Subject: sched: Limit the number of task migrations per batch
From: Thomas Gleixner <tglx@linutronix.de>
Date: Mon, 06 Jun 2011 12:12:51 +0200
Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patches-4.19.25-rt16.tar.xz

Put an upper limit on the number of tasks which are migrated per batch
to avoid large latencies.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 kernel/sched/core.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -44,7 +44,11 @@ const_debug unsigned int sysctl_sched_fe
  * Number of tasks to iterate in a single balance run.
  * Limited because this is done with IRQs disabled.
  */
+#ifdef CONFIG_PREEMPT_RT_FULL
+const_debug unsigned int sysctl_sched_nr_migrate = 8;
+#else
 const_debug unsigned int sysctl_sched_nr_migrate = 32;
+#endif
 
 /*
  * period over which we measure -rt task CPU usage in us.
