NAME

pmdatrace - application-level transaction performance metrics domain agent

SYNOPSIS

$PCP_PMDAS_DIR/trace/pmdatrace [-d domain] [-l logfile] [-A access] [-I port] [-M username] [-N buckets] [-T period] [-U units]

DESCRIPTION

pmdatrace is a Performance Metrics Domain Agent (PMDA) which exports transaction performance metrics from application processes which use the pcp_trace library described in pmdatrace(3).

A brief description of the pmdatrace command line options follows:

-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 trace.log is written in the current directory of pmcd(1) when pmdatrace 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.
-A: Host-based access control for pmdatrace. access must be either an allow or deny specification, using either allow:hostspec:maxconns or disallow:hostspec, where `allow' and `disallow' are keywords, `hostspec' is a host specification conforming to the format used by both pmcd(1) and pmlogger(1), and `maxconns' is the maximum number of connections allowed from a given `hostspec'. Using a maximum connections of zero specifies an unlimited number of connections for the accompanying `hostspec'.
-I: Communicate with pcp_trace clients via the given Internet port. This can alternatively be specified by setting $PCP_TRACE_PORT in the environment to some valid port number (use of the -I option overrides this). The default port number is 4323.
-T: period defines the aggregation period used to compute the recent averages and extrema. Specified as a time interval using the syntax described in PCPIntro(1) for the common -t PCP argument, e.g. 30 seconds or 1 min. The default is 60 seconds.
-M: User account under which to run the agent. The default is the unprivileged "pcp" account in current versions of PCP, but in older versions the superuser account ("root") was used by default.
-N: Internally, the aggregation period is divided into bucket divisions, and the rolling average is recomputed every period/bucket seconds. For example, the defaults correspond to -T 60 and -N 12, which means the average is recomputed every five seconds for a period covering the prior 60 seconds.
-U: This option allows the dimension and scale associated with the observation value metric to be configured. units is a comma-separated string of six integer values, which are the space dimension, time dimension, count dimension, space scale, time scale, and count scale, respectively. The default dimension and scale is ``none'', which is equivalent to presenting ``0,0,0,0,0,0'' as the argument to -U. The units associated with a metric are most easily viewed using the -d (metric description) option to pminfo(1). The Install script described below steps through this option quite explicitly, so it is recommended that the Install script be used for building up the units specification.

Essentially, the exported metrics provide statistics on the time for completion of each transaction, and an average count of transactions completed and watch points passed over a given time period.

INSTALLATION

In order for a host to export the names, help text and values for the Trace performance metrics, do the following as root:



# cd $PCP_PMDAS_DIR/trace
# ./Install

If you want to undo the installation, do the following as root:



# cd $PCP_PMDAS_DIR/trace
# ./Remove

pmdatrace 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.

FILES

$PCP_PMCDCONF_PATH: command line options used to launch pmdatrace
$PCP_PMDAS_DIR/trace/help: default help text file for the trace metrics
$PCP_DEMOS_DIR/trace/*: example programs which use the pcp_trace library
$PCP_PMDAS_DIR/trace/Install: installation script for the pmdatrace agent
$PCP_PMDAS_DIR/trace/Remove: undo installation script for pmdatrace
$PCP_LOG_DIR/pmcd/trace.log: default log file for error messages and other information from pmdatrace

PCP ENVIRONMENT

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).