Commit-ID: 460775df4680b4593d8449bc171008578625a850
Gitweb: http://git.kernel.org/tip/460775df4680b4593d8449bc171008578625a850
Author: Frederic Weisbecker <fweisbec@xxxxxxxxx>
AuthorDate: Wed, 24 Jul 2013 23:52:27 +0200
Committer: Frederic Weisbecker <fweisbec@xxxxxxxxx>
CommitDate: Wed, 14 Aug 2013 17:14:57 +0200
nohz: Optimize full dynticks state checks with static keys
These APIs are frequenctly accessed and priority is given
to optimize the full dynticks off-case in order to let
distros enable this feature without suffering from
significant performance regressions.
Let's inline these APIs and optimize them with static keys.
Signed-off-by: Frederic Weisbecker <fweisbec@xxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Li Zhong <zhong@xxxxxxxxxxxxxxxxxx>
Cc: Mike Galbraith <efault@xxxxxx>
Cc: Kevin Hilman <khilman@xxxxxxxxxx>
---
include/linux/tick.h | 25 +++++++++++++++++++++++--
kernel/time/tick-sched.c | 14 ++------------
2 files changed, 25 insertions(+), 14 deletions(-)
diff --git a/include/linux/tick.h b/include/linux/tick.h
index 9180f4b..c60b079 100644
--- a/include/linux/tick.h
+++ b/include/linux/tick.h
@@ -10,6 +10,8 @@
#include <linux/irqflags.h>
#include <linux/percpu.h>
#include <linux/hrtimer.h>
+#include <linux/context_tracking_state.h>
+#include <linux/cpumask.h>
#ifdef CONFIG_GENERIC_CLOCKEVENTS
@@ -158,15 +160,34 @@ static inline u64 get_cpu_iowait_time_us(int cpu, u64 *unused) { return -1; }
# endif /* !CONFIG_NO_HZ_COMMON */
#ifdef CONFIG_NO_HZ_FULL
+extern bool tick_nohz_full_running;
+extern cpumask_var_t tick_nohz_full_mask;
+
+static inline bool tick_nohz_full_enabled(void)
+{
+ if (!static_key_false(&context_tracking_enabled))
+ return false;
+
+ return tick_nohz_full_running;
+}
+
+static inline bool tick_nohz_full_cpu(int cpu)
+{
+ if (!tick_nohz_full_enabled())
+ return false;
+
+ return cpumask_test_cpu(cpu, tick_nohz_full_mask);
+}
+
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);
extern void tick_nohz_task_switch(struct task_struct *tsk);
#else
static inline void tick_nohz_init(void) { }
-static inline int tick_nohz_full_cpu(int cpu) { return 0; }
+static inline bool tick_nohz_full_enabled(void) { return false; }
+static inline bool tick_nohz_full_cpu(int cpu) { return false; }
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) { }
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index b28dee4..0b78873 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -149,7 +149,7 @@ static void tick_sched_handle(struct tick_sched *ts, struct pt_regs *regs)
}
#ifdef CONFIG_NO_HZ_FULL
-static cpumask_var_t tick_nohz_full_mask;
+cpumask_var_t tick_nohz_full_mask;
bool tick_nohz_full_running;
static bool can_stop_full_tick(void)
@@ -270,14 +270,6 @@ out:
local_irq_restore(flags);
}
-int tick_nohz_full_cpu(int cpu)
-{
- if (!tick_nohz_full_running)
- return 0;
-
- return cpumask_test_cpu(cpu, tick_nohz_full_mask);
-}
-
/* Parse the boot-time nohz CPU list from the kernel parameters. */
static int __init tick_nohz_full_setup(char *str)
{
@@ -359,8 +351,6 @@ void __init tick_nohz_init(void)
cpulist_scnprintf(nohz_full_buf, sizeof(nohz_full_buf), tick_nohz_full_mask);
pr_info("NO_HZ: Full dynticks CPUs: %s.\n", nohz_full_buf);
}
-#else
-#define tick_nohz_full_running (0)
#endif
/*
@@ -738,7 +728,7 @@ static bool can_stop_idle_tick(int cpu, struct tick_sched *ts)
return false;
}
- if (tick_nohz_full_running) {
+ if (tick_nohz_full_enabled()) {
/*
* Keep the tick alive to guarantee timekeeping progression
* if there are full dynticks CPUs around
--
To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
|