rtla: Add --trigger support

Add --trigger option. This option enables a trace event trigger to the
previous -e sys:event argument, allowing some advanced tracing options.

For instance, in a system with CPUs 2:23 isolated, it is possible to get
a stack trace of thread wakeup targeting those CPUs while running
osnoise with the following command line:

 # osnoise top -c 2-23 -a 50 -e sched:sched_wakeup --trigger="stacktrace if target_cpu >= 2"

This option is available for all current tools.

Link: https://lkml.kernel.org/r/07d2983d5f71261d4da89dbaf02efcad100ab8ee.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>

1 files changed, 16 insertions, 3 deletions

diff --git a/tools/tracing/rtla/src/timerlat_hist.c b/tools/tracing/rtla/src/timerlat_hist.c
index 2bd668fd36f5..765b5a313bd2 100644
--- a/tools/tracing/rtla/src/timerlat_hist.c
+++ b/tools/tracing/rtla/src/timerlat_hist.c
@@ -430,8 +430,8 @@ static void timerlat_hist_usage(char *usage)
 	char *msg[] = {
 		"",
 		"  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]] [-c cpu-list] [-P priority] [-E N] [-b N] [--no-irq] \\",
-		"         [--no-thread] [--no-header] [--no-summary] [--no-index] [--with-zeros]",
+		"         [-t[=file]] [-e sys[:event]] [--trigger <trigger>] [-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",
@@ -444,6 +444,7 @@ static void timerlat_hist_usage(char *usage)
 		"	  -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",
+		"	     --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)",
@@ -517,13 +518,14 @@ static struct timerlat_hist_params
 			{"no-summary",		no_argument,		0, '3'},
 			{"no-index",		no_argument,		0, '4'},
 			{"with-zeros",		no_argument,		0, '5'},
+			{"trigger",		required_argument,	0, '6'},
 			{0, 0, 0, 0}
 		};
 
 		/* getopt_long stores the option index here. */
 		int option_index = 0;
 
-		c = getopt_long(argc, argv, "a:c:b:d:e: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:",
 				 long_options, &option_index);
 
 		/* detect the end of the options. */
@@ -632,6 +634,17 @@ static struct timerlat_hist_params
 		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;
 		default:
 			timerlat_hist_usage("Invalid option");
 		}