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authorFrederic Weisbecker <fweisbec@gmail.com>2013-04-20 15:27:08 +0200
committerFrederic Weisbecker <fweisbec@gmail.com>2013-04-22 20:16:04 +0200
commitff442c51f6543378cf23107c75b7949dc64a9119 (patch)
tree7c3cf3031f0bb0b8f0c9e8a170d17922b3bd1926
parentce831b38ca4920739a7a5b0c73b921da41f03718 (diff)
downloadlinaro-lsk-ff442c51f6543378cf23107c75b7949dc64a9119.tar.gz
nohz: Re-evaluate the tick from the scheduler IPI
The scheduler IPI is used by the scheduler to kick full dynticks CPUs asynchronously when more than one task are running or when a new timer list timer is enqueued. This way the destination CPU can decide to restart the tick to handle this new situation. Now let's call that kick in the scheduler IPI. (Reusing the scheduler IPI rather than implementing a new IPI was suggested by Peter Zijlstra a while ago) 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>
-rw-r--r--include/linux/tick.h2
-rw-r--r--kernel/sched/core.c4
-rw-r--r--kernel/time/tick-sched.c2
3 files changed, 6 insertions, 2 deletions
diff --git a/include/linux/tick.h b/include/linux/tick.h
index d290168335b..e31e67623ea 100644
--- a/include/linux/tick.h
+++ b/include/linux/tick.h
@@ -160,11 +160,13 @@ static inline u64 get_cpu_iowait_time_us(int cpu, u64 *unused) { return -1; }
#ifdef CONFIG_NO_HZ_FULL
extern void tick_nohz_init(void);
extern int tick_nohz_full_cpu(int cpu);
+extern void tick_nohz_full_check(void);
extern void tick_nohz_full_kick(void);
extern void tick_nohz_full_kick_all(void);
#else
static inline void tick_nohz_init(void) { }
static inline int tick_nohz_full_cpu(int cpu) { return 0; }
+static inline void tick_nohz_full_check(void) { }
static inline void tick_nohz_full_kick(void) { }
static inline void tick_nohz_full_kick_all(void) { }
#endif
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 69f71335984..9ad35005f1c 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1398,7 +1398,8 @@ static void sched_ttwu_pending(void)
void scheduler_ipi(void)
{
- if (llist_empty(&this_rq()->wake_list) && !got_nohz_idle_kick())
+ if (llist_empty(&this_rq()->wake_list) && !got_nohz_idle_kick()
+ && !tick_nohz_full_cpu(smp_processor_id()))
return;
/*
@@ -1415,6 +1416,7 @@ void scheduler_ipi(void)
* somewhat pessimize the simple resched case.
*/
irq_enter();
+ tick_nohz_full_check();
sched_ttwu_pending();
/*
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 884a9f302a0..4d74a68b2c3 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -151,7 +151,7 @@ bool have_nohz_full_mask;
* Re-evaluate the need for the tick on the current CPU
* and restart it if necessary.
*/
-static void tick_nohz_full_check(void)
+void tick_nohz_full_check(void)
{
/*
* STUB for now, will be filled with the full tick stop/restart