linux-kernel - [tip:sched/core] housekeeping: Move it under its own config, independent from NO

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Date:   Tue, 24 Oct 2017 07:51:46 -0700
From:   tip-bot for Frederic Weisbecker <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     cl@...ux.com, riel@...hat.com, tglx@...utronix.de,
        torvalds@...ux-foundation.org, mingo@...nel.org,
        peterz@...radead.org, paulmck@...ux.vnet.ibm.com,
        lcapitulino@...hat.com, frederic@...nel.org,
        linux-kernel@...r.kernel.org, efault@....de, cmetcalf@...lanox.com,
        kernellwp@...il.com, hpa@...or.com
Subject: [tip:sched/core] housekeeping: Move it under its own config,
 independent from NO_HZ

Commit-ID:  59e334ed3d8cbf7d1f0180690f072d0043fb9e24
Gitweb:     https://git.kernel.org/tip/59e334ed3d8cbf7d1f0180690f072d0043fb9e24
Author:     Frederic Weisbecker <frederic@...nel.org>
AuthorDate: Tue, 24 Oct 2017 15:06:56 +0200
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Tue, 24 Oct 2017 15:20:15 +0200

housekeeping: Move it under its own config, independent from NO_HZ

Split housekeeping config from CONFIG_NO_HZ_FULL. This way we finally
separate the isolation code from nohz.

Although a dependency to CONFIG_NO_HZ_FULL remains for now until the
housekeeping code doesn't deal anymore with nohz internals directly.

Signed-off-by: Frederic Weisbecker <frederic@...nel.org>
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: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Rik van Riel <riel@...hat.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Wanpeng Li <kernellwp@...il.com>
Link: http://lkml.kernel.org/r/1508850421-10058-8-git-send-email-frederic@kernel.org
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 include/linux/housekeeping.h | 6 +++---
 init/Kconfig                 | 8 ++++++++
 kernel/Makefile              | 2 +-
 3 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/include/linux/housekeeping.h b/include/linux/housekeeping.h
index 320cc2b..dcbec47 100644
--- a/include/linux/housekeeping.h
+++ b/include/linux/housekeeping.h
@@ -5,7 +5,7 @@
 #include <linux/init.h>
 #include <linux/tick.h>
 
-#ifdef CONFIG_NO_HZ_FULL
+#ifdef CONFIG_CPU_ISOLATION
 DECLARE_STATIC_KEY_FALSE(housekeeping_overriden);
 extern int housekeeping_any_cpu(void);
 extern const struct cpumask *housekeeping_cpumask(void);
@@ -27,11 +27,11 @@ static inline const struct cpumask *housekeeping_cpumask(void)
 
 static inline void housekeeping_affine(struct task_struct *t) { }
 static inline void housekeeping_init(void) { }
-#endif /* CONFIG_NO_HZ_FULL */
+#endif /* CONFIG_CPU_ISOLATION */
 
 static inline bool housekeeping_cpu(int cpu)
 {
-#ifdef CONFIG_NO_HZ_FULL
+#ifdef CONFIG_CPU_ISOLATION
 	if (static_branch_unlikely(&housekeeping_overriden))
 		return housekeeping_test_cpu(cpu);
 #endif
diff --git a/init/Kconfig b/init/Kconfig
index 78cb246..6f52e6f 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -472,6 +472,14 @@ config TASK_IO_ACCOUNTING
 
 endmenu # "CPU/Task time and stats accounting"
 
+config CPU_ISOLATION
+	bool "CPU isolation"
+	depends on NO_HZ_FULL
+	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.
+
 source "kernel/rcu/Kconfig"
 
 config BUILD_BIN2C
diff --git a/kernel/Makefile b/kernel/Makefile
index c63f893..5b01feb 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -109,7 +109,7 @@ obj-$(CONFIG_CRASH_DUMP) += crash_dump.o
 obj-$(CONFIG_JUMP_LABEL) += jump_label.o
 obj-$(CONFIG_CONTEXT_TRACKING) += context_tracking.o
 obj-$(CONFIG_TORTURE_TEST) += torture.o
-obj-$(CONFIG_NO_HZ_FULL) += housekeeping.o
+obj-$(CONFIG_CPU_ISOLATION) += housekeeping.o
 
 obj-$(CONFIG_HAS_IOMEM) += memremap.o