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authorFrederic Weisbecker <fweisbec@gmail.com>2011-08-10 23:21:01 +0200
committerFrederic Weisbecker <fweisbec@gmail.com>2013-04-03 14:00:46 +0200
commit3ca277e41914ab344214ed50a41c14c48ae973f3 (patch)
treef8111dd8771c7be6d22e259f294b3117b6d1cb25 /kernel/time/Kconfig
parent3451d0243c3cdfd729b36f9684a14659d4895ca3 (diff)
downloadvexpress-lsk-3ca277e41914ab344214ed50a41c14c48ae973f3.tar.gz
nohz: Pack nohz Kconfig option in a menu of choices
Now the user has the choice between three implementations of the timer tick: * Static periodic tick * Idle dynticks * Full dynticks At least for now, these are mutually exclusive choices, so let's rely on the proper Kconfig feature to display these to the user. A new entry CONFIG_NO_HZ_IDLE is created and the old CONFIG_NO_HZ maps to it for config file backward compatibility. The old name was too general now that we have more granular dynticks implementations. While at it, add some explanation to help the user on his decision between the 3 entries. Reported-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Christoph Lameter <cl@linux.com> Cc: Geoff Levand <geoff@infradead.org> Cc: Gilad Ben Yossef <gilad@benyossef.com> Cc: Hakan Akkan <hakanakkan@gmail.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Kevin Hilman <khilman@linaro.org> Cc: Li Zhong <zhong@linux.vnet.ibm.com> Cc: Namhyung Kim <namhyung.kim@lge.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'kernel/time/Kconfig')
-rw-r--r--kernel/time/Kconfig28
1 files changed, 23 insertions, 5 deletions
diff --git a/kernel/time/Kconfig b/kernel/time/Kconfig
index c88fc43494c..27cc404ea18 100644
--- a/kernel/time/Kconfig
+++ b/kernel/time/Kconfig
@@ -75,17 +75,33 @@ config NO_HZ_COMMON
depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS
select TICK_ONESHOT
+# Kept around for compatibility, maps to NO_HZ_IDLE
config NO_HZ
- bool "Tickless System (Dynamic Ticks)"
+ bool
+
+choice
+ prompt "Timer tick handling"
+ default NO_HZ_IDLE if NO_HZ
+
+config PERIODIC_HZ
+ bool "Periodic timer ticks (constant rate, no dynticks)"
+ help
+ This option keeps the tick running periodically at a constant
+ rate, even when the CPU doesn't need it.
+
+config NO_HZ_IDLE
+ bool "Idle dynticks system (tickless idle)"
depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS
select NO_HZ_COMMON
help
- This option enables a tickless system: timer interrupts will
- only trigger on an as-needed basis both when the system is
- busy and when the system is idle.
+ This option enables a tickless idle system: timer interrupts
+ will only trigger on an as-needed basis when the system is idle.
+ This is usually interesting for energy saving.
+
+ Most of the time you want to say Y here.
config NO_HZ_EXTENDED
- bool "Full dynticks system"
+ bool "Full dynticks system (tickless single task)"
# NO_HZ_COMMON dependency
depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS
# RCU_USER_QS
@@ -112,6 +128,8 @@ config NO_HZ_EXTENDED
Say N.
+endchoice
+
config HIGH_RES_TIMERS
bool "High Resolution Timer Support"
depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS