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From: Thomas Gleixner <tglx@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@kernel.org>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Subject: [patch 1/5] sched: Limit the number of task migrations per batch on RT
Date: Tue, 28 Sep 2021 14:24:25 +0200 (CEST)	[thread overview]
Message-ID: <20210928122411.425097596@linutronix.de> (raw)
In-Reply-To: 20210928122339.502270600@linutronix.de

Batched task migrations are a source for large latencies as they keep the
scheduler from running while processing the migrations.

Limit the batch size to 8 instead of 32 when running on a RT enabled
kernel.

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
@@ -74,7 +74,11 @@ 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
+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.


  reply	other threads:[~2021-09-28 12:24 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-28 12:24 [patch 0/5] sched: Miscellaneous RT related tweaks Thomas Gleixner
2021-09-28 12:24 ` Thomas Gleixner [this message]
2021-10-01 15:05   ` [tip: sched/core] sched: Limit the number of task migrations per batch on RT tip-bot2 for Thomas Gleixner
2021-10-05 14:11   ` tip-bot2 for Thomas Gleixner
2021-09-28 12:24 ` [patch 2/5] sched: Disable TTWU_QUEUE " Thomas Gleixner
2021-10-01 15:05   ` [tip: sched/core] " tip-bot2 for Thomas Gleixner
2021-10-05 14:11   ` tip-bot2 for Thomas Gleixner
2021-09-28 12:24 ` [patch 3/5] sched: Move kprobes cleanup out of finish_task_switch() Thomas Gleixner
2021-10-01 15:05   ` [tip: sched/core] " tip-bot2 for Thomas Gleixner
2021-10-05 14:11   ` tip-bot2 for Thomas Gleixner
2021-09-28 12:24 ` [patch 4/5] sched: Delay task stack freeing on RT Thomas Gleixner
2021-09-29 11:54   ` Peter Zijlstra
2021-10-01 16:12     ` Andy Lutomirski
2021-10-01 17:24       ` Thomas Gleixner
2021-10-01 18:48         ` Andy Lutomirski
2021-10-01 19:02           ` Andy Lutomirski
2021-10-01 20:54             ` Thomas Gleixner
2021-09-28 12:24 ` [patch 5/5] sched: Move mmdrop to RCU " Thomas Gleixner
2021-09-29 12:02   ` Peter Zijlstra
2021-09-29 13:05     ` Thomas Gleixner
2021-10-01 15:05   ` [tip: sched/core] " tip-bot2 for Thomas Gleixner
2021-10-05 14:11   ` tip-bot2 for Thomas Gleixner

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