[PATCH] rt-tests: pi_stress: fix testing threads' smp affinity

[Jiafei Pan <Jiafei.Pan@nxp.com>]

This patch includes the following modification:
1. Make sure test threads and admin threads don't run on the same CPU
   Core if uniprocessor is not set or not on single Core platform to
   avoid starve admin threads.
2. Force to use SCHED_RR if more than one Groups running one a CPU
   Core to avoid test failure because threads in different Groups
   are using the same priority, SCHED_FIFO which is default policy
   and it maybe trigger deadlock of testing threads.

Signed-off-by: Jiafei Pan <Jiafei.Pan@nxp.com>
---
 src/pi_tests/pi_stress.c | 23 +++++++++++++++++++----
 1 file changed, 19 insertions(+), 4 deletions(-)

diff --git a/src/pi_tests/pi_stress.c b/src/pi_tests/pi_stress.c
index 49f89b7..8795908 100644
--- a/src/pi_tests/pi_stress.c
+++ b/src/pi_tests/pi_stress.c
@@ -237,6 +237,13 @@ int main(int argc, char **argv)
 	/* process command line arguments */
 	process_command_line(argc, argv);
 
+	if (ngroups > (num_processors - 1)) {
+		printf("Warning: One Core will used for administor thread, the other CPU Core will run test thread,\n");
+		printf("\t it will running more than one Group on one Core (groups > num_of_processors -1),\n");
+		printf("\t it will force to use SCHED_RR, or change groups number to be lower than %ld \n", num_processors);
+		policy = SCHED_RR;
+	}
+
 	/* set default sched attributes */
 	setup_sched_config(policy);
 
@@ -285,9 +292,17 @@ int main(int argc, char **argv)
 			break;
 	for (i = 0; i < ngroups; i++) {
 		groups[i].id = i;
-		groups[i].cpu = core++;
-		if (core >= num_processors)
-			core = 0;
+		if (num_processors == 1 || uniprocessor) {
+			groups[i].cpu = 0;
+		} else {
+			groups[i].cpu = core;
+			/* Find next non-admin Core */
+			do {
+				core++;
+				if (core >= num_processors)
+					core = 0;
+			} while (CPU_ISSET(core, &admin_cpu_mask));
+		}
 		if (create_group(&groups[i]) != SUCCESS)
 			return FAILURE;
 	}
@@ -1143,7 +1158,7 @@ int create_group(struct group_parameters *group)
 	CPU_ZERO(&mask);
 	CPU_SET(group->cpu, &mask);
 
-	pi_debug("group %d bound to cpu %ld\n", group->id, group->cpu);
+	printf("group %d bound to cpu %ld\n", group->id, group->cpu);
 
 	/* start the low priority thread */
 	pi_debug("creating low priority thread\n");
-- 
2.17.1