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Subject[patch] perf_event_open.2: PERF_RECORD_LOST_SAMPLES record type

Linux 4.2 added a new record type: PERF_RECORD_LOST_SAMPLES
It is generated when hardware samples (currently only Intel PEBS)
are lost.

Signed-off-by: Vince Weaver <>

diff --git a/man2/perf_event_open.2 b/man2/perf_event_open.2
index 9f33122..a47df2d 100644
--- a/man2/perf_event_open.2
+++ b/man2/perf_event_open.2
@@ -2551,6 +2551,25 @@ process ID of the thread starting an instruction trace.
.I tid
thread ID of the thread starting an instruction trace.
+.BR PERF_RECORD_LOST_SAMPLES " (since Linux 4.2)"
+\" f38b0dbb491a6987e198aa6b428db8692a6480f8
+When using hardware sampling (such as Intel PEBS) this record
+indicates some number of samples may have been lost.
+ +4n
+struct {
+ struct perf_event_header header;
+ u64 lost;
+ struct sample_id sample_id;
+.I lost
+the number of potentially lost samples.
.SS Overflow handling
Events can be set to notify when a threshold is crossed,
 \ /
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