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perf_event_open.2: Document PERF_RECORD_MISC_PROC_MAP_PARSE_TIMEOUT 

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 user-space
"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>
This commit is contained in:
Vince Weaver 2016-10-17 10:50:40 -04:00 committed by Michael Kerrisk
parent 2046b8ac01
commit ffbc7c0273
1 changed files with 8 additions and 0 deletions
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man2/perf_event_open.2
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@ -1822,6 +1822,14 @@ See also
.BR PERF_RECORD_MISC_EXT_RESERVED " (since Linux 2.6.35)" .BR PERF_RECORD_MISC_EXT_RESERVED " (since Linux 2.6.35)"
.\" commit 1676b8a077c352085d52578fb4f29350b58b6e74 .\" commit 1676b8a077c352085d52578fb4f29350b58b6e74
This indicates there is extended data available (currently not used). 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 .RE
.TP .TP
.I type .I type