Merge tag 'trace-rtla-v5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull RTLA tracing tool updates from Steven Rostedt:
"Real Time Analysis Tool updatesfor 5.18:

- Support for adjusting tracing_threashold

- Add -a (auto) option to make it easier for users to debug in the field

- Add -e option to add more events to the trace

- Add --trigger option to add triggers to events

- Add --filter option to filter events

- Add support to save histograms to the file

- Add --dma-latency to set /dev/cpu_dma_latency

- Other fixes and cleanups"

* tag 'trace-rtla-v5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
rtla: Tools main loop cleanup
rtla/timerlat: Add --dma-latency option
rtla/osnoise: Fix osnoise hist stop tracing message
rtla: Check for trace off also in the trace instance
rtla/trace: Save event histogram output to a file
rtla: Add --filter support
rtla/trace: Add trace event filter helpers
rtla: Add --trigger support
rtla/trace: Add trace event trigger helpers
rtla: Add -e/--event support
rtla/trace: Add trace events helpers
rtla/timerlat: Add the automatic trace option
rtla/osnoise: Add the automatic trace option
rtla/osnoise: Add an option to set the threshold
rtla/osnoise: Add support to adjust the tracing_thresh

Documentation/tools/rtla/common_options.rst

···
 
         Save the stopped trace to [*file|osnoise_trace.txt*].
 
+**-e**, **--event** *sys:event*
+
+        Enable an event in the trace (**-t**) session. The argument can be a specific event, e.g., **-e** *sched:sched_switch*, or all events of a system group, e.g., **-e** *sched*. Multiple **-e** are allowed. It is only active when **-t** or **-a** are set.
+
+**--filter** *<filter>*
+
+        Filter the previous **-e** *sys:event* event with *<filter>*. For further information about event filtering see https://www.kernel.org/doc/html/latest/trace/events.html#event-filtering.
+
+**--trigger** *<trigger>*
+        Enable a trace event trigger to the previous **-e** *sys:event*.
+        If the *hist:* trigger is activated, the output histogram will be automatically saved to a file named *system_event_hist.txt*.
+        For example, the command:
+
+        rtla <command> <mode> -t -e osnoise:irq_noise --trigger="hist:key=desc,duration/1000:sort=desc,duration/1000:vals=hitcount"
+
+        Will automatically save the content of the histogram associated to *osnoise:irq_noise* event in *osnoise_irq_noise_hist.txt*.
+
+        For further information about event trigger see https://www.kernel.org/doc/html/latest/trace/events.html#event-triggers.
+
 **-P**, **--priority** *o:prio|r:prio|f:prio|d:runtime:period*
 
         Set scheduling parameters to the osnoise tracer threads, the format to set the priority are:

Documentation/tools/rtla/common_osnoise_options.rst

···
+**-a**, **--auto** *us*
+
+        Set the automatic trace mode. This mode sets some commonly used options
+        while debugging the system. It is equivalent to use **-s** *us* **-T 1 -t**.
+
 **-p**, **--period** *us*
 
         Set the *osnoise* tracer period in microseconds.
···
 
         Stop the trace if the total sample is higher than the argument in microseconds.
         If **-T** is set, it will also save the trace to the output.
+
+**-T**, **--threshold** *us*
+
+        Specify the minimum delta between two time reads to be considered noise.
+        The default threshold is *5 us*.

Documentation/tools/rtla/common_timerlat_options.rst

···
+**-a**, **--auto** *us*
+
+        Set the automatic trace mode. This mode sets some commonly used options
+        while debugging the system. It is equivalent to use **-T** *us* **-s** *us*
+        **-t**. By default, *timerlat* tracer uses FIFO:95 for *timerlat* threads,
+        thus equilavent to **-P** *f:95*.
+
 **-p**, **--period** *us*
 
         Set the *timerlat* tracer period in microseconds.
···
 
         Save the stack trace at the *IRQ* if a *Thread* latency is higher than the
         argument in us.
+
+**--dma-latency** *us*
+        Set the /dev/cpu_dma_latency to *us*, aiming to bound exit from idle latencies.
+        *cyclictest* sets this value to *0* by default, use **--dma-latency** *0* to have
+        similar results.

tools/tracing/rtla/src/osnoise.c

···
 }
 
 /*
+ * osnoise_get_tracing_thresh - read and save the original "tracing_thresh"
+ */
+static long long
+osnoise_get_tracing_thresh(struct osnoise_context *context)
+{
+	long long tracing_thresh;
+
+	if (context->tracing_thresh != OSNOISE_OPTION_INIT_VAL)
+		return context->tracing_thresh;
+
+	if (context->orig_tracing_thresh != OSNOISE_OPTION_INIT_VAL)
+		return context->orig_tracing_thresh;
+
+	tracing_thresh = osnoise_read_ll_config("tracing_thresh");
+	if (tracing_thresh < 0)
+		goto out_err;
+
+	context->orig_tracing_thresh = tracing_thresh;
+	return tracing_thresh;
+
+out_err:
+	return OSNOISE_OPTION_INIT_VAL;
+}
+
+/*
+ * osnoise_set_tracing_thresh - set "tracing_thresh"
+ */
+int osnoise_set_tracing_thresh(struct osnoise_context *context, long long tracing_thresh)
+{
+	long long curr_tracing_thresh = osnoise_get_tracing_thresh(context);
+	int retval;
+
+	if (curr_tracing_thresh == OSNOISE_OPTION_INIT_VAL)
+		return -1;
+
+	retval = osnoise_write_ll_config("tracing_thresh", tracing_thresh);
+	if (retval < 0)
+		return -1;
+
+	context->tracing_thresh = tracing_thresh;
+
+	return 0;
+}
+
+/*
+ * osnoise_restore_tracing_thresh - restore the original "tracing_thresh"
+ */
+void osnoise_restore_tracing_thresh(struct osnoise_context *context)
+{
+	int retval;
+
+	if (context->orig_tracing_thresh == OSNOISE_OPTION_INIT_VAL)
+		return;
+
+	if (context->orig_tracing_thresh == context->tracing_thresh)
+		goto out_done;
+
+	retval = osnoise_write_ll_config("tracing_thresh", context->orig_tracing_thresh);
+	if (retval < 0)
+		err_msg("Could not restore original tracing_thresh\n");
+
+out_done:
+	context->tracing_thresh = OSNOISE_OPTION_INIT_VAL;
+}
+
+/*
+ * osnoise_put_tracing_thresh - restore original values and cleanup data
+ */
+void osnoise_put_tracing_thresh(struct osnoise_context *context)
+{
+	osnoise_restore_tracing_thresh(context);
+
+	if (context->orig_tracing_thresh == OSNOISE_OPTION_INIT_VAL)
+		return;
+
+	context->orig_tracing_thresh = OSNOISE_OPTION_INIT_VAL;
+}
+
+/*
  * enable_osnoise - enable osnoise tracer in the trace_instance
  */
 int enable_osnoise(struct trace_instance *trace)
···
 	context->orig_print_stack	= OSNOISE_OPTION_INIT_VAL;
 	context->print_stack		= OSNOISE_OPTION_INIT_VAL;
 
