[PATCH v3 0/2] rt-tests: cyclictest: Add option to specify main pid affinity

@@ -836,6 +836,8 @@ static void display_help(int error)
 	       "	 --laptop	   Save battery when running cyclictest\n"
 	       "			   This will give you poorer realtime results\n"
 	       "			   but will not drain your battery so quickly\n"
+	       "         --mainaffinity=[CPUSET]  Run the main thread on CPU #N. This only affects\n"
+	       "                           the main thread and not the measurement threads\n"
 	       "-m       --mlockall        lock current and future memory allocations\n"
 	       "-M       --refresh_on_max  delay updating the screen until a new max\n"
 	       "			   latency is hit. Useful for low bandwidth.\n"

@@ -891,6 +893,7 @@ static int quiet;
 static int interval = DEFAULT_INTERVAL;
 static int distance = -1;
 static struct bitmask *affinity_mask = NULL;
+static struct bitmask *main_affinity_mask = NULL;
 static int smp = 0;
 static int setaffinity = AFFINITY_UNSPECIFIED;
 

@@ -944,7 +947,7 @@ enum option_values {
 	OPT_AFFINITY=1, OPT_BREAKTRACE, OPT_CLOCK,
 	OPT_DISTANCE, OPT_DURATION, OPT_LATENCY,
 	OPT_FIFO, OPT_HISTOGRAM, OPT_HISTOFALL, OPT_HISTFILE,
-	OPT_INTERVAL, OPT_LOOPS, OPT_MLOCKALL, OPT_REFRESH,
+	OPT_INTERVAL, OPT_LOOPS, OPT_MAINAFFINITY, OPT_MLOCKALL, OPT_REFRESH,
 	OPT_NANOSLEEP, OPT_NSECS, OPT_OSCOPE, OPT_PRIORITY,
 	OPT_QUIET, OPT_PRIOSPREAD, OPT_RELATIVE, OPT_RESOLUTION,
 	OPT_SYSTEM, OPT_SMP, OPT_THREADS, OPT_TRIGGER,

@@ -981,6 +984,7 @@ static void process_options(int argc, char *argv[], int max_cpus)
 			{"interval",         required_argument, NULL, OPT_INTERVAL },
 			{"laptop",	     no_argument,	NULL, OPT_LAPTOP },
 			{"loops",            required_argument, NULL, OPT_LOOPS },
+			{"mainaffinity",     required_argument, NULL, OPT_MAINAFFINITY},
 			{"mlockall",         no_argument,       NULL, OPT_MLOCKALL },
 			{"refresh_on_max",   no_argument,       NULL, OPT_REFRESH },
 			{"nsecs",            no_argument,       NULL, OPT_NSECS },

@@ -1083,6 +1087,16 @@ static void process_options(int argc, char *argv[], int max_cpus)
 		case 'l':
 		case OPT_LOOPS:
 			max_cycles = atoi(optarg); break;
+		case OPT_MAINAFFINITY:
+			if (optarg) {
+				parse_cpumask(optarg, max_cpus, &main_affinity_mask);
+			} else if (optind < argc &&
+			           (atoi(argv[optind]) ||
+			            argv[optind][0] == '0' ||
+			            argv[optind][0] == '!')) {
+				parse_cpumask(argv[optind], max_cpus, &main_affinity_mask);
+			}
+			break;
 		case 'm':
 		case OPT_MLOCKALL:
 			lockall = 1; break;

@@ -1790,7 +1804,9 @@ int main(int argc, char **argv)
 	}
 
 	/* Restrict the main pid to the affinity specified by the user */
-	if (affinity_mask != NULL) {
+	if (main_affinity_mask != NULL) {
+		try_numa_sched_setaffinity(getpid(), main_affinity_mask);
+	} else if (affinity_mask != NULL) {
 		try_numa_sched_setaffinity(getpid(), affinity_mask);
 		if (verbose)
 			printf("Using %u cpus.\n",

@@ -1791,13 +1791,7 @@ int main(int argc, char **argv)
 
 	/* Restrict the main pid to the affinity specified by the user */
 	if (affinity_mask != NULL) {
-		int res;
-
-		errno = 0;
-		res = numa_sched_setaffinity(getpid(), affinity_mask);
-		if (res != 0)
-			warn("Couldn't setaffinity in main thread: %s\n", strerror(errno));
-
+		try_numa_sched_setaffinity(getpid(), affinity_mask);
 		if (verbose)
 			printf("Using %u cpus.\n",
 				numa_bitmask_weight(affinity_mask));

@@ -18,4 +18,6 @@ int cpu_for_thread_ua(int thread_num, int max_cpus);
 
 int parse_cpumask(char *str, int max_cpus, struct bitmask **cpumask);
 
+void try_numa_sched_setaffinity(__pid_t pid, struct bitmask *cpumask);
+
 #endif

@@ -138,3 +138,14 @@ int parse_cpumask(char *str, int max_cpus, struct bitmask **cpumask)
 
 	return 0;
 }
+
+void try_numa_sched_setaffinity(pid_t pid, struct bitmask *cpumask)
+{
+	int res;
+
+	errno = 0;
+	res = numa_sched_setaffinity(pid, cpumask);
+	if (res != 0)
+		warn("Couldn't setaffinity for thread %d: %s\n", pid,
+		     strerror(errno));
+}