From 3451d0243c3cdfd729b36f9684a14659d4895ca3 Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Wed, 10 Aug 2011 23:21:01 +0200 Subject: 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 Cc: Andrew Morton Cc: Chris Metcalf Cc: Christoph Lameter Cc: Geoff Levand Cc: Gilad Ben Yossef Cc: Hakan Akkan Cc: Ingo Molnar Cc: Kevin Hilman Cc: Li Zhong Cc: Namhyung Kim Cc: Paul E. McKenney Cc: Paul Gortmaker Cc: Peter Zijlstra Cc: Steven Rostedt Cc: Thomas Gleixner --- kernel/softirq.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel/softirq.c') diff --git a/kernel/softirq.c b/kernel/softirq.c index b4d252fd195b..de15813f2a66 100644 --- a/kernel/softirq.c +++ b/kernel/softirq.c @@ -348,7 +348,7 @@ void irq_exit(void) if (!in_interrupt() && local_softirq_pending()) invoke_softirq(); -#ifdef CONFIG_NO_HZ +#ifdef CONFIG_NO_HZ_COMMON /* Make sure that timer wheel updates are propagated */ if (idle_cpu(smp_processor_id()) && !in_interrupt() && !need_resched()) tick_nohz_irq_exit(); -- cgit v1.2.3 From 67826eae8c16dbf00c262be6ec15021bb42f69c4 Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Sat, 20 Apr 2013 17:43:13 +0200 Subject: nohz: Disable the tick when irq resume in full dynticks CPU Eventually try to disable tick on irq exit, now that the fundamental infrastructure is in place. Signed-off-by: Frederic Weisbecker Cc: Chris Metcalf Cc: Christoph Lameter Cc: Geoff Levand Cc: Gilad Ben Yossef Cc: Hakan Akkan Cc: Ingo Molnar Cc: Kevin Hilman Cc: Li Zhong Cc: Oleg Nesterov Cc: Paul E. McKenney Cc: Paul Gortmaker Cc: Peter Zijlstra Cc: Steven Rostedt Cc: Thomas Gleixner --- kernel/softirq.c | 19 ++++++++++++++----- 1 file changed, 14 insertions(+), 5 deletions(-) (limited to 'kernel/softirq.c') diff --git a/kernel/softirq.c b/kernel/softirq.c index de15813f2a66..8b1446d4a4db 100644 --- a/kernel/softirq.c +++ b/kernel/softirq.c @@ -337,6 +337,19 @@ static inline void invoke_softirq(void) } } +static inline void tick_irq_exit(void) +{ +#ifdef CONFIG_NO_HZ_COMMON + int cpu = smp_processor_id(); + + /* Make sure that timer wheel updates are propagated */ + if ((idle_cpu(cpu) && !need_resched()) || tick_nohz_full_cpu(cpu)) { + if (!in_interrupt()) + tick_nohz_irq_exit(); + } +#endif +} + /* * Exit an interrupt context. Process softirqs if needed and possible: */ @@ -348,11 +361,7 @@ void irq_exit(void) if (!in_interrupt() && local_softirq_pending()) invoke_softirq(); -#ifdef CONFIG_NO_HZ_COMMON - /* Make sure that timer wheel updates are propagated */ - if (idle_cpu(smp_processor_id()) && !in_interrupt() && !need_resched()) - tick_nohz_irq_exit(); -#endif + tick_irq_exit(); rcu_irq_exit(); sched_preempt_enable_no_resched(); } -- cgit v1.2.3