linux-kernel - [patch] perf_event_open.2: PERF_RECORD_LOST

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Message-ID: <alpine.DEB.2.20.1610152201370.4137@macbook-air>
Date:   Sat, 15 Oct 2016 22:02:51 -0400 (EDT)
From:   Vince Weaver <vincent.weaver@...ne.edu>
To:     "Michael Kerrisk (man-pages)" <mtk.manpages@...il.com>
cc:     linux-man@...r.kernel.org, linux-kernel@...r.kernel.org,
        Kan Liang <kan.liang@...el.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Stephane Eranian <eranian@...il.com>
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 <vincent.weaver@...ne.edu>

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.
 .RE
+.TP
+.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.
+
+.in +4n
+.nf
+struct {
+    struct perf_event_header header;
+    u64 lost;
+    struct sample_id sample_id;
+};
+.fi
+.RS
+.TP
+.I lost
+the number of potentially lost samples.
+.RE
 .RE
 .SS Overflow handling
 Events can be set to notify when a threshold is crossed,