From: Vince Weaver <vincent.weaver@maine.edu>
To: "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com>
Cc: linux-man@vger.kernel.org, linux-kernel@vger.kernel.org,
Kan Liang <kan.liang@intel.com>,
Arnaldo Carvalho de Melo <acme@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>
Subject: [patch] perf_event_open.2: PERF_RECORD_MISC_PROC_MAP_PARSE_TIMEOUT
Date: Mon, 17 Oct 2016 10:50:40 -0400 (EDT) [thread overview]
Message-ID: <alpine.DEB.2.20.1610171048150.7683@macbook-air> (raw)
Linux 4.2 reserved a new bit from the misc field in the perf_event_open
mmap sample buffer:
PERF_RECORD_MISC_PROC_MAP_PARSE_TIMEOUT
Despite being reserved in the public include/uapi/linux/perf_event.h
header file, this bit is never set by the kernel, rather it is used
internally by the userspace "perf" utility to indicate that when
attempting to parse all of the /proc/xxx/maps files for the sample
it ended up taking too long so the scan was aborted.
Signed-off-by: Vince Weaver <vincent.weaver@maine.edu>
diff --git a/man2/perf_event_open.2 b/man2/perf_event_open.2
index fa8b1bd..59ad289 100644
--- a/man2/perf_event_open.2
+++ b/man2/perf_event_open.2
@@ -1822,6 +1822,14 @@ See also
.BR PERF_RECORD_MISC_EXT_RESERVED " (since Linux 2.6.35)"
.\" commit 1676b8a077c352085d52578fb4f29350b58b6e74
This indicates there is extended data available (currently not used).
+.TP
+.B PERF_RECORD_MISC_PROC_MAP_PARSE_TIMEOUT
+.\" commit 930e6fcd2bcce9bcd9d4aa7e755678d33f3fe6f4
+This bit is not set by the kernel.
+It is reserved for the userspace perf utility to indicate that
+.I /proc/xxx/maps
+parsing was taking too long and stopped and thus the mmap
+records may be truncated.
.RE
.TP
.I type
next reply other threads:[~2016-10-17 14:50 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-17 14:50 Vince Weaver [this message]
2016-10-18 6:14 ` Michael Kerrisk (man-pages)
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