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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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@ -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