linux-kernel - [patch 2/4] isolation: set HK_FLAG_SCHED on nohz

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Message-ID: <20200401121342.930480720@redhat.com>
Date:   Wed, 01 Apr 2020 09:10:20 -0300
From:   Marcelo Tosatti <mtosatti@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     Frederic Weisbecker <fweisbec@...il.com>,
        Chris Friesen <chris.friesen@...driver.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Jim Somerville <Jim.Somerville@...driver.com>,
        Christoph Lameter <cl@...ux.com>,
        Frederic Weisbecker <frederic@...nel.org>,
        Marcelo Tosatti <mtosatti@...hat.com>
Subject: [patch 2/4] isolation: set HK_FLAG_SCHED on nohz_full CPUs

Avoid idle load balancing on nohz_full CPUs.

This avoids assigning tasks to such CPUs, when they enter idle.

Suggested-by: Frederic Weisbecker <frederic@...nel.org>
Signed-off-by: Marcelo Tosatti <mtosatti@...hat.com>

Index: linux-2.6/kernel/sched/isolation.c
===================================================================
--- linux-2.6.orig/kernel/sched/isolation.c
+++ linux-2.6/kernel/sched/isolation.c
@@ -140,7 +140,8 @@ static int __init housekeeping_nohz_full
 {
 	unsigned int flags;
 
-	flags = HK_FLAG_TICK | HK_FLAG_WQ | HK_FLAG_TIMER | HK_FLAG_RCU | HK_FLAG_MISC;
+	flags = HK_FLAG_TICK | HK_FLAG_WQ | HK_FLAG_TIMER | HK_FLAG_RCU |
+		HK_FLAG_MISC | HK_FLAG_SCHED;
 
 	return housekeeping_setup(str, flags);
 }