NAME

pmdapapi - papi performance metrics domain agent (PMDA)

SYNOPSIS

$PCP_PMDAS_DIR/pmdapapi [-d domain] [-l logfile]

DESCRIPTION

pmdapapi is a papi Performance Metrics Domain Agent (PMDA) which exposes hardware performance counters via the library Performance API (PAPI).

The metrics exported by the papi PMDA report values gathered from the hardware counters and metrics available, as reported by papi. Currently, only root users may access such metrics.

A brief description of the pmdapapi 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 papi.log is written in the current directory of pmcd(1) when pmdapapi 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.

Performance counters are activated automatically as they are fetched cyclically (such as via pmval(1) or pmlogger(1)). This automatic activation is temporary, and lasts only a number of seconds governed by the papi.control.auto_enable control value (default 120). In the case automatic activation is undesirable, one may disable it by setting the papi.control.auto_enable metric to 0.

Alternately, the pmstore(1) command can be used to permanently enable tracking particular metrics, or stop them on demand. Using the papi.control.enable and papi.control.disable metrics, one may set the metrics you wish to track using a space or comma separated list. Writing to the papi.control.reset metric disables all counters immediately. This may be useful if the system performance counters are needed for another profiling task.



# pmstore papi.control.enable "TOT_CYC TOT_INS"
papi.control.enable old value="" new value="TOT_CYC TOT_INS"
# pmval papi.system.TOT_CYC


            8.371E+04
# pmval papi.system.TOT_INS


            2.712E+04
# pmstore papi.control.disable "TOT_CYC,TOT_INS"
papi.control.disable old value="" new value="TOT_CYC,TOT_INS"

Fetching the papi.control.status metric provides an overview of all active counters.

By default, PAPI multiplexing, which allows support for collecting more metrics than supported by the hardware concurrently, is enabled. One may modify the papi.control.multiplex metric to disable multiplexing by setting it to 0.

Where possible, pmdapapi will expose available native perf and uncore events on the current hardware. It is not possible to count some native metrics and preset metrics concurrently.



# true -- automatically-enabled counters
# pmval -s3 papi.system.perf.BRANCH.LOADS
metric:    papi.system.perf.BRANCH.LOADS
host:      HOSTNAME
semantics: cumulative counter (converting to rate)
units:     count (converting to count / sec)
samples:   3
interval:  1.00 sec


            7530.    


            7539.    


            7543. 
# pmval -s3 papi.system.perf.BRANCH.MISSES
metric:    papi.system.perf.BRANCH.MISSES
host:      HOSTNAME
semantics: cumulative counter (converting to rate)
units:     count (converting to count / sec)
samples:   3
interval:  1.00 sec


             696.8   


             590.8   


             651.8
# true -- quick overview
# pminfo -f papi.control.status
papi.control.status


    value "Papi is running, has multiplexing enabled, perf.BRANCH.MISSES(114): 8960, perf.BRANCH.LOADS(110): 158400"
# true -- optional instant disable
# pmstore papi.control.disable "perf.BRANCH.LOADS,perf.BRANCH.MISSES"  
papi.control.disable old value="" new value="perf.BRANCH.LOADS,perf.BRANCH.MISSES"

INSTALLATION

If you want access to the names, help text and values for the papi performance metrics, do the following as root:



# cd $PCP_PMDAS_DIR/papi
# ./Install

If you want to undo the installation (and remove both PMDAs), do the following as root:



# cd $PCP_PMDAS_DIR/papi
# ./Remove

pmdapapi 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 pmdapapi
$PCP_PMDAS_DIR/papi/help: default help text file for the papi metrics
$PCP_PMDAS_DIR/papi/Install: installation script for the pmdapapi agent
$PCP_PMDAS_DIR/papi/Remove: undo installation script for the pmdapapi agent
$PCP_LOG_DIR/pmcd/sample.log: default log file for error messages and other information from pmdapapi

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).