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| author | Like Xu <like.xu@linux.intel.com> | 2019-10-27 18:52:39 +0800 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2019-11-15 11:44:07 +0100 |
| commit | 52ba4b0b99770e892f43da1238f437155acb8b58 (patch) | |
| tree | 18ee181729eb2cea9841a2bffb72d3da055ccabd | |
| parent | 3ca270fc9edb258d5bfa271bcf851614e9e6e7d4 (diff) | |
| download | powerpc-52ba4b0b99770e892f43da1238f437155acb8b58.tar.gz | |
perf/core: Provide a kernel-internal interface to pause perf_event
Exporting perf_event_pause() as an external accessor for kernel users (such
as KVM) who may do both disable perf_event and read count with just one
time to hold perf_event_ctx_lock. Also the value could be reset optionally.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Like Xu <like.xu@linux.intel.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
| -rw-r--r-- | include/linux/perf_event.h | 5 | ||||
| -rw-r--r-- | kernel/events/core.c | 18 |
2 files changed, 23 insertions, 0 deletions
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index d601df36e6710a..e9768bfc76f69e 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -1337,6 +1337,7 @@ extern void perf_event_disable_inatomic(struct perf_event *event); extern void perf_event_task_tick(void); extern int perf_event_account_interrupt(struct perf_event *event); extern int perf_event_period(struct perf_event *event, u64 value); +extern u64 perf_event_pause(struct perf_event *event, bool reset); #else /* !CONFIG_PERF_EVENTS: */ static inline void * perf_aux_output_begin(struct perf_output_handle *handle, @@ -1420,6 +1421,10 @@ static inline int perf_event_period(struct perf_event *event, u64 value) { return -EINVAL; } +static inline u64 perf_event_pause(struct perf_event *event, bool reset) +{ + return 0; +} #endif #if defined(CONFIG_PERF_EVENTS) && defined(CONFIG_CPU_SUP_INTEL) diff --git a/kernel/events/core.c b/kernel/events/core.c index e1b83d2731da01..fc9f5ebf484935 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -5029,6 +5029,24 @@ static void _perf_event_reset(struct perf_event *event) perf_event_update_userpage(event); } +/* Assume it's not an event with inherit set. */ +u64 perf_event_pause(struct perf_event *event, bool reset) +{ + struct perf_event_context *ctx; + u64 count; + + ctx = perf_event_ctx_lock(event); + WARN_ON_ONCE(event->attr.inherit); + _perf_event_disable(event); + count = local64_read(&event->count); + if (reset) + local64_set(&event->count, 0); + perf_event_ctx_unlock(event, ctx); + + return count; +} +EXPORT_SYMBOL_GPL(perf_event_pause); + /* * Holding the top-level event's child_mutex means that any * descendant process that has inherited this event will block |