From ffbc7c027313f0c5572c1d94399445cf44036e12 Mon Sep 17 00:00:00 2001 From: Vince Weaver Date: Mon, 17 Oct 2016 10:50:40 -0400 Subject: [PATCH] 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 --- man2/perf_event_open.2 | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/man2/perf_event_open.2 b/man2/perf_event_open.2 index fa8b1bd37..59ad28959 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