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>
diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
index c4622f1..613ed9a 100644
--- a/include/uapi/linux/perf_event.h
+++ b/include/uapi/linux/perf_event.h
@@ -802,6 +802,18 @@
*/
PERF_RECORD_ITRACE_START = 12,
+ /*
+ * Records the dropped/lost sample number.
+ *
+ * struct {
+ * struct perf_event_header header;
+ *
+ * u64 lost;
+ * struct sample_id sample_id;
+ * };
+ */
+ PERF_RECORD_LOST_SAMPLES = 13,
+
PERF_RECORD_MAX, /* non-ABI */
};