 	};

@@ -39,7 +42,14 @@ static void rtla_usage(void)
  */
 int run_command(int argc, char **argv, int start_position)
 {
+	if (strcmp(argv[start_position], "osnoise") == 0) {
+		osnoise_main(argc-start_position, &argv[start_position]);
+		goto ran;
+	}
+
 	return 0;
+ran:
+	return 1;
 }
 
 int main(int argc, char *argv[])

index 7ef686dddc09..d8bde8e45710 100644
@@ -970,7 +970,8 @@ static void osnoise_usage(void)
 		"  usage: [rtla] osnoise [MODE] ...",
 		"",
 		"  modes:",
-		"     top  - prints the summary from osnoise tracer",
+		"     top   - prints the summary from osnoise tracer",
+		"     hist  - prints a histogram of osnoise samples",
 		"",
 		"if no MODE is given, the top mode is called, passing the arguments",
 		NULL,

@@ -1005,6 +1006,9 @@ int osnoise_main(int argc, char *argv[])
 	} else if (strcmp(argv[1], "top") == 0) {
 		osnoise_top_main(argc-1, &argv[1]);
 		exit(0);
+	} else if (strcmp(argv[1], "hist") == 0) {
+		osnoise_hist_main(argc-1, &argv[1]);
+		exit(0);
 	}
 
 usage:

index e3e8f8359d99..f6c9fe05c744 100644
@@ -91,5 +91,6 @@ void osnoise_destroy_tool(struct osnoise_tool *top);
 struct osnoise_tool *osnoise_init_tool(char *tool_name);
 struct osnoise_tool *osnoise_init_trace_tool(char *tracer);
 
+int osnoise_hist_main(int argc, char *argv[]);
 int osnoise_top_main(int argc, char **argv);
 int osnoise_main(int argc, char **argv);

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index 669b9750b3b3..09bd21b8af81 100644
@@ -9,6 +9,7 @@
 #include <stdio.h>
 
 #include "osnoise.h"
+#include "timerlat.h"
 
 /*
  * rtla_usage - print rtla usage

@@ -25,6 +26,7 @@ static void rtla_usage(void)
 		"",
 		"  commands:",
 		"     osnoise  - gives information about the operating system noise (osnoise)",
+		"     timerlat - measures the timer irq and thread latency",
 		"",
 		NULL,
 	};

@@ -45,6 +47,9 @@ int run_command(int argc, char **argv, int start_position)
 	if (strcmp(argv[start_position], "osnoise") == 0) {
 		osnoise_main(argc-start_position, &argv[start_position]);
 		goto ran;
+	} else if (strcmp(argv[start_position], "timerlat") == 0) {
+		timerlat_main(argc-start_position, &argv[start_position]);
+		goto ran;
 	}
 
 	return 0;

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new file mode 100644
index 000000000000..6f9d3925acd0
@@ -0,0 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
+
+int timerlat_top_main(int argc, char *argv[]);
+int timerlat_main(int argc, char *argv[]);

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index 29a51c01b084..97abbf494fee 100644
@@ -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:

index 6f9d3925acd0..88561bfd14f3 100644
@@ -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[]);

