KERNEL PMDAS(1)            General Commands Manual           KERNEL PMDAS(1)

NAME         top

       pmdaaix, pmdadarwin, pmdafreebsd, pmdalinux, pmdanetbsd, pmdasolaris,
       pmdawindows - operating  system  kernel  performance  metrics  domain

SYNOPSIS         top

       $PCP_PMDAS_DIR/aix/pmdaaix [-d domain] [-l logfile] [-U username]
       $PCP_PMDAS_DIR/darwin/pmdadarwin [-d domain] [-l logfile] [-U
       $PCP_PMDAS_DIR/freebsd/pmdafreebsd [-d domain] [-l logfile] [-U
       $PCP_PMDAS_DIR/linux/pmdalinux [-d domain] [-l logfile] [-U username]
       $PCP_PMDAS_DIR/netbsd/pmdanetbsd [-d domain] [-l logfile] [-U
       $PCP_PMDAS_DIR/solaris/pmdasolaris [-d domain] [-l logfile] [-U
       $PCP_PMDAS_DIR/windows/pmdawindows [-d domain] [-l logfile] [-U

DESCRIPTION         top

       Each supported platform has a kernel Performance Metrics Domain Agent
       (PMDA) which extracts performance metrics from the kernel of that
       platfrom.  A variety of platform-specific metrics are available, with
       an equally varied set of access mechanisms - typically this involves
       special system calls, or reading from files in kernel virtual
       filesystems such as the Linux sysfs and procfs filesystems.

       The platform kernel PMDA is one of the most critical components of
       the PCP installation, and must be as efficient and reliable as
       possible.  In all installations the default kernel PMDA will be
       installed as a shared library and thus executes directly within the
       pmcd(1) process.  This slightly reduces overheads associated with
       querying the metadata and values associated with these metrics (no
       message passing is required).

       Unlike many other PMDAs, the kernel PMDA exports a number of metric
       namespace subtrees, such as kernel, network, swap, mem, ipc, filesys,
       nfs, disk and hinv (hardware inventory).

       Despite usually running as shared libraries, most installations also
       include a stand-alone executable for the kernel PMDA.  This is to aid
       profiling and debugging activities, with dbpmda(1) for example.  In
       this case (but not for shared libraries), the following command line
       options are available:

       -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
            [platform].log is written in the current directory of pmcd(1)
            when pmda[platform] 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.

       -U   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

INSTALLATION         top

       Access to the names, help text and values for the kernel performance
       metrics is available by default - unlike most other agents, no action
       is required to enable them and they should not be removed.

FILES         top

                 default help text file for the the kernel metrics
                 default log file for error messages and other information
                 from the kernel PMDA.


       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).

SEE ALSO         top

       PCPIntro(1), dbpmda(1) pmcd(1), pcp.conf(5) and pcp.env(5).

COLOPHON         top

       This page is part of the PCP (Performance Co-Pilot) project.
       Information about the project can be found at ⟨⟩.
       If you have a bug report for this manual page, send it to  This page was obtained from the project's upstream
       Git repository ⟨⟩ on
       2017-09-15.  If you discover any rendering problems in this HTML ver‐
       sion 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 man‐
       ual page), send a mail to

Performance Co-Pilot                 PCP                     KERNEL PMDAS(1)