nohz: New APIs to re-evaluate the tick on full dynticks CPUs

Provide two new helpers in order to notify the full dynticks CPUs about
some internal system changes against which they may reconsider the state
of their tick. Some practical examples include: posix cpu timers, perf tick
and sched clock tick.

For now the notifying handler, implemented through IPIs, is a stub
that will be implemented when we get the tick stop/restart infrastructure
in.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
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: Oleg Nesterov <oleg@redhat.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>

1 files changed, 4 insertions, 0 deletions

diff --git a/include/linux/tick.h b/include/linux/tick.h
index b4e3b0c9639e..c2dcfb18f65b 100644
--- a/include/linux/tick.h
+++ b/include/linux/tick.h
@@ -159,8 +159,12 @@ static inline u64 get_cpu_iowait_time_us(int cpu, u64 *unused) { return -1; }
 
 #ifdef CONFIG_NO_HZ_FULL
 extern int tick_nohz_full_cpu(int cpu);
+extern void tick_nohz_full_kick(void);
+extern void tick_nohz_full_kick_all(void);
 #else
 static inline int tick_nohz_full_cpu(int cpu) { return 0; }
+static inline void tick_nohz_full_kick(void) { }
+static inline void tick_nohz_full_kick_all(void) { }
 #endif