[PATCH 2/7] nohz: Introduce adaptive nohz config

[Frederic Weisbecker]

Prepare a config option for the full adaptive nohz feature.
This way we can start to put the related code under appropriate
ifdefs.

Signed-off-by: Frederic Weisbecker <fweisbec@xxxxxxxxx>
Cc: Alessio Igor Bogani <abogani@xxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Avi Kivity <avi@xxxxxxxxxx>
Cc: Chris Metcalf <cmetcalf@xxxxxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Cc: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx>
Cc: Geoff Levand <geoff@xxxxxxxxxxxxx>
Cc: Gilad Ben Yossef <gilad@xxxxxxxxxxxxx>
Cc: Hakan Akkan <hakanakkan@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Kevin Hilman <khilman@xxxxxx>
Cc: Max Krasnyansky <maxk@xxxxxxxxxxxx>
Cc: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Stephen Hemminger <shemminger@xxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Sven-Thorsten Dietrich <thebigcorporation@xxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
---
 arch/Kconfig        |    8 ++++++++
 kernel/time/Kconfig |    7 +++++++
 2 files changed, 15 insertions(+), 0 deletions(-)

diff --git a/arch/Kconfig b/arch/Kconfig
index 8c3d957..a71c698 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -251,6 +251,14 @@ config HAVE_CMPXCHG_DOUBLE
 config ARCH_WANT_OLD_COMPAT_IPC
 	bool
 
+config HAVE_NO_HZ_FULL
+        bool
+	help
+	 An arch should select this symbols if it provides
+	 the kernel entry/exit hooks necessary to implement
+	 full tickless support. This includes syscall entry/exit,
+	 exceptions entry/exit and do_notify_resume() hooks.
+
 config HAVE_ARCH_SECCOMP_FILTER
 	bool
 	help
diff --git a/kernel/time/Kconfig b/kernel/time/Kconfig
index 0883fa1..5ac4b74 100644
--- a/kernel/time/Kconfig
+++ b/kernel/time/Kconfig
@@ -65,6 +65,13 @@ config NO_HZ
 	  This option enables a tickless idle system: timer interrupts will
 	  only trigger on an as-needed basis when the system is idle.
 
+config NO_HZ_FULL
+        bool "Full tickless system (Dynamic Ticks)"
+	depends on NO_HZ && HAVE_NO_HZ_FULL
+	help
+	  This option enables a full adaptive tickless system: timer
+	  interrupts will globally only trigger on an as-needed basis.
+
 config HIGH_RES_TIMERS
 	bool "High Resolution Timer Support"
 	depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS
-- 
1.7.5.4

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