+	context->orig_tracing_thresh	= OSNOISE_OPTION_INIT_VAL;
+	context->tracing_thresh		= OSNOISE_OPTION_INIT_VAL;
+
 	osnoise_get_context(context);
 
 	return context;
···
 	osnoise_put_stop_total_us(context);
 	osnoise_put_timerlat_period_us(context);
 	osnoise_put_print_stack(context);
+	osnoise_put_tracing_thresh(context);
 
 	free(context);
 }

tools/tracing/rtla/src/osnoise.h

···
 	long long		orig_timerlat_period_us;
 	long long		timerlat_period_us;
 
+	/* 0 as init value */
+	long long		orig_tracing_thresh;
+	long long		tracing_thresh;
+
 	/* -1 as init value because 0 is disabled */
 	long long		orig_stop_us;
 	long long		stop_us;
···
 int osnoise_set_timerlat_period_us(struct osnoise_context *context,
 				   long long timerlat_period_us);
 void osnoise_restore_timerlat_period_us(struct osnoise_context *context);
+
+int osnoise_set_tracing_thresh(struct osnoise_context *context,
+			       long long tracing_thresh);
+void osnoise_restore_tracing_thresh(struct osnoise_context *context);
 
 void osnoise_restore_print_stack(struct osnoise_context *context);
 int osnoise_set_print_stack(struct osnoise_context *context,

tools/tracing/rtla/src/osnoise_hist.c

···
 	char			*trace_output;
 	unsigned long long	runtime;
 	unsigned long long	period;
+	long long		threshold;
 	long long		stop_us;
 	long long		stop_total_us;
 	int			sleep_time;
···
 	int			set_sched;
 	int			output_divisor;
 	struct sched_attr	sched_param;
+	struct trace_events	*events;
 
 	char			no_header;
 	char			no_summary;
···
 
 	static const char * const msg[] = {
 		"",
-		"  usage: rtla osnoise hist [-h] [-D] [-d s] [-p us] [-r us] [-s us] [-S us] [-t[=file]] \\",
-		"	  [-c cpu-list] [-P priority] [-b N] [-E N] [--no-header] [--no-summary] \\",
-		"	  [--no-index] [--with-zeros]",
+		"  usage: rtla osnoise hist [-h] [-D] [-d s] [-a us] [-p us] [-r us] [-s us] [-S us] \\",
+		"	  [-T us] [-t[=file]] [-e sys[:event]] [--filter <filter>] [--trigger <trigger>] \\",
+		"	  [-c cpu-list] [-P priority] [-b N] [-E N] [--no-header] [--no-summary] [--no-index] \\",
+		"	  [--with-zeros]",
 		"",
 		"	  -h/--help: print this menu",
+		"	  -a/--auto: set automatic trace mode, stopping the session if argument in us sample is hit",
 		"	  -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",
+		"	  -T/--threshold us: the minimum delta to be considered a noise",
 		"	  -c/--cpus cpu-list: list of cpus to run osnoise threads",
 		"	  -d/--duration time[s|m|h|d]: duration of the session",
 		"	  -D/--debug: print debug info",
 		"	  -t/--trace[=file]: save the stopped trace to [file|osnoise_trace.txt]",
+		"	  -e/--event <sys:event>: enable the <sys:event> in the trace instance, multiple -e are allowed",
+		"	     --filter <filter>: enable a trace event filter to the previous -e event",
+		"	     --trigger <trigger>: enable a trace event trigger to the previous -e event",
 		"	  -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-header: do not print header",
···
 *osnoise_hist_parse_args(int argc, char *argv[])
 {
 	struct osnoise_hist_params *params;
+	struct trace_events *tevent;
 	int retval;
 	int c;
 
···
 
 	while (1) {
 		static struct option long_options[] = {
+			{"auto",		required_argument,	0, 'a'},
 			{"bucket-size",		required_argument,	0, 'b'},
 			{"entries",		required_argument,	0, 'E'},
 			{"cpus",		required_argument,	0, 'c'},
···
 			{"stop",		required_argument,	0, 's'},
 			{"stop-total",		required_argument,	0, 'S'},
 			{"trace",		optional_argument,	0, 't'},
+			{"event",		required_argument,	0, 'e'},
+			{"threshold",		required_argument,	0, 'T'},
 			{"no-header",		no_argument,		0, '0'},
 			{"no-summary",		no_argument,		0, '1'},
 			{"no-index",		no_argument,		0, '2'},
 			{"with-zeros",		no_argument,		0, '3'},
+			{"trigger",		required_argument,	0, '4'},
+			{"filter",		required_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:Dhp:P:r:s:S:t::0123",
+		c = getopt_long(argc, argv, "a:c:b:d:e:E:Dhp:P:r:s:S:t::T:01234:5:",
 				 long_options, &option_index);
 
