rtla/timerlat: Add the automatic trace option

Add the -a/--auto <arg in us> option. This option sets some commonly
used options while debugging the system. It aims to help users produce
reports in the field, reducing the number of arguments passed to the
tool in the first approach to a problem.

It is equivalent to setting osnoise/stop_tracing_total_us and print_stack
with the argument, and saving the trace to timerlat_trace.txt file if the
trace is stopped automatically.

Link: https://lkml.kernel.org/r/92438f7ef132c731f538cebdf77850300afe04a5.1646247211.git.bristot@kernel.org

Cc: Daniel Bristot de Oliveira <bristot@kernel.org>
Cc: Clark Williams <williams@redhat.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

Documentation/tools/rtla/common_timerlat_options.rst

@@ -1,3 +1,10 @@
+**-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.

tools/tracing/rtla/src/timerlat_hist.c

@@ -428,11 +428,12 @@ static void timerlat_hist_usage(char *usage)
 
 	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]] [-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",
+		"	  -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",
@@ -477,6 +478,7 @@ static struct timerlat_hist_params
 *timerlat_hist_parse_args(int argc, char *argv[])
 {
 	struct timerlat_hist_params *params;
+	int auto_thresh;
 	int retval;
 	int c;
 
@@ -491,6 +493,7 @@ static struct timerlat_hist_params
 
 	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'},
@@ -516,14 +519,27 @@ static struct timerlat_hist_params
 		/* 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:Dhi:np:P:s:t::T:012345",
 				 long_options, &option_index);
 
 		/* detect the end of the options. */
 		if (c == -1)
 			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)

tools/tracing/rtla/src/timerlat_top.c

@@ -266,10 +266,11 @@ static void timerlat_top_usage(char *usage)
 
 	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]] -c cpu-list] [-P priority]",
 		"",
 		"	  -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",
@@ -307,6 +308,7 @@ static struct timerlat_top_params
 *timerlat_top_parse_args(int argc, char **argv)
 {
 	struct timerlat_top_params *params;
+	long long auto_thresh;
 	int retval;
 	int c;
 
@@ -319,6 +321,7 @@ static struct timerlat_top_params
 
 	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'},
@@ -337,14 +340,27 @@ static struct timerlat_top_params
 		/* 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:Dhi:np:P:qs:t::T:",
 				 long_options, &option_index);
 
 		/* detect the end of the options. */
 		if (c == -1)
 			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)