rtla/timerlat: Add continue action

Introduce option to resume tracing after a latency threshold overflow.
The option is implemented as an action named "continue".

Example:
$ rtla timerlat top -q -T 200 -d 1s --on-threshold \
exec,command="echo Threshold" --on-threshold continue
Threshold
Threshold
Threshold
                                     Timer Latency
...

The feature is supported for both hist and top. After the continue
action is executed, processing of the list of actions is stopped and
tracing is resumed.

Cc: John Kacur <[email protected]>
Cc: Luis Goncalves <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Chang Yin <[email protected]>
Cc: Costa Shulyupin <[email protected]>
Cc: Crystal Wood <[email protected]>
Cc: Gabriele Monaco <[email protected]>
Link: https://lore.kernel.org/[email protected]
Signed-off-by: Tomas Glozar <[email protected]>
Signed-off-by: Steven Rostedt (Google) <[email protected]>

Author: lenticularis39

tools/tracing/rtla/src/actions.c

@@ -17,6 +17,7 @@ actions_init(struct actions *self)
 	self->size = action_default_size;
 	self->list = calloc(self->size, sizeof(struct action));
 	self->len = 0;
+	self->continue_flag = false;
 
 	memset(&self->present, 0, sizeof(self->present));
 
@@ -108,6 +109,20 @@ actions_add_shell(struct actions *self, const char *command)
 	return 0;
 }
 
+/*
+ * actions_add_continue - add an action to resume measurement
+ */
+int
+actions_add_continue(struct actions *self)
+{
+	struct action *action = actions_new(self);
+
+	self->present[ACTION_CONTINUE] = true;
+	action->type = ACTION_CONTINUE;
+
+	return 0;
+}
+
 /*
  * actions_parse - add an action based on text specification
  */
@@ -133,6 +148,8 @@ actions_parse(struct actions *self, const char *trigger)
 		type = ACTION_SIGNAL;
 	else if (strcmp(token, "shell") == 0)
 		type = ACTION_SHELL;
+	else if (strcmp(token, "continue") == 0)
+		type = ACTION_CONTINUE;
 	else
 		/* Invalid trigger type */
 		return -1;
@@ -187,6 +204,11 @@ actions_parse(struct actions *self, const char *trigger)
 		if (strlen(token) > 8 && strncmp(token, "command=", 8) == 0)
 			return actions_add_shell(self, token + 8);
 		return -1;
+	case ACTION_CONTINUE:
+		/* Takes no argument */
+		if (token != NULL)
+			return -1;
+		return actions_add_continue(self);
 	default:
 		return -1;
 	}
@@ -196,7 +218,7 @@ actions_parse(struct actions *self, const char *trigger)
  * actions_perform - perform all actions
  */
 int
-actions_perform(const struct actions *self)
+actions_perform(struct actions *self)
 {
 	int pid, retval;
 	const struct action *action;
@@ -226,6 +248,9 @@ actions_perform(const struct actions *self)
 			if (retval)
 				return retval;
 			break;
+		case ACTION_CONTINUE:
+			self->continue_flag = true;
+			return 0;
 		default:
 			break;
 		}

tools/tracing/rtla/src/actions.h

@@ -7,6 +7,7 @@ enum action_type {
 	ACTION_TRACE_OUTPUT,
 	ACTION_SIGNAL,
 	ACTION_SHELL,
+	ACTION_CONTINUE,
 	ACTION_FIELD_N
 };
 
@@ -35,6 +36,7 @@ struct actions {
 	struct action *list;
 	int len, size;
 	bool present[ACTION_FIELD_N];
+	bool continue_flag;
 
 	/* External dependencies */
 	struct tracefs_instance *trace_output_inst;
@@ -45,5 +47,6 @@ void actions_destroy(struct actions *self);
 int actions_add_trace_output(struct actions *self, const char *trace_output);
 int actions_add_signal(struct actions *self, int signal, int pid);
 int actions_add_shell(struct actions *self, const char *command);
+int actions_add_continue(struct actions *self);
 int actions_parse(struct actions *self, const char *trigger);
-int actions_perform(const struct actions *self);
+int actions_perform(struct actions *self);

tools/tracing/rtla/src/timerlat_hist.c

@@ -1374,8 +1374,20 @@ int timerlat_hist_main(int argc, char *argv[])
 				goto out_hist;
 			}
 
-			if (osnoise_trace_is_off(tool, record))
-				break;
+			if (osnoise_trace_is_off(tool, record)) {
+				actions_perform(&params->actions);
+
+				if (!params->actions.continue_flag)
+					/* continue flag not set, break */
+					break;
+
+				/* continue action reached, re-enable tracing */
+				if (params->actions.present[ACTION_TRACE_OUTPUT])
+					trace_instance_start(&record->trace);
+				if (!params->no_aa)
+					trace_instance_start(&aa->trace);
+				trace_instance_start(trace);
+			}
 
