Re: [patch] perf_event_open.2: PERF_RECORD_MISC_PROC_MAP_PARSE_TIMEOUT
From: Michael Kerrisk (man-pages)
Date: Tue Oct 18 2016 - 02:15:37 EST
On 10/17/2016 04:50 PM, Vince Weaver wrote:
> Linux 4.2 reserved a new bit from the misc field in the perf_event_open
> mmap sample buffer:
> 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@xxxxxxxxx>
> 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).
> +.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.
> .I type
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/