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new file mode 100644
index 000000000000..e23bae8d9696
@@ -0,0 +1,577 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2021 Red Hat Inc, Daniel Bristot de Oliveira <[email protected]>
+ */
+
+#include <getopt.h>
+#include <stdlib.h>
+#include <string.h>
+#include <signal.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <time.h>
+
+#include "osnoise.h"
+#include "utils.h"
+
+/*
+ * osnoise top parameters
+ */
+struct osnoise_top_params {
+	char			*cpus;
+	char			*monitored_cpus;
+	char			*trace_output;
+	unsigned long long	runtime;
+	unsigned long long	period;
+	long long		stop_us;
+	long long		stop_total_us;
+	int			sleep_time;
+	int			duration;
+	int			quiet;
+	int			set_sched;
+	struct sched_attr	sched_param;
+};
+
+struct osnoise_top_cpu {
+	unsigned long long	sum_runtime;
+	unsigned long long	sum_noise;
+	unsigned long long	max_noise;
+	unsigned long long	max_sample;
+
+	unsigned long long	hw_count;
+	unsigned long long	nmi_count;
+	unsigned long long	irq_count;
+	unsigned long long	softirq_count;
+	unsigned long long	thread_count;
+
+	int			sum_cycles;
+};
+
+struct osnoise_top_data {
+	struct osnoise_top_cpu	*cpu_data;
+	int			nr_cpus;
+};
+
+/*
+ * osnoise_free_top - free runtime data
+ */
+static void
+osnoise_free_top(struct osnoise_top_data *data)
+{
+	free(data->cpu_data);
+	free(data);
+}
+
+/*
+ * osnoise_alloc_histogram - alloc runtime data
+ */
+static struct osnoise_top_data *osnoise_alloc_top(int nr_cpus)
+{
+	struct osnoise_top_data *data;
+
+	data = calloc(1, sizeof(*data));
+	if (!data)
+		return NULL;
+
+	data->nr_cpus = nr_cpus;
+
+	/* one set of histograms per CPU */
+	data->cpu_data = calloc(1, sizeof(*data->cpu_data) * nr_cpus);
+	if (!data->cpu_data)
+		goto cleanup;
+
+	return data;
+
+cleanup:
+	osnoise_free_top(data);
+	return NULL;
+}
+
+/*
+ * osnoise_top_handler - this is the handler for osnoise tracer events
+ */
+static int
+osnoise_top_handler(struct trace_seq *s, struct tep_record *record,
+		    struct tep_event *event, void *context)
+{
+	struct trace_instance *trace = context;
+	struct osnoise_tool *tool;
+	unsigned long long val;
+	struct osnoise_top_cpu *cpu_data;
+	struct osnoise_top_data *data;
+	int cpu = record->cpu;
+
+	tool = container_of(trace, struct osnoise_tool, trace);
+
+	data = tool->data;
+	cpu_data = &data->cpu_data[cpu];
+
+	cpu_data->sum_cycles++;
+
+	tep_get_field_val(s, event, "runtime", record, &val, 1);
+	update_sum(&cpu_data->sum_runtime, &val);
+
+	tep_get_field_val(s, event, "noise", record, &val, 1);
+	update_max(&cpu_data->max_noise, &val);
+	update_sum(&cpu_data->sum_noise, &val);
+
+	tep_get_field_val(s, event, "max_sample", record, &val, 1);
+	update_max(&cpu_data->max_sample, &val);
+
+	tep_get_field_val(s, event, "hw_count", record, &val, 1);
+	update_sum(&cpu_data->hw_count, &val);
+
+	tep_get_field_val(s, event, "nmi_count", record, &val, 1);
+	update_sum(&cpu_data->nmi_count, &val);
+
+	tep_get_field_val(s, event, "irq_count", record, &val, 1);
+	update_sum(&cpu_data->irq_count, &val);
+
+	tep_get_field_val(s, event, "softirq_count", record, &val, 1);
+	update_sum(&cpu_data->softirq_count, &val);
+
+	tep_get_field_val(s, event, "thread_count", record, &val, 1);
+	update_sum(&cpu_data->thread_count, &val);
