perf/x86/intel: Introduce PERF_RECORD_LOST_SAMPLES

After enlarging the PEBS interrupt threshold, there may be some mixed up
PEBS samples which are discarded by the kernel.

This patch makes the kernel emit a PERF_RECORD_LOST_SAMPLES record with
the number of possible discarded records when it is impossible to demux
the samples.

It makes sure the user is not left in the dark about such discards.

Signed-off-by: Kan Liang <kan.liang@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: acme@infradead.org
Cc: eranian@google.com
Link: http://lkml.kernel.org/r/1431285195-14269-8-git-send-email-kan.liang@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 5f192e1..a204d52 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -743,6 +743,9 @@ perf_event__output_id_sample(struct perf_event *event,
 			     struct perf_output_handle *handle,
 			     struct perf_sample_data *sample);
 
+extern void
+perf_log_lost_samples(struct perf_event *event, u64 lost);
+
 static inline bool is_sampling_event(struct perf_event *event)
 {
 	return event->attr.sample_period != 0;