 		/* detect the end of the options. */
···
 			break;
 
 		switch (c) {
+		case 'a':
+			/* set sample stop to auto_thresh */
+			params->stop_us = get_llong_from_str(optarg);
+
+			/* set sample threshold to 1 */
+			params->threshold = 1;
+
+			/* set trace */
+			params->trace_output = "osnoise_trace.txt";
+
+			break;
 		case 'b':
 			params->bucket_size = get_llong_from_str(optarg);
 			if ((params->bucket_size == 0) || (params->bucket_size >= 1000000))
···
 			params->duration = parse_seconds_duration(optarg);
 			if (!params->duration)
 				osnoise_hist_usage("Invalid -D duration\n");
+			break;
+		case 'e':
+			tevent = trace_event_alloc(optarg);
+			if (!tevent) {
+				err_msg("Error alloc trace event");
+				exit(EXIT_FAILURE);
+			}
+
+			if (params->events)
+				tevent->next = params->events;
+
+			params->events = tevent;
 			break;
 		case 'E':
 			params->entries = get_llong_from_str(optarg);
···
 		case 'S':
 			params->stop_total_us = get_llong_from_str(optarg);
 			break;
+		case 'T':
+			params->threshold = get_llong_from_str(optarg);
+			break;
 		case 't':
 			if (optarg)
 				/* skip = */
···
 			break;
 		case '3': /* with zeros */
 			params->with_zeros = 1;
+			break;
+		case '4': /* trigger */
+			if (params->events) {
+				retval = trace_event_add_trigger(params->events, optarg);
+				if (retval) {
+					err_msg("Error adding trigger %s\n", optarg);
+					exit(EXIT_FAILURE);
+				}
+			} else {
+				osnoise_hist_usage("--trigger requires a previous -e\n");
+			}
+			break;
+		case '5': /* filter */
+			if (params->events) {
+				retval = trace_event_add_filter(params->events, optarg);
+				if (retval) {
+					err_msg("Error adding filter %s\n", optarg);
+					exit(EXIT_FAILURE);
+				}
+			} else {
+				osnoise_hist_usage("--filter requires a previous -e\n");
+			}
 			break;
 		default:
 			osnoise_hist_usage("Invalid option");
···
 		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->threshold) {
+		retval = osnoise_set_tracing_thresh(tool->context, params->threshold);
+		if (retval) {
+			err_msg("Failed to set tracing_thresh\n");
 			goto out_err;
 		}
 	}
···
 			err_msg("Failed to enable the trace instance\n");
 			goto out_hist;
 		}
+
+		if (params->events) {
+			retval = trace_events_enable(&record->trace, params->events);
+			if (retval)
+				goto out_hist;
+		}
+
 		trace_instance_start(&record->trace);
 	}
 
···
 			goto out_hist;
 		}
 
-		if (!tracefs_trace_is_on(trace->inst))
+		if (trace_is_off(&tool->trace, &record->trace))
 			break;
-	};
+	}
 
 	osnoise_read_trace_hist(tool);
 
···
 
 	return_value = 0;
 
-	if (!tracefs_trace_is_on(trace->inst)) {
-		printf("rtla timelat hit stop tracing\n");
+	if (trace_is_off(&tool->trace, &record->trace)) {
+		printf("rtla 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_hist:
+	trace_events_destroy(&record->trace, params->events);
+	params->events = NULL;
 	osnoise_free_histogram(tool->data);
 out_destroy:
 	osnoise_destroy_tool(record);

tools/tracing/rtla/src/osnoise_top.c

···
 	char			*trace_output;
 	unsigned long long	runtime;
 	unsigned long long	period;
+	long long		threshold;
 	long long		stop_us;
 	long long		stop_total_us;
 	int			sleep_time;
···
 	int			quiet;
 	int			set_sched;
 	struct sched_attr	sched_param;
+	struct trace_events	*events;
 };
 
 struct osnoise_top_cpu {
···
 	int i;
 
 	static const char * const msg[] = {
-		"  usage: rtla osnoise [top] [-h] [-q] [-D] [-d s] [-p us] [-r us] [-s us] [-S us] [-t[=file]] \\",
+		"  usage: rtla osnoise [top] [-h] [-q] [-D] [-d s] [-a us] [-p us] [-r us] [-s us] [-S us] \\",
+		"	  [-T us] [-t[=file]] [-e sys[:event]] [--filter <filter>] [--trigger <trigger>] \\",
 		"	  [-c cpu-list] [-P priority]",
 		"",
 		"	  -h/--help: print this menu",
+		"	  -a/--auto: set automatic trace mode, stopping the session if argument in us sample is hit",
 		"	  -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",
+		"	  -T/--threshold us: the minimum delta to be considered a noise",
 		"	  -c/--cpus cpu-list: list of cpus to run osnoise threads",
 		"	  -d/--duration time[s|m|h|d]: duration of the session",
 		"	  -D/--debug: print debug info",
 		"	  -t/--trace[=file]: save the stopped trace to [file|osnoise_trace.txt]",
+		"	  -e/--event <sys:event>: enable the <sys:event> in the trace instance, multiple -e are allowed",
+		"	     --filter <filter>: enable a trace event filter to the previous -e event",
+		"	     --trigger <trigger>: enable a trace event trigger to the previous -e event",
 		"	  -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",
···
 struct osnoise_top_params *osnoise_top_parse_args(int argc, char **argv)
 {
 	struct osnoise_top_params *params;
+	struct trace_events *tevent;
 	int retval;
 	int c;
 
···
 
 	while (1) {
 		static struct option long_options[] = {
+			{"auto",		required_argument,	0, 'a'},
 			{"cpus",		required_argument,	0, 'c'},
 			{"debug",		no_argument,		0, 'D'},
 			{"duration",		required_argument,	0, 'd'},
+			{"event",		required_argument,	0, 'e'},
 			{"help",		no_argument,		0, 'h'},
 			{"period",		required_argument,	0, 'p'},
 			{"priority",		required_argument,	0, 'P'},
···
 			{"runtime",		required_argument,	0, 'r'},
 			{"stop",		required_argument,	0, 's'},
 			{"stop-total",		required_argument,	0, 'S'},
+			{"threshold",		required_argument,	0, 'T'},
 			{"trace",		optional_argument,	0, 't'},
+			{"trigger",		required_argument,	0, '0'},
+			{"filter",		required_argument,	0, '1'},
 			{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::",
+		c = getopt_long(argc, argv, "a:c:d:De:hp:P:qr:s:S:t::T:0:1:",
 				 long_options, &option_index);
 