+
+	return 0;
+}
+
+/*
+ * osnoise_top_header - print the header of the tool output
+ */
+static void osnoise_top_header(struct osnoise_tool *top)
+{
+	struct trace_seq *s = top->trace.seq;
+	char duration[26];
+
+	get_duration(top->start_time, duration, sizeof(duration));
+
+	trace_seq_printf(s, "\033[2;37;40m");
+	trace_seq_printf(s, "                                          Operating System Noise");
+	trace_seq_printf(s, "                                     ");
+	trace_seq_printf(s, "                                     ");
+	trace_seq_printf(s, "\033[0;0;0m");
+	trace_seq_printf(s, "\n");
+
+	trace_seq_printf(s, "duration: %9s | time is in us\n", duration);
+
+	trace_seq_printf(s, "\033[2;30;47m");
+	trace_seq_printf(s, "CPU Period       Runtime ");
+	trace_seq_printf(s, "       Noise ");
+	trace_seq_printf(s, " %% CPU Aval ");
+	trace_seq_printf(s, "  Max Noise   Max Single ");
+	trace_seq_printf(s, "         HW          NMI          IRQ      Softirq       Thread");
+	trace_seq_printf(s, "\033[0;0;0m");
+	trace_seq_printf(s, "\n");
+}
+
+/*
+ * clear_terminal - clears the output terminal
+ */
+static void clear_terminal(struct trace_seq *seq)
+{
+	if (!config_debug)
+		trace_seq_printf(seq, "\033c");
+}
+
+/*
+ * osnoise_top_print - prints the output of a given CPU
+ */
+static void osnoise_top_print(struct osnoise_tool *tool, int cpu)
+{
+	struct trace_seq *s = tool->trace.seq;
+	struct osnoise_top_cpu *cpu_data;
+	struct osnoise_top_data *data;
+	int percentage;
+	int decimal;
+
+	data = tool->data;
+	cpu_data = &data->cpu_data[cpu];
+
+	if (!cpu_data->sum_runtime)
+		return;
+
+	percentage = ((cpu_data->sum_runtime - cpu_data->sum_noise) * 10000000)
+			/ cpu_data->sum_runtime;
+	decimal = percentage % 100000;
+	percentage = percentage / 100000;
+
+	trace_seq_printf(s, "%3d #%-6d %12llu ", cpu, cpu_data->sum_cycles, cpu_data->sum_runtime);
+	trace_seq_printf(s, "%12llu ", cpu_data->sum_noise);
+	trace_seq_printf(s, "  %3d.%05d", percentage, decimal);
+	trace_seq_printf(s, "%12llu %12llu", cpu_data->max_noise, cpu_data->max_sample);
+
+	trace_seq_printf(s, "%12llu ", cpu_data->hw_count);
+	trace_seq_printf(s, "%12llu ", cpu_data->nmi_count);
+	trace_seq_printf(s, "%12llu ", cpu_data->irq_count);
+	trace_seq_printf(s, "%12llu ", cpu_data->softirq_count);
+	trace_seq_printf(s, "%12llu\n", cpu_data->thread_count);
+}
+
+/*
+ * osnoise_print_stats - print data for all cpus
+ */
+static void
+osnoise_print_stats(struct osnoise_top_params *params, struct osnoise_tool *top)
+{
+	struct trace_instance *trace = &top->trace;
+	static int nr_cpus = -1;
+	int i;
+
+	if (nr_cpus == -1)
+		nr_cpus = sysconf(_SC_NPROCESSORS_CONF);
+
+	if (!params->quiet)
+		clear_terminal(trace->seq);
+
+	osnoise_top_header(top);
+
+	for (i = 0; i < nr_cpus; i++) {
+		if (params->cpus && !params->monitored_cpus[i])
+			continue;
+		osnoise_top_print(top, i);
+	}
+
+	trace_seq_do_printf(trace->seq);
+	trace_seq_reset(trace->seq);
+}
+
+/*
+ * osnoise_top_usage - prints osnoise top usage message
+ */
+void osnoise_top_usage(char *usage)
+{
+	int i;
+
+	static const char * const msg[] = {
+		"  usage: rtla osnoise [top] [-h] [-q] [-p us] [-r us] [-s us] [-S us] [-T[=file]] \\",
+		"	  [-c cpu-list] -P priority",
+		"",
