__pmlocalpmda(3) — Linux manual page


PMLOCALPMDA(3)          Library Functions Manual          PMLOCALPMDA(3)

NAME         top

       __pmLocalPMDA - change the table of DSO PMDAs for
       PM_CONTEXT_LOCAL contexts

C SYNOPSIS         top

       #include "pmapi.h"
       #include "libpcp.h"

       int __pmLocalPMDA(int op, int domain, const char *name,
               const char *init);

       cc ... -lpcp

CAVEAT         top

       This documentation is intended for internal Performance Co-Pilot
       (PCP) developer use.

       These interfaces are not part of the PCP APIs that are guaranteed
       to remain fixed across releases, and they may not work, or may
       provide different semantics at some point in the future.

DESCRIPTION         top

       PCP contexts of type PM_CONTEXT_LOCAL are used by clients that
       wish to fetch metrics directly from one or more PMDAs on the
       local host without involving pmcd(1).  A PMDA that is to be used
       in this way must have been built as a Dynamic Shared Object

       Historically the table of PMDAs available for use with
       PM_CONTEXT_LOCAL was hardcoded to the following:

       * The PMDA (or PMDAs) that export the operating system
         performance data and data about process activity.
       * The mmv PMDA.
       * The sample PMDA provided $PCP_LITE_SAMPLE or $PMDA_LOCAL_SAMPLE
         is set in the environment - used mostly for QA and testing.

       The initial table of PMDAs available for use with
       PM_CONTEXT_LOCAL is now generated dynamically from all those
       PMDAs that have been installed as DSOs on the local host.  The
       one exception is the ``pmcd'' PMDA which only operates correctly
       in the address space of a running pmcd(1) process and so is not
       available to an application using a PM_CONTEXT_LOCAL context.

       __pmLocalPMDA provides a number of services to amend the table of
       PMDAs available for use with PM_CONTEXT_LOCAL.

       The op argument specifies the what should be done and takes one
       of the following values and actions:

       PM_LOCAL_ADD    Append an entry to the table for the PMDA with a
                       Performance Metrics Domain (PMD) of domain, the
                       path to the DSO PMDA is given by path and the
                       PMDA's initialization routine is init.

       PM_LOCAL_DEL    Removes all entries in the table where the domain
                       matches, or the path matches.  Setting the
                       arguments domain to -1 or path to NULL to force
                       matching on the other argument.  The init
                       argument is ignored.

       PM_LOCAL_CLEAR  Remove all entries from the table.  All the other
                       arguments are ignored in this case.

       The domain, name and init arguments have similar syntax and
       semantics to the associated fields in the pmcd(1) configuration
       file.  The one difference is the path argument which is used by
       __pmLocalPMDA to find a likely looking DSO by searching in this
       order: $PCP_PMDAS_DIR/path, path, $PCP_PMDAS_DIR/path.dso-suffix
       and finally path.dso-suffix (dso-suffix is the local platform
       specific default file name suffix for a DSO, e.g.  so for Linux,
       dylib for Mac OS X, dll for Windows, etc.).

RETURN VALUE         top

       In most cases, __pmLocalPMDA returns 0 to indicate success.  If
       op is invalid, then the return value is PM_ERR_CONV else if there
       is no matching table entry found for a PM_LOCAL_DEL operation,
       PM_ERR_INDOM is returned.

SEE ALSO         top

       pmcd(1), PMAPI(3), pmNewContext(3) and __pmSpecLocalPMDA(3).

COLOPHON         top

       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 2023-12-22.
       (At that time, the date of the most recent commit that was found
       in the repository was 2023-12-16.)  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

Performance Co-Pilot                                      PMLOCALPMDA(3)