 		/* Detect the end of the options. */
···
 			break;
 
 		switch (c) {
+		case 'a':
+			/* set sample stop to auto_thresh */
+			params->stop_us = get_llong_from_str(optarg);
+
+			/* set sample threshold to 1 */
+			params->threshold = 1;
+
+			/* set trace */
+			params->trace_output = "osnoise_trace.txt";
+
+			break;
 		case 'c':
 			retval = parse_cpu_list(optarg, &params->monitored_cpus);
 			if (retval)
···
 			params->duration = parse_seconds_duration(optarg);
 			if (!params->duration)
 				osnoise_top_usage("Invalid -D duration\n");
+			break;
+		case 'e':
+			tevent = trace_event_alloc(optarg);
+			if (!tevent) {
+				err_msg("Error alloc trace event");
+				exit(EXIT_FAILURE);
+			}
+
+			if (params->events)
+				tevent->next = params->events;
+			params->events = tevent;
+
 			break;
 		case 'h':
 		case '?':
···
 				params->trace_output = &optarg[1];
 			else
 				params->trace_output = "osnoise_trace.txt";
+			break;
+		case 'T':
+			params->threshold = get_llong_from_str(optarg);
+			break;
+		case '0': /* trigger */
+			if (params->events) {
+				retval = trace_event_add_trigger(params->events, optarg);
+				if (retval) {
+					err_msg("Error adding trigger %s\n", optarg);
+					exit(EXIT_FAILURE);
+				}
+			} else {
+				osnoise_top_usage("--trigger requires a previous -e\n");
+			}
+			break;
+		case '1': /* filter */
+			if (params->events) {
+				retval = trace_event_add_filter(params->events, optarg);
+				if (retval) {
+					err_msg("Error adding filter %s\n", optarg);
+					exit(EXIT_FAILURE);
+				}
+			} else {
+				osnoise_top_usage("--filter requires a previous -e\n");
+			}
 			break;
 		default:
 			osnoise_top_usage("Invalid option");
···
 		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->threshold) {
+		retval = osnoise_set_tracing_thresh(tool->context, params->threshold);
+		if (retval) {
+			err_msg("Failed to set tracing_thresh\n");
 			goto out_err;
 		}
 	}
···
 			err_msg("Failed to enable the trace instance\n");
 			goto out_top;
 		}
+
+		if (params->events) {
+			retval = trace_events_enable(&record->trace, params->events);
+			if (retval)
+				goto out_top;
+		}
+
 		trace_instance_start(&record->trace);
 	}
 
 	tool->start_time = time(NULL);
 	osnoise_top_set_signals(params);
 
-	do {
+	while (!stop_tracing) {
 		sleep(params->sleep_time);
 
 		retval = tracefs_iterate_raw_events(trace->tep,
···
 		if (!params->quiet)
 			osnoise_print_stats(params, tool);
 
-		if (!tracefs_trace_is_on(trace->inst))
+		if (trace_is_off(&tool->trace, &record->trace))
 			break;
 
-	} while (!stop_tracing);
+	}
 
 	osnoise_print_stats(params, tool);
 
 	return_value = 0;
 
-	if (!tracefs_trace_is_on(trace->inst)) {
+	if (trace_is_off(&tool->trace, &record->trace)) {
 		printf("osnoise hit stop tracing\n");
 		if (params->trace_output) {
 			printf("  Saving trace to %s\n", params->trace_output);
···
 	}
 
 out_top:
+	trace_events_destroy(&record->trace, params->events);
+	params->events = NULL;
 	osnoise_free_top(tool->data);
 	osnoise_destroy_tool(record);
 	osnoise_destroy_tool(tool);

tools/tracing/rtla/src/timerlat_hist.c

···
 	int			output_divisor;
 	int			duration;
 	int			set_sched;
+	int			dma_latency;
 	struct sched_attr	sched_param;
+	struct trace_events	*events;
 
 	char			no_irq;
 	char			no_thread;
···
 
 	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]",
+		"  usage: [rtla] timerlat hist [-h] [-q] [-d s] [-D] [-n] [-a us] [-p us] [-i us] [-T us] [-s us] \\",
+		"         [-t[=file]] [-e sys[:event]] [--filter <filter>] [--trigger <trigger>] [-c cpu-list] \\",
+		"	  [-P priority] [-E N] [-b N] [--no-irq] [--no-thread] [--no-header] [--no-summary] \\",
+		"	  [--no-index] [--with-zeros] [--dma-latency us]",
 		"",
 		"	  -h/--help: print this menu",
+		"	  -a/--auto: set automatic trace mode, stopping the session if argument in us latency is hit",
 		"	  -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",
···
 		"	  -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]",
+		"	  -t/--trace[=file]: save the stopped trace to [file|timerlat_trace.txt]",
+		"	  -e/--event <sys:event>: enable the <sys:event> in the trace instance, multiple -e are allowed",
+		"	     --filter <filter>: enable a trace event filter to the previous -e event",
+		"	     --trigger <trigger>: enable a trace event trigger to the previous -e event",
 		"	  -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-summary: do not print summary",
 		"	     --no-index: do not print index",
 		"	     --with-zeros: print zero only entries",
+		"	     --dma-latency us: set /dev/cpu_dma_latency latency <us> to reduce exit from idle latency",
 		"	  -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",
···
 *timerlat_hist_parse_args(int argc, char *argv[])
 {
 	struct timerlat_hist_params *params;
+	struct trace_events *tevent;
+	int auto_thresh;
 	int retval;
 	int c;
 
 	params = calloc(1, sizeof(*params));
 	if (!params)
 		exit(1);
+
+	/* disabled by default */
+	params->dma_latency = -1;
 
