pmdaproc - Online in the Cloud

PROGRAM:

NAME

pmdaproc - process performance metrics domain agent (PMDA)

SYNOPSIS

$PCP_PMDAS_DIR/proc/pmdaproc [-AL] [-d domain] [-l logfile] [-r cgroup] [-U username]

DESCRIPTION

pmdaproc is a Performance Metrics Domain Agent (PMDA) which extracts performance metrics
describing the state of the individual processes running on a Linux system.

The proc PMDA exports metrics that measure the memory, processor and other resource use of
each process, as well as summary information collated across all of the running processes.
The PMDA uses credentials passed from the PMAPI(3) monitoring tool identifying the user
requesting the information, to ensure that only values the user is allowed to access are
returned by the PMDA. This involves the PMDA temporarily changing its effective user and
group identifiers for the duration of requests for instances and values. In other words,
system calls to extract information are performed as the user originating the request and
not as a privileged user. The mechanisms available for transfer of user credentials are
described further in the PCPIntro(1) page.

A brief description of the pmdaproc command line options follows:

-A Disables use of the credentials provided by PMAPI client tools, and simply runs
everything under the "root" account.

-L Changes the per-process instance domain used by most procproc metrics to include
threads as well.

-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 proc.log is written in the
current directory of pmcd(1) when pmdaproc 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.

-r Restrict the set of processes exported in the per-process instance domain to only
those processes that are contained by the specified cgroup resource container. This
option provides an optional finer granularity to the monitoring, and can also be used
to reduce the resources consumed by pmdaproc during requests for instances and
values.

-U User account under which to run the agent. The default is the privileged "root"
account, with seteuid (2) and setegid (2) switching for accessing most information.

HOTPROC OVERVIEW

The pmdaproc Performance Metrics Domain Agent (PMDA) includes an additional set of per-
process metrics with an instance domain of processes restricted to an "interesting" or
"hot" set. Unlike the stock metrics exported by the proc PMDA, which have an instance
domain equal to the current processes, hot metrics have an instance domain which is a
subset of this. This hotproc instance domain is determined by a configurable predicate
evaluated over some refresh interval.

As well as the equivalent per-process proc metrics, hotproc provides a cpuburn metric
which specifies the CPU utilization of the process over the refresh interval, total
metrics which indicate how much of the available CPU time the "interesting" processes
account for, predicate metrics which show the values of the reserved variables (see below)
that are being used in the hotproc predicate, and control metrics for controlling the
agent.

HOTPROC CONFIGURATION

The configuration file consists of one predicate used to determine if a process should be
in the interesting set or not.

An example configuration file may be found at $PCP_PMDAS_DIR/proc/samplehotproc.conf

This file with any modifications can be copied to $PCP_PMDAS_DIR/proc/hotproc.conf in
order to configure the hot metrics. The pmstore(1) and pmStore(3) interfaces can be used
as well (described below).

The predicate is described using the language specified below. The symbols are based on
those used by the C(1) and awk(1) languages.

Boolean Connectives
&& (and), || (or), ! (not), () (precedence overriding)

Number comparators
< , <= , > , >= , == , !=

String comparators
== , !=

String/Pattern comparators
~ (string matches pattern) , !~ (string does not match pattern)

Reserved variables
uid (user id; type integer) uname (user name; type string), gid (group id; type
integer) gname (group name; type string), fname (process file name; type string),
psargs (process file name with args; type string), cpuburn (cpu utilization; type
float), iodemand (I/O demand - Kbytes read/written per second; type float),
ctxswitch (number of context switches per second; type float), syscalls (number of
system calls per second; type float), virtualsize (virtual size in Kbytes; type
float), residentsize (resident size in Kbytes; type float), iowait (blocked and raw
io wait in secs/sec; type float), schedwait (time waiting in run queue in secs/sec;
type float).

Literal values
1234 (positive integer), 0.35 (positive float), "foobar" (string; delimited by "),
/[fF](o)+bar/ (pattern; delimited by /), true (boolean), false (boolean)

Comments
#this is a comment (from # to the end of the line).

Examples
cpuburn > 0.2 # cpu utilization of more than 20%
cpuburn > 0.2 && uname == "root"
cpuburn > 0.2 && (uname == "root" || uname == "hot")
psargs ~ /pmda/ && cpuburn > 0.4

The hotproc.predicate metrics may be used to see what the values of the reserved variables
are that were used by the predicate at the last refresh. They do not cover the reserved
variables which are already exported elsewhere. A hotproc.predicate metric may not have a
value if it is not referenced in the configuration predicate.

DYNAMIC CONFIGURATION

The hot metrics can also be configured at runtime through the pmstore(1) interface (and,
implicitly, the pmStore(3) API)

Examples
pmstore hotproc.control.config 'fname == "mingetty"'
pmstore hotproc.control.config 'uid == 0'

To force the config file to be reloaded:
pmstore hotproc.control.reload_config "1"

INSTALLATION

The proc PMDA is installed and available by default. If you want to undo the
installation, do the following as root:

# cd $PCP_PMDAS_DIR/proc
# ./Remove

If you want to establish access to the names, help text and values for the proc
performance metrics once more, after removal, do the following as root:

# cd $PCP_PMDAS_DIR/proc
# ./Install

pmdaproc is launched by pmcd(1) and should never be executed directly. The Install and
Remove scripts notify pmcd(1) when the agent is installed or removed.

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