LDP
/
man-pages
mirror of https://github.com/mkerrisk/man-pages
0
1
Fork 0
Code Releases Activity

perf_event_open.2: Improve sysfs files documentation 

This improves the documentation of the various
perf_event_open()-related sysfs files.

Signed-off-by: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
This commit is contained in:
Vince Weaver 2013-07-16 01:36:43 -04:00 committed by Michael Kerrisk
parent dbc01ecdff
commit e30dc77f5c
1 changed files with 39 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

48
man2/perf_event_open.2
View File

@ -1958,6 +1958,7 @@ The default value is
Maximum number of pages an unprivileged user can mlock (2) .
The default is 516 (kB).
.RE
Files in
.I /sys/bus/event_source/devices/
@ -1968,30 +1969,59 @@ Information on how to program these PMUs can be found under
.IR /sys/bus/event_source/devices/ .
Each subdirectory corresponds to a different PMU.
.TP
.I /sys/bus/event_source/devices/*/type
.IR /sys/bus/event_source/devices/*/type " (Since Linux 2.6.38)"
This contains an integer that can be used in the
.I type
field of perf_event_attr to indicate you wish to use this PMU.
.TP
.I /sys/bus/event_source/devices/*/rdpmc
[To be documented]
.IR /sys/bus/event_source/devices/*/rdpmc " (Since Linux 3.4)"
If this file is 1, then direct user-space access to the
performance counter registers is allowed via the rdpmc instruction.
This can be disabled by echoing 0 to the file.
.TP
.I /sys/bus/event_source/devices/*/format/
This sub-directory contains information on what bits in the
.IR /sys/bus/event_source/devices/*/format/ " (Since Linux 3.4)"
This sub-directory contains information on the architecture-specific
sub-fields available for programming the various
.I config
field of perf_event_attr correspond to.
fields in the perf_event_attr struct.
The content of each file is the name of the config field, followed
by a colon, followed by a series of integer bit ranges separated by
commas.
For example, the file
.I event
may contain the value
.I config1:1,6-10,44
which indicates that event is an attribute that occupies bits 1,6-10, and 44
of perf_event_attr::config1.
.TP
.I /sys/bus/event_source/devices/*/events/
.IR /sys/bus/event_source/devices/*/events/ " (Since Linux 3.4)"
This sub-directory contains files with pre-defined events.
The contents are strings describing the event settings
expressed in terms of the fields found in the
expressed in terms of the fields found in the previously mentioned
.I ./format/
directory.
These are not necessarily complete lists of all events supported by
a PMU, but usually a subset of events deemed useful or interesting.
The content of each file is a list of attribute names
separated by commas.
Each entry has an optional value (either hex or decimal).
If no value is specified than it is assumed to be a single-bit
field with a value of 1.
An example entry may look like this:
.I event=0x2,inv,ldlat=3
.TP
.I /sys/bus/event_source/devices/*/uevent
[To be documented]
This file is the standard kernel device interface
for injecting hotplug events.
.TP
.IR /sys/bus/event_source/devices/*/cpumask " (Since Linux 3.7)"
The cpumask file contains a comma-separated list of integers that
indicate a representative cpu number for each socket (package)
on the motherboard.
This is needed when setting up uncore or northbridge events, as
those PMUs present socket-wide events.
.RE
.SH RETURN VALUE
.BR perf_event_open ()