 	/* display data in microseconds */
 	params->output_divisor = 1000;
···
 
 	while (1) {
 		static struct option long_options[] = {
+			{"auto",		required_argument,	0, 'a'},
 			{"cpus",		required_argument,	0, 'c'},
 			{"bucket-size",		required_argument,	0, 'b'},
 			{"debug",		no_argument,		0, 'D'},
···
 			{"stack",		required_argument,	0, 's'},
 			{"thread",		required_argument,	0, 'T'},
 			{"trace",		optional_argument,	0, 't'},
+			{"event",		required_argument,	0, 'e'},
 			{"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'},
+			{"trigger",		required_argument,	0, '6'},
+			{"filter",		required_argument,	0, '7'},
+			{"dma-latency",		required_argument,	0, '8'},
 			{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",
+		c = getopt_long(argc, argv, "a:c:b:d:e:E:Dhi:np:P:s:t::T:0123456:7:8:",
 				 long_options, &option_index);
 
 		/* detect the end of the options. */
···
 			break;
 
 		switch (c) {
+		case 'a':
+			auto_thresh = get_llong_from_str(optarg);
+
+			/* set thread stop to auto_thresh */
+			params->stop_total_us = auto_thresh;
+
+			/* get stack trace */
+			params->print_stack = auto_thresh;
+
+			/* set trace */
+			params->trace_output = "timerlat_trace.txt";
+
+			break;
 		case 'c':
 			retval = parse_cpu_list(optarg, &params->monitored_cpus);
 			if (retval)
···
 			params->duration = parse_seconds_duration(optarg);
 			if (!params->duration)
 				timerlat_hist_usage("Invalid -D duration\n");
+			break;
+		case 'e':
+			tevent = trace_event_alloc(optarg);
+			if (!tevent) {
+				err_msg("Error alloc trace event");
+				exit(EXIT_FAILURE);
+			}
+
+			if (params->events)
+				tevent->next = params->events;
+
+			params->events = tevent;
 			break;
 		case 'E':
 			params->entries = get_llong_from_str(optarg);
···
 			break;
 		case '5': /* with zeros */
 			params->with_zeros = 1;
+			break;
+		case '6': /* trigger */
+			if (params->events) {
+				retval = trace_event_add_trigger(params->events, optarg);
+				if (retval) {
+					err_msg("Error adding trigger %s\n", optarg);
+					exit(EXIT_FAILURE);
+				}
+			} else {
+				timerlat_hist_usage("--trigger requires a previous -e\n");
+			}
+			break;
+		case '7': /* filter */
+			if (params->events) {
+				retval = trace_event_add_filter(params->events, optarg);
+				if (retval) {
+					err_msg("Error adding filter %s\n", optarg);
+					exit(EXIT_FAILURE);
+				}
+			} else {
+				timerlat_hist_usage("--filter requires a previous -e\n");
+			}
+			break;
+		case '8':
+			params->dma_latency = get_llong_from_str(optarg);
+			if (params->dma_latency < 0 || params->dma_latency > 10000) {
+				err_msg("--dma-latency needs to be >= 0 and < 10000");
+				exit(EXIT_FAILURE);
+			}
 			break;
 		default:
 			timerlat_hist_usage("Invalid option");
···
 	struct osnoise_tool *record = NULL;
 	struct osnoise_tool *tool = NULL;
 	struct trace_instance *trace;
+	int dma_latency_fd = -1;
 	int return_value = 1;
 	int retval;
 
···
 		}
 	}
 
+	if (params->dma_latency >= 0) {
+		dma_latency_fd = set_cpu_dma_latency(params->dma_latency);
+		if (dma_latency_fd < 0) {
+			err_msg("Could not set /dev/cpu_dma_latency.\n");
+			goto out_hist;
+		}
+	}
+
 	trace_instance_start(trace);
 
 	if (params->trace_output) {
···
 			err_msg("Failed to enable the trace instance\n");
 			goto out_hist;
 		}
+
+		if (params->events) {
+			retval = trace_events_enable(&record->trace, params->events);
+			if (retval)
+				goto out_hist;
+		}
+
 		trace_instance_start(&record->trace);
 	}
 
···
 			goto out_hist;
 		}
 
-		if (!tracefs_trace_is_on(trace->inst))
+		if (trace_is_off(&tool->trace, &record->trace))
 			break;
-	};
+	}
 
 	timerlat_print_stats(params, tool);
 
 	return_value = 0;
 
-	if (!tracefs_trace_is_on(trace->inst)) {
+	if (trace_is_off(&tool->trace, &record->trace)) {
 		printf("rtla timelat hit stop tracing\n");
 		if (params->trace_output) {
 			printf("  Saving trace to %s\n", params->trace_output);
···
 	}
 
 out_hist:
+	if (dma_latency_fd >= 0)
+		close(dma_latency_fd);
+	trace_events_destroy(&record->trace, params->events);
+	params->events = NULL;
 	timerlat_free_histogram(tool->data);
 	osnoise_destroy_tool(record);
 	osnoise_destroy_tool(tool);

tools/tracing/rtla/src/timerlat_top.c

···
 	int			duration;
 	int			quiet;
 	int			set_sched;
+	int			dma_latency;
 	struct sched_attr	sched_param;
+	struct trace_events	*events;
 };
 
 struct timerlat_top_cpu {
···
 
 	static const char *const msg[] = {
 		"",
-		"  usage: rtla timerlat [top] [-h] [-q] [-d s] [-D] [-n] [-p us] [-i us] [-T us] [-s us] [-t[=file]] \\",
-		"	  [-c cpu-list] [-P priority]",
+		"  usage: rtla timerlat [top] [-h] [-q] [-a us] [-d s] [-D] [-n] [-p us] [-i us] [-T us] [-s us] \\",
+		"	  [[-t[=file]] [-e sys[:event]] [--filter <filter>] [--trigger <trigger>] [-c cpu-list] \\",
+		"	  [-P priority] [--dma-latency us]",
 		"",
 		"	  -h/--help: print this menu",
+		"	  -a/--auto: set automatic trace mode, stopping the session if argument in us latency is hit",
 		"	  -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",
···
 		"	  -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]",
+		"	  -e/--event <sys:event>: enable the <sys:event> in the trace instance, multiple -e are allowed",
+		"	     --filter <command>: enable a trace event filter to the previous -e event",
+		"	     --trigger <command>: enable a trace event trigger to the previous -e event",
 		"	  -n/--nano: display data in nanoseconds",
 		"	  -q/--quiet print only a summary at the end",
+		"	     --dma-latency us: set /dev/cpu_dma_latency latency <us> to reduce exit from idle latency",
 		"	  -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",
···
 *timerlat_top_parse_args(int argc, char **argv)
 {
 	struct timerlat_top_params *params;
+	struct trace_events *tevent;
+	long long auto_thresh;
 	int retval;
 	int c;
 
