@@ -42,7 +42,7 @@
         - *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.
 
-**-C**, **--cgroup**\[*=cgroup*]
+**-C**, **--cgroup** \[*cgroup*]
 
         Set a *cgroup* to the tracer's threads. If the **-C** option is passed without arguments, the tracer's thread will inherit **rtla**'s *cgroup*. Otherwise, the threads will be placed on the *cgroup* passed to the option.
 

@@ -428,9 +428,9 @@ static void osnoise_hist_usage(char *usage)
 	static const char * const msg[] = {
 		"",
 		"  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>] \\",
+		"	  [-T us] [-t [file]] [-e sys[:event]] [--filter <filter>] [--trigger <trigger>] \\",
 		"	  [-c cpu-list] [-H cpu-list] [-P priority] [-b N] [-E N] [--no-header] [--no-summary] \\",
-		"	  [--no-index] [--with-zeros] [-C[=cgroup_name]] [--warm-up]",
+		"	  [--no-index] [--with-zeros] [-C [cgroup_name]] [--warm-up]",
 		"",
 		"	  -h/--help: print this menu",
 		"	  -a/--auto: set automatic trace mode, stopping the session if argument in us sample is hit",

@@ -441,10 +441,10 @@ static void osnoise_hist_usage(char *usage)
 		"	  -T/--threshold us: the minimum delta to be considered a noise",
 		"	  -c/--cpus cpu-list: list of cpus to run osnoise threads",
 		"	  -H/--house-keeping cpus: run rtla control threads only on the given cpus",
-		"	  -C/--cgroup[=cgroup_name]: set cgroup, if no cgroup_name is passed, the rtla's cgroup will be inherited",
+		"	  -C/--cgroup [cgroup_name]: set cgroup, if no cgroup_name is passed, the rtla's cgroup will be inherited",
 		"	  -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]",
+		"	  -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",

@@ -574,13 +574,7 @@ static struct common_params
 			break;
 		case 'C':
 			params->common.cgroup = 1;
-			if (!optarg) {
-				/* will inherit this cgroup */
-				params->common.cgroup_name = NULL;
-			} else if (*optarg == '=') {
-				/* skip the = */
-				params->common.cgroup_name = ++optarg;
-			}
+			params->common.cgroup_name = parse_optional_arg(argc, argv);
 			break;
 		case 'D':
 			config_debug = 1;

@@ -646,14 +640,8 @@ static struct common_params
 			params->threshold = get_llong_from_str(optarg);
 			break;
 		case 't':
-			if (optarg) {
-				if (optarg[0] == '=')
-					trace_output = &optarg[1];
-				else
-					trace_output = &optarg[0];
-			} else if (optind < argc && argv[optind][0] != '0')
-				trace_output = argv[optind];
-			else
+			trace_output = parse_optional_arg(argc, argv);
+			if (!trace_output)
 				trace_output = "osnoise_trace.txt";
 			break;
 		case '0': /* no header */

@@ -263,8 +263,8 @@ static void osnoise_top_usage(struct osnoise_params *params, char *usage)
 
 	static const char * const msg[] = {
 		" [-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] [-H cpu-list] [-P priority] [-C[=cgroup_name]] [--warm-up s]",
+		"	  [-T us] [-t [file]] [-e sys[:event]] [--filter <filter>] [--trigger <trigger>] \\",
+		"	  [-c cpu-list] [-H cpu-list] [-P priority] [-C [cgroup_name]] [--warm-up s]",
 		"",
 		"	  -h/--help: print this menu",
 		"	  -a/--auto: set automatic trace mode, stopping the session if argument in us sample is hit",

@@ -275,10 +275,10 @@ static void osnoise_top_usage(struct osnoise_params *params, char *usage)
 		"	  -T/--threshold us: the minimum delta to be considered a noise",
 		"	  -c/--cpus cpu-list: list of cpus to run osnoise threads",
 		"	  -H/--house-keeping cpus: run rtla control threads only on the given cpus",
-		"	  -C/--cgroup[=cgroup_name]: set cgroup, if no cgroup_name is passed, the rtla's cgroup will be inherited",
+		"	  -C/--cgroup [cgroup_name]: set cgroup, if no cgroup_name is passed, the rtla's cgroup will be inherited",
 		"	  -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]",
+		"	  -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",