 			/* is there still any user-threads ? */
 			if (params->user_workload) {
@@ -1385,8 +1397,27 @@ int timerlat_hist_main(int argc, char *argv[])
 				}
 			}
 		}
-	} else
-		timerlat_bpf_wait(-1);
+	} else {
+		while (!stop_tracing) {
+			timerlat_bpf_wait(-1);
+
+			if (!stop_tracing) {
+				/* Threshold overflow, perform actions on threshold */
+				actions_perform(&params->actions);
+
+				if (!params->actions.continue_flag)
+					/* continue flag not set, break */
+					break;
+
+				/* continue action reached, re-enable tracing */
+				if (params->actions.present[ACTION_TRACE_OUTPUT])
+					trace_instance_start(&record->trace);
+				if (!params->no_aa)
+					trace_instance_start(&aa->trace);
+				timerlat_bpf_restart_tracing();
+			}
+		}
+	}
 
 	if (params->mode != TRACING_MODE_TRACEFS) {
 		timerlat_bpf_detach();
@@ -1412,7 +1443,6 @@ int timerlat_hist_main(int argc, char *argv[])
 		if (!params->no_aa)
 			timerlat_auto_analysis(params->stop_us, params->stop_total_us);
 
-		actions_perform(&params->actions);
 		return_value = FAILED;
 	}
 

tools/tracing/rtla/src/timerlat_top.c

@@ -906,6 +906,7 @@ timerlat_top_set_signals(struct timerlat_params *params)
 static int
 timerlat_top_main_loop(struct osnoise_tool *top,
 		       struct osnoise_tool *record,
+		       struct osnoise_tool *aa,
 		       struct timerlat_params *params,
 		       struct timerlat_u_params *params_u)
 {
@@ -932,8 +933,20 @@ timerlat_top_main_loop(struct osnoise_tool *top,
 		if (!params->quiet)
 			timerlat_print_stats(params, top);
 
-		if (osnoise_trace_is_off(top, record))
-			break;
+		if (osnoise_trace_is_off(top, record)) {
+			actions_perform(&params->actions);
+
+			if (!params->actions.continue_flag)
+				/* continue flag not set, break */
+				break;
+
+			/* continue action reached, re-enable tracing */
+			if (params->actions.present[ACTION_TRACE_OUTPUT])
+				trace_instance_start(&record->trace);
+			if (!params->no_aa)
+				trace_instance_start(&aa->trace);
+			trace_instance_start(trace);
+		}
 
 		/* is there still any user-threads ? */
 		if (params->user_workload) {
@@ -953,6 +966,7 @@ timerlat_top_main_loop(struct osnoise_tool *top,
 static int
 timerlat_top_bpf_main_loop(struct osnoise_tool *top,
 			   struct osnoise_tool *record,
+			   struct osnoise_tool *aa,
 			   struct timerlat_params *params,
 			   struct timerlat_u_params *params_u)
 {
@@ -964,34 +978,34 @@ timerlat_top_bpf_main_loop(struct osnoise_tool *top,
 		return 0;
 	}
 
-	if (params->quiet) {
-		/* Quiet mode: wait for stop and then, print results */
-		timerlat_bpf_wait(-1);
-
-		retval = timerlat_top_bpf_pull_data(top);
-		if (retval) {
-			err_msg("Error pulling BPF data\n");
-			return retval;
-		}
-
-		return 0;
-	}
-
 	/* Pull and display data in a loop */
 	while (!stop_tracing) {
-		wait_retval = timerlat_bpf_wait(params->sleep_time);
+		wait_retval = timerlat_bpf_wait(params->quiet ? -1 : params->sleep_time);
 
 		retval = timerlat_top_bpf_pull_data(top);
 		if (retval) {
 			err_msg("Error pulling BPF data\n");
 			return retval;
 		}
 
-		timerlat_print_stats(params, top);
+		if (!params->quiet)
+			timerlat_print_stats(params, top);
 
-		if (wait_retval == 1)
+		if (wait_retval == 1) {
 			/* Stopping requested by tracer */
-			break;
+			actions_perform(&params->actions);
+
+			if (!params->actions.continue_flag)
+				/* continue flag not set, break */
+				break;
+
+			/* continue action reached, re-enable tracing */
+			if (params->actions.present[ACTION_TRACE_OUTPUT])
+				trace_instance_start(&record->trace);
+			if (!params->no_aa)
+				trace_instance_start(&aa->trace);
+			timerlat_bpf_restart_tracing();
+		}
 
 		/* is there still any user-threads ? */
 		if (params->user_workload) {
@@ -1205,9 +1219,9 @@ int timerlat_top_main(int argc, char *argv[])
 	timerlat_top_set_signals(params);
 
 	if (params->mode == TRACING_MODE_TRACEFS)
-		retval = timerlat_top_main_loop(top, record, params, &params_u);
+		retval = timerlat_top_main_loop(top, record, aa, params, &params_u);
 	else
-		retval = timerlat_top_bpf_main_loop(top, record, params, &params_u);
+		retval = timerlat_top_bpf_main_loop(top, record, aa, params, &params_u);
 
 	if (retval)
 		goto out_top;
@@ -1230,7 +1244,6 @@ int timerlat_top_main(int argc, char *argv[])
 		if (!params->no_aa)
 			timerlat_auto_analysis(params->stop_us, params->stop_total_us);
 
-		actions_perform(&params->actions);
 		return_value = FAILED;
 	} else if (params->aa_only) {
 		/*