···
 	if (!params)
 		exit(1);
 
+	/* disabled by default */
+	params->dma_latency = -1;
+
 	/* display data in microseconds */
 	params->output_divisor = 1000;
 
 	while (1) {
 		static struct option long_options[] = {
+			{"auto",		required_argument,	0, 'a'},
 			{"cpus",		required_argument,	0, 'c'},
 			{"debug",		no_argument,		0, 'D'},
 			{"duration",		required_argument,	0, 'd'},
+			{"event",		required_argument,	0, 'e'},
 			{"help",		no_argument,		0, 'h'},
 			{"irq",			required_argument,	0, 'i'},
 			{"nano",		no_argument,		0, 'n'},
···
 			{"stack",		required_argument,	0, 's'},
 			{"thread",		required_argument,	0, 'T'},
 			{"trace",		optional_argument,	0, 't'},
+			{"trigger",		required_argument,	0, '0'},
+			{"filter",		required_argument,	0, '1'},
+			{"dma-latency",		required_argument,	0, '2'},
 			{0, 0, 0, 0}
 		};
 
 		/* getopt_long stores the option index here. */
 		int option_index = 0;
 
-		c = getopt_long(argc, argv, "c:d:Dhi:np:P:qs:t::T:",
+		c = getopt_long(argc, argv, "a:c:d:De:hi:np:P:qs:t::T:0:1:2:",
 				 long_options, &option_index);
 
 		/* detect the end of the options. */
···
 			break;
 
 		switch (c) {
+		case 'a':
+			auto_thresh = get_llong_from_str(optarg);
+
+			/* set thread stop to auto_thresh */
+			params->stop_total_us = auto_thresh;
+
+			/* get stack trace */
+			params->print_stack = auto_thresh;
+
+			/* set trace */
+			params->trace_output = "timerlat_trace.txt";
+
+			break;
 		case 'c':
 			retval = parse_cpu_list(optarg, &params->monitored_cpus);
 			if (retval)
···
 			params->duration = parse_seconds_duration(optarg);
 			if (!params->duration)
 				timerlat_top_usage("Invalid -D duration\n");
+			break;
+		case 'e':
+			tevent = trace_event_alloc(optarg);
+			if (!tevent) {
+				err_msg("Error alloc trace event");
+				exit(EXIT_FAILURE);
+			}
+
+			if (params->events)
+				tevent->next = params->events;
+			params->events = tevent;
 			break;
 		case 'h':
 		case '?':
···
 				params->trace_output = &optarg[1];
 			else
 				params->trace_output = "timerlat_trace.txt";
+			break;
+		case '0': /* trigger */
+			if (params->events) {
+				retval = trace_event_add_trigger(params->events, optarg);
+				if (retval) {
+					err_msg("Error adding trigger %s\n", optarg);
+					exit(EXIT_FAILURE);
+				}
+			} else {
+				timerlat_top_usage("--trigger requires a previous -e\n");
+			}
+			break;
+		case '1': /* filter */
+			if (params->events) {
+				retval = trace_event_add_filter(params->events, optarg);
+				if (retval) {
+					err_msg("Error adding filter %s\n", optarg);
+					exit(EXIT_FAILURE);
+				}
+			} else {
+				timerlat_top_usage("--filter requires a previous -e\n");
+			}
+			break;
+		case '2': /* dma-latency */
+			params->dma_latency = get_llong_from_str(optarg);
+			if (params->dma_latency < 0 || params->dma_latency > 10000) {
+				err_msg("--dma-latency needs to be >= 0 and < 10000");
+				exit(EXIT_FAILURE);
+			}
 			break;
 		default:
 			timerlat_top_usage("Invalid option");
···
 	struct osnoise_tool *record = NULL;
 	struct osnoise_tool *top = NULL;
 	struct trace_instance *trace;
+	int dma_latency_fd = -1;
 	int return_value = 1;
 	int retval;
 
···
 		}
 	}
 
+	if (params->dma_latency >= 0) {
+		dma_latency_fd = set_cpu_dma_latency(params->dma_latency);
+		if (dma_latency_fd < 0) {
+			err_msg("Could not set /dev/cpu_dma_latency.\n");
+			goto out_top;
+		}
+	}
+
 	trace_instance_start(trace);
 
 	if (params->trace_output) {
···
 			err_msg("Failed to enable the trace instance\n");
 			goto out_top;
 		}
+
+		if (params->events) {
+			retval = trace_events_enable(&record->trace, params->events);
+			if (retval)
+				goto out_top;
+		}
+
 		trace_instance_start(&record->trace);
 	}
 
···
 		if (!params->quiet)
 			timerlat_print_stats(params, top);
 
-		if (!tracefs_trace_is_on(trace->inst))
+		if (trace_is_off(&top->trace, &record->trace))
 			break;
 
-	};
+	}
 
 	timerlat_print_stats(params, top);
 
 	return_value = 0;
 
