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perf/core: Provide a kernel-internal interface to recalibrate event period

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Currently, perf_event_period() is used by user tools via ioctl. Based on
naming convention, exporting perf_event_period() for kernel users (such
as KVM) who may recalibrate the event period for their assigned counter
according to their requirements.

The perf_event_period() is an external accessor, just like the
perf_event_{en,dis}able() and should thus use perf_event_ctx_lock().

Suggested-by: Kan Liang <kan.liang@linux.intel.com>
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>
This commit is contained in:
Like Xu
2019-10-27 18:52:38 +08:00
committed by Paolo Bonzini
parent 02d496cfb8
commit 3ca270fc9e
2 changed files with 26 additions and 7 deletions
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5
include/linux/perf_event.h
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@@ -1336,6 +1336,7 @@ extern void perf_event_disable_local(struct perf_event *event);
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);
#else /* !CONFIG_PERF_EVENTS: */
static inline void *
perf_aux_output_begin(struct perf_output_handle *handle,
@@ -1415,6 +1416,10 @@ static inline void perf_event_disable(struct perf_event *event) { }
static inline int __perf_event_disable(void *info) { return -1; }
static inline void perf_event_task_tick(void) { }
static inline int perf_event_release_kernel(struct perf_event *event) { return 0; }
static inline int perf_event_period(struct perf_event *event, u64 value)
{
return -EINVAL;
}
#endif
#if defined(CONFIG_PERF_EVENTS) && defined(CONFIG_CPU_SUP_INTEL)