+		"	  -h/--help: print this menu",
+		"	  -p/--period us: osnoise period in us",
+		"	  -r/--runtime us: osnoise runtime in us",
+		"	  -s/--stop us: stop trace if a single sample is higher than the argument in us",
+		"	  -S/--stop-total us: stop trace if the total sample is higher than the argument in us",
+		"	  -c/--cpus cpu-list: list of cpus to run osnoise threads",
+		"	  -d/--duration time[s|m|h|d]: duration of the session",
+		"	  -t/--trace[=file]: save the stopped trace to [file|osnoise_trace.txt]",
+		"	  -q/--quiet print only a summary at the end",
+		"	  -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 osnoise top: a per-cpu summary of the OS noise (version %s)\n",
+			VERSION);
+
+	for (i = 0; msg[i]; i++)
+		fprintf(stderr, "%s\n", msg[i]);
+	exit(1);
+}
+
+/*
+ * osnoise_top_parse_args - allocs, parse and fill the cmd line parameters
+ */
+struct osnoise_top_params *osnoise_top_parse_args(int argc, char **argv)
+{
+	struct osnoise_top_params *params;
+	int retval;
+	int c;
+
+	params = calloc(1, sizeof(*params));
+	if (!params)
+		exit(1);
+
+	while (1) {
+		static struct option long_options[] = {
+			{"cpus",		required_argument,	0, 'c'},
+			{"debug",		no_argument,		0, 'D'},
+			{"duration",		required_argument,	0, 'd'},
+			{"help",		no_argument,		0, 'h'},
+			{"period",		required_argument,	0, 'p'},
+			{"priority",		required_argument,	0, 'P'},
+			{"quiet",		no_argument,		0, 'q'},
+			{"runtime",		required_argument,	0, 'r'},
+			{"stop",		required_argument,	0, 's'},
+			{"stop-total",		required_argument,	0, 'S'},
+			{"trace",		optional_argument,	0, 't'},
+			{0, 0, 0, 0}
+		};
+
+		/* getopt_long stores the option index here. */
+		int option_index = 0;
+
+		c = getopt_long(argc, argv, "c:d:Dhp:P:qr:s:S:t::",
+				 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)
+				osnoise_top_usage("\nInvalid -c cpu list\n");
+			params->cpus = optarg;
+			debug_msg("-c for %s\n", params->cpus);
+			break;
+		case 'D':
+			config_debug = 1;
+			break;
+		case 'd':
+			params->duration = parse_seconds_duration(optarg);
+			if (!params->duration)
+				osnoise_top_usage("Invalid -D duration\n");
+			break;
+		case 'h':
+		case '?':
+			osnoise_top_usage(NULL);
+			break;
+		case 'p':
+			params->period = get_llong_from_str(optarg);
+			if (params->period > 10000000)
+				osnoise_top_usage("Period longer than 10 s\n");
+			break;
+		case 'P':
+			retval = parse_prio(optarg, &params->sched_param);
+			if (retval == -1)
+				osnoise_top_usage("Invalid -P priority");
+			params->set_sched = 1;
+			break;
+		case 'q':
+			params->quiet = 1;
+			break;
+		case 'r':
+			params->runtime = get_llong_from_str(optarg);
+			if (params->runtime < 100)
+				osnoise_top_usage("Runtime shorter than 100 us\n");
+			break;
+		case 's':
+			params->stop_us = get_llong_from_str(optarg);
+			break;
+		case 'S':
+			params->stop_total_us = get_llong_from_str(optarg);
+			break;
+		case 't':
+			if (optarg)
+				/* skip = */
+				params->trace_output = &optarg[1];
+			else
+				params->trace_output = "osnoise_trace.txt";
+			break;
+		default:
+			osnoise_top_usage("Invalid option");
+		}
+	}
+
+	if (geteuid()) {
+		err_msg("osnoise needs root permission\n");
+		exit(EXIT_FAILURE);
+	}
+
+	return params;
+}
+
+/*
