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authorFrederic Weisbecker <fweisbec@gmail.com>2011-08-10 23:21:01 +0200
committerFrederic Weisbecker <fweisbec@gmail.com>2013-04-03 13:56:03 +0200
commit3451d0243c3cdfd729b36f9684a14659d4895ca3 (patch)
tree5307f4492708ae089dd0a6d81b54f9e606707ca8 /kernel/time
parentab71d36ddb9e60d4ddb28a187718815d38c3c666 (diff)
downloadvexpress-lsk-3451d0243c3cdfd729b36f9684a14659d4895ca3.tar.gz
nohz: Rename CONFIG_NO_HZ to CONFIG_NO_HZ_COMMON
We are planning to convert the dynticks Kconfig options layout into a choice menu. The user must be able to easily pick any of the following implementations: constant periodic tick, idle dynticks, full dynticks. As this implies a mutual exclusion, the two dynticks implementions need to converge on the selection of a common Kconfig option in order to ease the sharing of a common infrastructure. It would thus seem pretty natural to reuse CONFIG_NO_HZ to that end. It already implements all the idle dynticks code and the full dynticks depends on all that code for now. So ideally the choice menu would propose CONFIG_NO_HZ_IDLE and CONFIG_NO_HZ_EXTENDED then both would select CONFIG_NO_HZ. On the other hand we want to stay backward compatible: if CONFIG_NO_HZ is set in an older config file, we want to enable CONFIG_NO_HZ_IDLE by default. But we can't afford both at the same time or we run into a circular dependency: 1) CONFIG_NO_HZ_IDLE and CONFIG_NO_HZ_EXTENDED both select CONFIG_NO_HZ 2) If CONFIG_NO_HZ is set, we default to CONFIG_NO_HZ_IDLE We might be able to support that from Kconfig/Kbuild but it may not be wise to introduce such a confusing behaviour. So to solve this, create a new CONFIG_NO_HZ_COMMON option which gathers the common code between idle and full dynticks (that common code for now is simply the idle dynticks code) and select it from their referring Kconfig. Then we'll later create CONFIG_NO_HZ_IDLE and map CONFIG_NO_HZ to it for backward compatibility. 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')
-rw-r--r--kernel/time/Kconfig13
-rw-r--r--kernel/time/tick-sched.c12
2 files changed, 15 insertions, 10 deletions
diff --git a/kernel/time/Kconfig b/kernel/time/Kconfig
index 726c33e00da..c88fc43494c 100644
--- a/kernel/time/Kconfig
+++ b/kernel/time/Kconfig
@@ -64,16 +64,21 @@ config GENERIC_CMOS_UPDATE
if GENERIC_CLOCKEVENTS
menu "Timers subsystem"
-# Core internal switch. Selected by NO_HZ / HIGH_RES_TIMERS. This is
+# Core internal switch. Selected by NO_HZ_COMMON / HIGH_RES_TIMERS. This is
# only related to the tick functionality. Oneshot clockevent devices
# are supported independ of this.
config TICK_ONESHOT
bool
+config NO_HZ_COMMON
+ bool
+ depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS
+ select TICK_ONESHOT
+
config NO_HZ
bool "Tickless System (Dynamic Ticks)"
depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS
- select TICK_ONESHOT
+ 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
@@ -81,14 +86,14 @@ config NO_HZ
config NO_HZ_EXTENDED
bool "Full dynticks system"
- # NO_HZ dependency
+ # NO_HZ_COMMON dependency
depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS
# RCU_USER_QS
depends on HAVE_CONTEXT_TRACKING && SMP
# RCU_NOCB_CPU dependency
depends on TREE_RCU || TREE_PREEMPT_RCU
depends on VIRT_CPU_ACCOUNTING_GEN
- select NO_HZ
+ select NO_HZ_COMMON
select RCU_USER_QS
select RCU_NOCB_CPU
select CONTEXT_TRACKING_FORCE
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 57bb3fe5aaa..ccfc2086cd4 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -104,7 +104,7 @@ static void tick_sched_do_timer(ktime_t now)
{
int cpu = smp_processor_id();
-#ifdef CONFIG_NO_HZ
+#ifdef CONFIG_NO_HZ_COMMON
/*
* Check if the do_timer duty was dropped. We don't care about
* concurrency: This happens only when the cpu in charge went
@@ -124,7 +124,7 @@ static void tick_sched_do_timer(ktime_t now)
static void tick_sched_handle(struct tick_sched *ts, struct pt_regs *regs)
{
-#ifdef CONFIG_NO_HZ
+#ifdef CONFIG_NO_HZ_COMMON
/*
* When we are idle and the tick is stopped, we have to touch
* the watchdog as we might not schedule for a really long
@@ -235,7 +235,7 @@ core_initcall(init_tick_nohz_extended);
/*
* NOHZ - aka dynamic tick functionality
*/
-#ifdef CONFIG_NO_HZ
+#ifdef CONFIG_NO_HZ_COMMON
/*
* NO HZ enabled ?
*/
@@ -907,7 +907,7 @@ static inline void tick_check_nohz(int cpu)
static inline void tick_nohz_switch_to_nohz(void) { }
static inline void tick_check_nohz(int cpu) { }
-#endif /* NO_HZ */
+#endif /* CONFIG_NO_HZ_COMMON */
/*
* Called from irq_enter to notify about the possible interruption of idle()
@@ -992,14 +992,14 @@ void tick_setup_sched_timer(void)
now = ktime_get();
}
-#ifdef CONFIG_NO_HZ
+#ifdef CONFIG_NO_HZ_COMMON
if (tick_nohz_enabled)
ts->nohz_mode = NOHZ_MODE_HIGHRES;
#endif
}
#endif /* HIGH_RES_TIMERS */
-#if defined CONFIG_NO_HZ || defined CONFIG_HIGH_RES_TIMERS
+#if defined CONFIG_NO_HZ_COMMON || defined CONFIG_HIGH_RES_TIMERS
void tick_cancel_sched_timer(int cpu)
{
struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);