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| author | Peter Zijlstra <peterz@infradead.org> | 2010-02-24 17:35:13 +0100 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2010-02-24 17:35:13 +0100 |
| commit | 2e5f15f4c51efd5fdb1ea97380c38d3f8c32d3e9 (patch) | |
| tree | a16390eb35fbbe648b84899bbc35ff1f1dc51467 /include | |
| parent | 8452259b8aefef73981b2ffbc23d5245d19bd140 (diff) | |
| download | lwn-2e5f15f4c51efd5fdb1ea97380c38d3f8c32d3e9.tar.gz lwn-2e5f15f4c51efd5fdb1ea97380c38d3f8c32d3e9.zip | |
perf_events: defer poll() wakeups to softirq
Use timer softirq for wakeups on preempt_rt
Normally pending work is work that cannot be done from NMI context, such
as wakeups and disabling the counter. The pending work is a single
linked list using atomic ops so that it functions from NMI context.
Normally this is called from IRQ context through use of an self-IPI
(x86) or upon enabling hard interrupts (powerpc). Architectures that do
not implement perf_event_set_pending() nor call
perf_event_do_pending() upon leaving NMI context will get a polling
fallback from the timer softirq.
However, in -rt we cannot do the wakeup from IRQ context because its a
wait_queue wakup, which can be O(n), so defer all wakeups to the softirq
fallback by creating a second pending list that's only processed from
there.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/perf_event.h | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index a177698d95e2..f57b3abc5e0e 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -645,6 +645,9 @@ struct perf_event { int pending_kill; int pending_disable; struct perf_pending_entry pending; +#ifdef CONFIG_PREEMPT_RT + struct perf_pending_entry pending_softirq; +#endif atomic_t event_limit; @@ -753,6 +756,7 @@ extern void perf_event_exit_task(struct task_struct *child); extern void perf_event_free_task(struct task_struct *task); extern void set_perf_event_pending(void); extern void perf_event_do_pending(void); +extern void perf_event_do_pending_softirq(void); extern void perf_event_print_debug(void); extern void __perf_disable(void); extern bool __perf_enable(void); @@ -883,6 +887,7 @@ static inline int perf_event_init_task(struct task_struct *child) { return 0; } static inline void perf_event_exit_task(struct task_struct *child) { } static inline void perf_event_free_task(struct task_struct *task) { } static inline void perf_event_do_pending(void) { } +static inline void perf_event_do_pending_softirq(void) { } static inline void perf_event_print_debug(void) { } static inline void perf_disable(void) { } static inline void perf_enable(void) { } |