-	if (!tracefs_trace_is_on(trace->inst)) {
+	if (trace_is_off(&top->trace, &record->trace)) {
 		printf("rtla timelat hit stop tracing\n");
 		if (params->trace_output) {
 			printf("  Saving trace to %s\n", params->trace_output);
···
 	}
 
 out_top:
+	if (dma_latency_fd >= 0)
+		close(dma_latency_fd);
+	trace_events_destroy(&record->trace, params->events);
+	params->events = NULL;
 	timerlat_free_top(top->data);
 	osnoise_destroy_tool(record);
 	osnoise_destroy_tool(top);

tools/tracing/rtla/src/trace.c

···
 {
 	return tracefs_trace_on(trace->inst);
 }
+
+/*
+ * trace_events_free - free a list of trace events
+ */
+static void trace_events_free(struct trace_events *events)
+{
+	struct trace_events *tevent = events;
+	struct trace_events *free_event;
+
+	while (tevent) {
+		free_event = tevent;
+
+		tevent = tevent->next;
+
+		if (free_event->filter)
+			free(free_event->filter);
+		if (free_event->trigger)
+			free(free_event->trigger);
+		free(free_event->system);
+		free(free_event);
+	}
+}
+
+/*
+ * trace_event_alloc - alloc and parse a single trace event
+ */
+struct trace_events *trace_event_alloc(const char *event_string)
+{
+	struct trace_events *tevent;
+
+	tevent = calloc(1, sizeof(*tevent));
+	if (!tevent)
+		return NULL;
+
+	tevent->system = strdup(event_string);
+	if (!tevent->system) {
+		free(tevent);
+		return NULL;
+	}
+
+	tevent->event = strstr(tevent->system, ":");
+	if (tevent->event) {
+		*tevent->event = '\0';
+		tevent->event = &tevent->event[1];
+	}
+
+	return tevent;
+}
+
+/*
+ * trace_event_add_filter - record an event filter
+ */
+int trace_event_add_filter(struct trace_events *event, char *filter)
+{
+	if (event->filter)
+		free(event->filter);
+
+	event->filter = strdup(filter);
+	if (!event->filter)
+		return 1;
+
+	return 0;
+}
+
+/*
+ * trace_event_add_trigger - record an event trigger action
+ */
+int trace_event_add_trigger(struct trace_events *event, char *trigger)
+{
+	if (event->trigger)
+		free(event->trigger);
+
+	event->trigger = strdup(trigger);
+	if (!event->trigger)
+		return 1;
+
+	return 0;
+}
+
+/*
+ * trace_event_disable_filter - disable an event filter
+ */
+static void trace_event_disable_filter(struct trace_instance *instance,
+				       struct trace_events *tevent)
+{
+	char filter[1024];
+	int retval;
+
+	if (!tevent->filter)
+		return;
+
+	if (!tevent->filter_enabled)
+		return;
+
+	debug_msg("Disabling %s:%s filter %s\n", tevent->system,
+		  tevent->event ? : "*", tevent->filter);
+
+	snprintf(filter, 1024, "!%s\n", tevent->filter);
+
+	retval = tracefs_event_file_write(instance->inst, tevent->system,
+					  tevent->event, "filter", filter);
+	if (retval < 0)
+		err_msg("Error disabling %s:%s filter %s\n", tevent->system,
+			tevent->event ? : "*", tevent->filter);
+}
+
+/*
+ * trace_event_save_hist - save the content of an event hist
+ *
+ * If the trigger is a hist: one, save the content of the hist file.
+ */
+static void trace_event_save_hist(struct trace_instance *instance,
+				  struct trace_events *tevent)
+{
+	int retval, index, out_fd;
+	mode_t mode = 0644;
+	char path[1024];
+	char *hist;
+
+	if (!tevent)
+		return;
+
+	/* trigger enables hist */
+	if (!tevent->trigger)
+		return;
+
+	/* is this a hist: trigger? */
+	retval = strncmp(tevent->trigger, "hist:", strlen("hist:"));
+	if (retval)
+		return;
+
+	snprintf(path, 1024, "%s_%s_hist.txt", tevent->system, tevent->event);
+
+	printf("  Saving event %s:%s hist to %s\n", tevent->system, tevent->event, path);
+
+	out_fd = creat(path, mode);
+	if (out_fd < 0) {
+		err_msg("  Failed to create %s output file\n", path);
+		return;
+	}
+
+	hist = tracefs_event_file_read(instance->inst, tevent->system, tevent->event, "hist", 0);
+	if (!hist) {
+		err_msg("  Failed to read %s:%s hist file\n", tevent->system, tevent->event);
+		goto out_close;
+	}
+
+	index = 0;
+	do {
+		index += write(out_fd, &hist[index], strlen(hist) - index);
+	} while (index < strlen(hist));
+
+	free(hist);
+out_close:
+	close(out_fd);
+}
+
+/*
+ * trace_event_disable_trigger - disable an event trigger
+ */
+static void trace_event_disable_trigger(struct trace_instance *instance,
+					struct trace_events *tevent)
+{
+	char trigger[1024];
+	int retval;
+
+	if (!tevent->trigger)
+		return;
+
+	if (!tevent->trigger_enabled)
+		return;
+
+	debug_msg("Disabling %s:%s trigger %s\n", tevent->system,
+		  tevent->event ? : "*", tevent->trigger);
+
+	trace_event_save_hist(instance, tevent);
+
+	snprintf(trigger, 1024, "!%s\n", tevent->trigger);
+
+	retval = tracefs_event_file_write(instance->inst, tevent->system,
+					  tevent->event, "trigger", trigger);
+	if (retval < 0)
+		err_msg("Error disabling %s:%s trigger %s\n", tevent->system,
+			tevent->event ? : "*", tevent->trigger);
+}
+
+/*
+ * trace_events_disable - disable all trace events
+ */
+void trace_events_disable(struct trace_instance *instance,
+			  struct trace_events *events)
+{
+	struct trace_events *tevent = events;
+
+	if (!events)
+		return;
+
+	while (tevent) {
+		debug_msg("Disabling event %s:%s\n", tevent->system, tevent->event ? : "*");
+		if (tevent->enabled) {
+			trace_event_disable_filter(instance, tevent);
+			trace_event_disable_trigger(instance, tevent);
+			tracefs_event_disable(instance->inst, tevent->system, tevent->event);
+		}
+
+		tevent->enabled = 0;
+		tevent = tevent->next;
+	}
+}
+
+/*
+ * trace_event_enable_filter - enable an event filter associated with an event
+ */
+static int trace_event_enable_filter(struct trace_instance *instance,
+				     struct trace_events *tevent)
+{
+	char filter[1024];
+	int retval;
+
+	if (!tevent->filter)
+		return 0;
+
+	if (!tevent->event) {
+		err_msg("Filter %s applies only for single events, not for all %s:* events\n",
+			tevent->filter, tevent->system);
+		return 1;
+	}
+
+	snprintf(filter, 1024, "%s\n", tevent->filter);
+
+	debug_msg("Enabling %s:%s filter %s\n", tevent->system,
+		  tevent->event ? : "*", tevent->filter);
+
+	retval = tracefs_event_file_write(instance->inst, tevent->system,
+					  tevent->event, "filter", filter);
+	if (retval < 0) {
+		err_msg("Error enabling %s:%s filter %s\n", tevent->system,
+			tevent->event ? : "*", tevent->filter);
+		return 1;
+	}
+
+	tevent->filter_enabled = 1;
+	return 0;
+}
+
+/*
+ * trace_event_enable_trigger - enable an event trigger associated with an event
+ */
+static int trace_event_enable_trigger(struct trace_instance *instance,
+				      struct trace_events *tevent)
+{
+	char trigger[1024];
+	int retval;
+
+	if (!tevent->trigger)
+		return 0;
+
+	if (!tevent->event) {
+		err_msg("Trigger %s applies only for single events, not for all %s:* events\n",
+			tevent->trigger, tevent->system);
+		return 1;
+	}
+
+	snprintf(trigger, 1024, "%s\n", tevent->trigger);
+
+	debug_msg("Enabling %s:%s trigger %s\n", tevent->system,
+		  tevent->event ? : "*", tevent->trigger);
+
+	retval = tracefs_event_file_write(instance->inst, tevent->system,
+					  tevent->event, "trigger", trigger);
+	if (retval < 0) {
+		err_msg("Error enabling %s:%s trigger %s\n", tevent->system,
+			tevent->event ? : "*", tevent->trigger);
+		return 1;
+	}
+
+	tevent->trigger_enabled = 1;
+
+	return 0;
+}
+
+/*
+ * trace_events_enable - enable all events
+ */
+int trace_events_enable(struct trace_instance *instance,
+			struct trace_events *events)
+{
+	struct trace_events *tevent = events;
+	int retval;
+
+	while (tevent) {
+		debug_msg("Enabling event %s:%s\n", tevent->system, tevent->event ? : "*");
+		retval = tracefs_event_enable(instance->inst, tevent->system, tevent->event);
+		if (retval < 0) {
+			err_msg("Error enabling event %s:%s\n", tevent->system,
+				tevent->event ? : "*");
+			return 1;
+		}
+
+		retval = trace_event_enable_filter(instance, tevent);
+		if (retval)
+			return 1;
+
+		retval = trace_event_enable_trigger(instance, tevent);
+		if (retval)
+			return 1;
+
+		tevent->enabled = 1;
+		tevent = tevent->next;
+	}
+
+	return 0;
+}
+
+/*
+ * trace_events_destroy - disable and free all trace events
+ */
+void trace_events_destroy(struct trace_instance *instance,
+			  struct trace_events *events)
+{
+	if (!events)
+		return;
+
+	trace_events_disable(instance, events);
+	trace_events_free(events);
+}
+
+int trace_is_off(struct trace_instance *tool, struct trace_instance *trace)
+{
+	/*
+	 * The tool instance is always present, it is the one used to collect
+	 * data.
+	 */
+	if (!tracefs_trace_is_on(tool->inst))
+		return 1;
+
+	/*
+	 * The trace instance is only enabled when -t is set. IOW, when the system
+	 * is tracing.
+	 */
+	if (trace && !tracefs_trace_is_on(trace->inst))
+		return 1;
+
+	return 0;
+}

