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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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NAME | SYNOPSIS | DESCRIPTION | CONFIGURATION | INSTALLATION | EXAMPLES | FILES | PCP ENVIRONMENT | SEE ALSO | COLOPHON |
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PMDAPIPE(1) General Commands Manual PMDAPIPE(1)
pmdapipe - command output capture performance metrics domain
agent (PMDA)
$PCP_PMDAS_DIR/pipe/pmdapipe [-c configfile] [-d domain] [-l
logfile] [-m memory]
pmdapipe is a configurable command output monitoring Performance
Metrics Domain Agent (PMDA). It can be seen as analogous to a
restricted shell, where options can be passed to preset commands,
and each line of their output is converted into a performance
event. These events can be consumed by client tools like
pmval(1).
The pipe PMDA exports both event-style metrics reflecting
timestamped event records for text-oriented command output, as
well as the more orthodox sample-style metrics such as event
counts and throughput size values.
The PMDA is configured via a configfile which contains one line
for each process from which output can be captured, as described
in the ``CONFIGURATION'' section below.
A brief description of the pmdapipe command line options follows:
-c specifies an alternate configuration file for the PMDA. By
default, a file named $PCP_PMDAS_DIR/pipe/pipe.conf and any
files below the $PCP_SYSCONF_DIR/pipe.conf.d/ directory are
used.
-d It is absolutely crucial that the performance metrics domain
number specified here is unique and consistent. That is,
domain should be different for every PMDA on the one host,
and the same domain number should be used for the same PMDA
on all hosts.
-l Location of the log file. By default, a log file named
pipe.log is written in the current directory of pmcd(1) when
pmdapipe is started, i.e. $PCP_LOG_DIR/pmcd. If the log
file cannot be created or is not writable, output is written
to the standard error instead.
-m Limit the physical memory used by the PMDA to buffer event
records to maxsize bytes. As log events arrive at the PMDA,
they must be buffered until individual client tools request
the next batch since their previous batch of events. The
default maximum is 2 megabytes.
The set of allowed pipe commands is configured by simple text
file(s). The format is a single line for each command followed
by an optional access control section.
Blank lines and comments are permitted (even encouraged) in the
configuration file. A comment begins with a ``#'' character and
finishes at the end of the line.
Each command configuration line is of the form:
instance username command options
Where,
instance
is a string identifying the pipe command, also exported as
the metric instance identifier.
username
is the name of the user account under which the command
should run (e.g. "root")
command
is the path to the binary which will be run to generate
piped output
options
is an optional space-separated list of parameters to pass
to the command
This options list may contain numeric parameters
prefixed by the dollar-sign, and these will be
substituted with user-supplied values at the time
the command is run (similar to shell parameter
substitution).
Parameters are passed as a single space-separated or comma-
separated string to the pipe.firehose metric, using the
pmStore(3) interface. The pmval command provides store access
via its -x option. User-supplied parameters are restricted to
containing alphanumeric characters.
The access control section of the file must start with a line of
the form:
[access]
Leading and trailing whitespace may appear around and within the
brackets and the case of the access keyword is ignored. No other
text may appear on the line except a trailing comment.
Following this line, the remainder of the configuration file
should contain lines that allow or disallow use of commands from
particular users or groups.
User names and group names will be verified using the local
/etc/passwd and /etc/groups files (or an alternative directory
service), using the getpwent(3) and getgrent(3) routines.
Access for users or groups are allowed or disallowed by
specifying statements of the form:
allow user username : instance
disallow user username : instance
allow group groupname : instance
disallow group groupname : instance
The username and groupname names will be verified using the local
/etc/passwd and /etc/groups files (or an alternative directory
service), using the getpwent(3) and getgrent(3) routines.
The wildcard ``*'' can be used to refer to all instance names.
If you want access to the names, help text and values for the
pipe performance metrics, do the following as root:
# cd $PCP_PMDAS_DIR/pipe
# ./Install
This is an interactive installation process which prompts for
each log file path to be monitored (or command to be run), a
metric instance name to identify it, and whether access should be
restricted (refer to the -x option to pmval(1) for further
details).
If you want to undo the installation, do the following as root:
# cd $PCP_PMDAS_DIR/pipe
# ./Remove
pmdapipe is launched by pmcd and should never be executed
directly. The Install and Remove scripts notify pmcd when the
agent is installed or removed.
Following is a simple example of pmdapipe configuration and use
of the pipe metrics to run the btrace command, by user bob:
bob> cat $PCP_PMDAS_DIR/pipe/pipe.conf
# instance user command
rw_syscalls root perf script rw-by-file $1
bdev_trace root btrace -w $1 /dev/$2
[access]
allow user bob : *;
allow user jane : bdev_trace;
allow group perf : rw_syscalls;
bob> pmval -i bdev_trace -x '5 sda' pipe.firehose
8,2 5 1 0.000000000 25227 A WS 734332384 + 24 <- (253,2) 734330336
8,0 5 2 0.000000414 25227 A WS 735358432 + 24 <- (8,2) 734332384
8,0 5 3 0.000000756 25227 Q WS 735358432 + 24 [qemu-kvm]
[...5 seconds worth]
bob>
$PCP_PMCDCONF_PATH
command line options used to launch pmdapipe
$PCP_PMDAS_DIR/pipe/pipe.conf
default configuration file for the pipe metrics
$PCP_PMDAS_DIR/pipe/help
default help text file for the pipe metrics
$PCP_PMDAS_DIR/pipe/Install
installation script for the pmdapipe agent
$PCP_PMDAS_DIR/pipe/Remove
undo installation script for the pmdapipe agent
$PCP_LOG_DIR/pmcd/pipe.log
default log file for error messages and other information
from pmdapipe
$PCP_SYSCONF_DIR/pipe.conf.d
directory containing additional configuration files for
the pipe metrics
Environment variables with the prefix PCP_ are used to
parameterize the file and directory names used by PCP. On each
installation, the file /etc/pcp.conf contains the local values
for these variables. The $PCP_CONF variable may be used to
specify an alternative configuration file, as described in
pcp.conf(5).
PCPIntro(1), pmval(1), pmcd(1), getpwent(3), getgrent(3),
pmStore(3), pcp.conf(5) and pcp.env(5).
This page is part of the PCP (Performance Co-Pilot) project.
Information about the project can be found at
⟨http://www.pcp.io/⟩. If you have a bug report for this manual
page, send it to pcp@groups.io. This page was obtained from the
project's upstream Git repository
⟨https://github.com/performancecopilot/pcp.git⟩ on 2024-06-14.
(At that time, the date of the most recent commit that was found
in the repository was 2024-06-14.) If you discover any rendering
problems in this HTML version of the page, or you believe there
is a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
man-pages@man7.org
Performance Co-Pilot PCP PMDAPIPE(1)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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