@@ -408,13 +408,7 @@ struct common_params *osnoise_top_parse_args(int argc, char **argv)
 			break;
 		case 'C':
 			params->common.cgroup = 1;
-			if (!optarg) {
-				/* will inherit this cgroup */
-				params->common.cgroup_name = NULL;
-			} else if (*optarg == '=') {
-				/* skip the = */
-				params->common.cgroup_name = ++optarg;
-			}
+			params->common.cgroup_name = parse_optional_arg(argc, argv);
 			break;
 		case 'D':
 			config_debug = 1;

@@ -474,14 +468,8 @@ struct common_params *osnoise_top_parse_args(int argc, char **argv)
 			params->common.stop_total_us = get_llong_from_str(optarg);
 			break;
 		case 't':
-			if (optarg) {
-				if (optarg[0] == '=')
-					trace_output = &optarg[1];
-				else
-					trace_output = &optarg[0];
-			} else if (optind < argc && argv[optind][0] != '-')
-				trace_output = argv[optind];
-			else
+			trace_output = parse_optional_arg(argc, argv);
+			if (!trace_output)
 				trace_output = "osnoise_trace.txt";
 			break;
 		case 'T':

@@ -717,9 +717,9 @@ 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]] [--filter <filter>] [--trigger <trigger>] [-c cpu-list] [-H cpu-list]\\",
+		"         [-t [file]] [-e sys[:event]] [--filter <filter>] [--trigger <trigger>] [-c cpu-list] [-H cpu-list]\\",
 		"	  [-P priority] [-E N] [-b N] [--no-irq] [--no-thread] [--no-header] [--no-summary] \\",
-		"	  [--no-index] [--with-zeros] [--dma-latency us] [-C[=cgroup_name]] [--no-aa] [--dump-task] [-u|-k]",
+		"	  [--no-index] [--with-zeros] [--dma-latency us] [-C [cgroup_name]] [--no-aa] [--dump-task] [-u|-k]",
 		"	  [--warm-up s] [--deepest-idle-state n]",
 		"",
 		"	  -h/--help: print this menu",

@@ -730,11 +730,11 @@ static void timerlat_hist_usage(char *usage)
 		"	  -s/--stack us: save the stack trace at the IRQ if a thread latency is higher than the argument in us",
 		"	  -c/--cpus cpus: run the tracer only on the given cpus",
 		"	  -H/--house-keeping cpus: run rtla control threads only on the given cpus",
-		"	  -C/--cgroup[=cgroup_name]: set cgroup, if no cgroup_name is passed, the rtla's cgroup will be inherited",
+		"	  -C/--cgroup [cgroup_name]: set cgroup, if no cgroup_name is passed, the rtla's cgroup will be inherited",
 		"	  -d/--duration time[m|h|d]: duration of the session in seconds",
 		"	     --dump-tasks: prints the task running on all CPUs if stop conditions are met (depends on !--no-aa)",
 		"	  -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",

@@ -889,13 +889,7 @@ static struct common_params
 			break;
 		case 'C':
 			params->common.cgroup = 1;
-			if (!optarg) {
-				/* will inherit this cgroup */
-				params->common.cgroup_name = NULL;
-			} else if (*optarg == '=') {
-				/* skip the = */
-				params->common.cgroup_name = ++optarg;
-			}
+			params->common.cgroup_name = parse_optional_arg(argc, argv);
 			break;
 		case 'b':
 			params->common.hist.bucket_size = get_llong_from_str(optarg);

@@ -968,14 +962,8 @@ static struct common_params
 			params->common.stop_total_us = get_llong_from_str(optarg);
 			break;
 		case 't':
-			if (optarg) {
-				if (optarg[0] == '=')
-					trace_output = &optarg[1];
-				else
-					trace_output = &optarg[0];
-			} else if (optind < argc && argv[optind][0] != '-')
-				trace_output = argv[optind];
-			else
+			trace_output = parse_optional_arg(argc, argv);
+			if (!trace_output)
 				trace_output = "timerlat_trace.txt";
 			break;
 		case 'u':