tools/tracing/rtla/src/trace.h

···
 #include <tracefs.h>
 #include <stddef.h>
 
+struct trace_events {
+	struct trace_events *next;
+	char *system;
+	char *event;
+	char *filter;
+	char *trigger;
+	char enabled;
+	char filter_enabled;
+	char trigger_enabled;
+};
+
 struct trace_instance {
 	struct tracefs_instance		*inst;
 	struct tep_handle		*tep;
···
 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);
+
+struct trace_events *trace_event_alloc(const char *event_string);
+void trace_events_disable(struct trace_instance *instance,
+			  struct trace_events *events);
+void trace_events_destroy(struct trace_instance *instance,
+			  struct trace_events *events);
+int trace_events_enable(struct trace_instance *instance,
+			  struct trace_events *events);
+
+int trace_event_add_filter(struct trace_events *event, char *filter);
+int trace_event_add_trigger(struct trace_events *event, char *trigger);
+int trace_is_off(struct trace_instance *tool, struct trace_instance *trace);

tools/tracing/rtla/src/utils.c

···
 #include <unistd.h>
 #include <ctype.h>
 #include <errno.h>
+#include <fcntl.h>
 #include <sched.h>
 #include <stdio.h>
 
···
 		return -1;
 	}
 	return 0;
+}
+
+/*
+ * set_cpu_dma_latency - set the /dev/cpu_dma_latecy
+ *
+ * This is used to reduce the exit from idle latency. The value
+ * will be reset once the file descriptor of /dev/cpu_dma_latecy
+ * is closed.
+ *
+ * Return: the /dev/cpu_dma_latecy file descriptor
+ */
+int set_cpu_dma_latency(int32_t latency)
+{
+	int retval;
+	int fd;
+
+	fd = open("/dev/cpu_dma_latency", O_RDWR);
+	if (fd < 0) {
+		err_msg("Error opening /dev/cpu_dma_latency\n");
+		return -1;
+	}
+
+	retval = write(fd, &latency, 4);
+	if (retval < 1) {
+		err_msg("Error setting /dev/cpu_dma_latency\n");
+		close(fd);
+		return -1;
+	}
+
+	debug_msg("Set /dev/cpu_dma_latency to %d\n", latency);
+
+	return fd;
 }

tools/tracing/rtla/src/utils.h

···
 
 int parse_prio(char *arg, struct sched_attr *sched_param);
 int set_comm_sched_attr(const char *comm, struct sched_attr *attr);
+int set_cpu_dma_latency(int32_t latency);