linux-kernel - [PATCH 2/3] sched/isolation: Enable CONFIG_CPU

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Message-Id: <1513260893-26616-3-git-send-email-frederic@kernel.org>
Date:   Thu, 14 Dec 2017 15:14:52 +0100
From:   Frederic Weisbecker <frederic@...nel.org>
To:     Ingo Molnar <mingo@...nel.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Chris Metcalf <cmetcalf@...lanox.com>,
        John Stultz <john.stultz@...aro.org>,
        Frederic Weisbecker <frederic@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Luiz Capitulino <lcapitulino@...hat.com>,
        Christoph Lameter <cl@...ux.com>,
        Wanpeng Li <kernellwp@...il.com>,
        Mike Galbraith <efault@....de>, Rik van Riel <riel@...hat.com>,
        kernel test robot <xiaolong.ye@...el.com>
Subject: [PATCH 2/3] sched/isolation: Enable CONFIG_CPU_ISOLATION=y by default

From: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>

The "isolcpus=" boot parameter support was always built-in before we
moved the related code under CONFIG_CPU_ISOLATION. Having it disabled by
default is very confusing for people accustomed to use this parameter.

So enable it by dafault to keep the previous behaviour but keep it
optable for those who want to tinify their kernels.

Signed-off-by: Frederic Weisbecker <frederic@...nel.org>
Cc: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Chris Metcalf <cmetcalf@...lanox.com>
Cc: Christoph Lameter <cl@...ux.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Luiz Capitulino <lcapitulino@...hat.com>
Cc: Mike Galbraith <efault@....de>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Rik van Riel <riel@...hat.com>
Cc: Wanpeng Li <kernellwp@...il.com>
Cc: Ingo Molnar <mingo@...nel.org>
Cc: John Stultz <john.stultz@...aro.org>
---
 init/Kconfig | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/init/Kconfig b/init/Kconfig
index 2934249..690a381 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -461,10 +461,14 @@ endmenu # "CPU/Task time and stats accounting"
 
 config CPU_ISOLATION
 	bool "CPU isolation"
+	default y
 	help
 	  Make sure that CPUs running critical tasks are not disturbed by
 	  any source of "noise" such as unbound workqueues, timers, kthreads...
-	  Unbound jobs get offloaded to housekeeping CPUs.
+	  Unbound jobs get offloaded to housekeeping CPUs. This is driven by
+	  the "isolcpus=" boot parameter.
+
+	  Say Y if unsure.
 
 source "kernel/rcu/Kconfig"
 
-- 
2.7.4