@@ -483,8 +483,8 @@ static void timerlat_top_usage(char *usage)
 	static const char *const msg[] = {
 		"",
 		"  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] [-H cpu-list]\\",
-		"	  [-P priority] [--dma-latency us] [--aa-only us] [-C[=cgroup_name]] [-u|-k] [--warm-up s] [--deepest-idle-state n]",
+		"	  [[-t [file]] [-e sys[:event]] [--filter <filter>] [--trigger <trigger>] [-c cpu-list] [-H cpu-list]\\",
+		"	  [-P priority] [--dma-latency us] [--aa-only us] [-C [cgroup_name]] [-u|-k] [--warm-up s] [--deepest-idle-state n]",
 		"",
 		"	  -h/--help: print this menu",
 		"	  -a/--auto: set automatic trace mode, stopping the session if argument in us latency is hit",

@@ -495,11 +495,11 @@ static void timerlat_top_usage(char *usage)
 		"	  -s/--stack us: save the stack trace at the IRQ if a thread latency is higher than the argument in us",
 		"	  -c/--cpus cpus: run the tracer only on the given cpus",
 		"	  -H/--house-keeping cpus: run rtla control threads only on the given cpus",
-		"	  -C/--cgroup[=cgroup_name]: set cgroup, if no cgroup_name is passed, the rtla's cgroup will be inherited",
+		"	  -C/--cgroup [cgroup_name]: set cgroup, if no cgroup_name is passed, the rtla's cgroup will be inherited",
 		"	  -d/--duration time[s|m|h|d]: duration of the session",
 		"	  -D/--debug: print debug info",
 		"	     --dump-tasks: prints the task running on all CPUs if stop conditions are met (depends on !--no-aa)",
-		"	  -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 <command>: enable a trace event filter to the previous -e event",
 		"	     --trigger <command>: enable a trace event trigger to the previous -e event",

@@ -653,13 +653,7 @@ static struct common_params
 			break;
 		case 'C':
 			params->common.cgroup = 1;
-			if (!optarg) {
-				/* will inherit this cgroup */
-				params->common.cgroup_name = NULL;
-			} else if (*optarg == '=') {
-				/* skip the = */
-				params->common.cgroup_name = ++optarg;
-			}
+			params->common.cgroup_name = optarg;
 			break;
 		case 'D':
 			config_debug = 1;

@@ -722,14 +716,8 @@ static struct common_params
 			params->common.stop_total_us = get_llong_from_str(optarg);
 			break;
 		case 't':
-			if (optarg) {
-				if (optarg[0] == '=')
-					trace_output = &optarg[1];
-				else
-					trace_output = &optarg[0];
-			} else if (optind < argc && argv[optind][0] != '-')
-				trace_output = argv[optind];
-			else
+			trace_output = parse_optional_arg(argc, argv);
+			if (!trace_output)
 				trace_output = "timerlat_trace.txt";
 			break;
 		case 'u':

@@ -959,3 +959,29 @@ int auto_house_keeping(cpu_set_t *monitored_cpus)
 
 	return 1;
 }
+
+/**
+ * parse_optional_arg - Parse optional argument value
+ *
+ * Parse optional argument value, which can be in the form of:
+ * -sarg, -s/--long=arg, -s/--long arg
+ *
+ * Returns arg value if found, NULL otherwise.
+ */
+char *parse_optional_arg(int argc, char **argv)
+{
+	if (optarg) {
+		if (optarg[0] == '=') {
+			/* skip the = */
+			return &optarg[1];
+		} else {
+			return optarg;
+		}
+	/* parse argument of form -s [arg] and --long [arg]*/
+	} else if (optind < argc && argv[optind][0] != '-') {
+		/* consume optind */
+		return argv[optind++];
+	} else {
+		return NULL;
+	}
+}

@@ -24,6 +24,7 @@ long parse_seconds_duration(char *val);
 void get_duration(time_t start_time, char *output, int output_size);
 
 int parse_cpu_list(char *cpu_list, char **monitored_cpus);
+char *parse_optional_arg(int argc, char **argv);
 long long get_llong_from_str(char *start);
 
 static inline void