diff --git a/lib/event/scheduler_dynamic.c b/lib/event/scheduler_dynamic.c
index ffc9dc963..d9fa634de 100644
--- a/lib/event/scheduler_dynamic.c
+++ b/lib/event/scheduler_dynamic.c
@@ -161,6 +161,11 @@ balance(struct spdk_scheduler_core_info *cores_info, int cores_count,
 					target_lcore = g_next_lcore;
 					g_next_lcore = spdk_env_get_next_core(g_next_lcore);
 
+					/* Do not use main core if it is too busy for new thread */
+					if (target_lcore == g_main_lcore && thread_busy > main_core_idle) {
+						continue;
+					}
+
 					if (spdk_cpuset_get_cpu(cpumask, target_lcore)) {
 						lw_thread->new_lcore = target_lcore;
 
diff --git a/test/unit/lib/event/reactor.c/reactor_ut.c b/test/unit/lib/event/reactor.c/reactor_ut.c
index c1b5c4e8f..56941b331 100644
--- a/test/unit/lib/event/reactor.c/reactor_ut.c
+++ b/test/unit/lib/event/reactor.c/reactor_ut.c
@@ -560,6 +560,9 @@ test_scheduler(void)
 		spdk_poller_unregister(&busy);
 	}
 
+	reactor->busy_tsc = 0;
+	reactor->idle_tsc = UINT32_MAX;
+
 	/* Run scheduler again, this time all threads are busy */
 	_reactors_scheduler_gather_metrics(NULL, NULL);