+ * osnoise_top_apply_config - apply the top configs to the initialized tool
+ */
+static int
+osnoise_top_apply_config(struct osnoise_tool *tool, struct osnoise_top_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->runtime || params->period) {
+		retval = osnoise_set_runtime_period(tool->context,
+						    params->runtime,
+						    params->period);
+		if (retval) {
+			err_msg("Failed to set runtime and/or period\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;
+		}
+	}
+
+	return 0;
+
+out_err:
+	return -1;
+}
+
+/*
+ * osnoise_init_top - initialize a osnoise top tool with parameters
+ */
+struct osnoise_tool *osnoise_init_top(struct osnoise_top_params *params)
+{
+	struct osnoise_tool *tool;
+	int nr_cpus;
+
+	nr_cpus = sysconf(_SC_NPROCESSORS_CONF);
+
+	tool = osnoise_init_tool("osnoise_top");
+	if (!tool)
+		return NULL;
+
+	tool->data = osnoise_alloc_top(nr_cpus);
+	if (!tool->data)
+		goto out_err;
+
+	tool->params = params;
+
+	tep_register_event_handler(tool->trace.tep, -1, "ftrace", "osnoise",
+				   osnoise_top_handler, NULL);
+
+	return tool;
+
+out_err:
+	osnoise_free_top(tool->data);
+	osnoise_destroy_tool(tool);
+	return NULL;
+}
+
+static int stop_tracing;
+static void stop_top(int sig)
+{
+	stop_tracing = 1;
+}
+
+/*
+ * osnoise_top_set_signals - handles the signal to stop the tool
+ */
+static void osnoise_top_set_signals(struct osnoise_top_params *params)
+{
+	signal(SIGINT, stop_top);
+	if (params->duration) {
+		signal(SIGALRM, stop_top);
+		alarm(params->duration);
+	}
+}
+
+int osnoise_top_main(int argc, char **argv)
+{
+	struct osnoise_top_params *params;
+	struct trace_instance *trace;
+	struct osnoise_tool *record;
+	struct osnoise_tool *tool;
+	int return_value = 1;
+	int retval;
+
+	params = osnoise_top_parse_args(argc, argv);
+	if (!params)
+		exit(1);
+
+	tool = osnoise_init_top(params);
+	if (!tool) {
+		err_msg("Could not init osnoise top\n");
+		goto out_exit;
+	}
+
+	retval = osnoise_top_apply_config(tool, params);
+	if (retval) {
+		err_msg("Could not apply config\n");
+		goto out_top;
+	}
+
+	trace = &tool->trace;
+
+	retval = enable_osnoise(trace);
+	if (retval) {
+		err_msg("Failed to enable osnoise tracer\n");
+		goto out_top;
+	}
+
+	if (params->set_sched) {
+		retval = set_comm_sched_attr("osnoise/", &params->sched_param);
+		if (retval)
+			osnoise_top_usage("Failed to set sched parameters\n");
+	}
+
+	trace_instance_start(trace);
+
+	if (params->trace_output) {
+		record = osnoise_init_trace_tool("osnoise");
+		if (!record) {
+			err_msg("Failed to enable the trace instance\n");
+			goto out_top;
+		}
+		trace_instance_start(&record->trace);
+	}
+
+	tool->start_time = time(NULL);
+	osnoise_top_set_signals(params);
+
+	do {
+		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_top;
+		}
+
+		if (!params->quiet)
+			osnoise_print_stats(params, tool);
+
+		if (!tracefs_trace_is_on(trace->inst))
+			break;
+
+	} while (!stop_tracing);
+
+	osnoise_print_stats(params, tool);
+
+	return_value = 0;
+
+	if (!tracefs_trace_is_on(trace->inst)) {
+		printf("osnoise 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_top:
+	osnoise_free_top(tool->data);
+	osnoise_destroy_tool(tool);
+	if (params->trace_output)
+		osnoise_destroy_tool(record);
+out_exit:
+	exit(return_value);
+}