pmdadso(3) — Linux manual page


PMDADSO(3)              Library Functions Manual              PMDADSO(3)

NAME         top

       pmdaDSO - initialize the PMDA to run as a DSO

C SYNOPSIS         top

       #include <pcp/pmapi.h>
       #include <pcp/pmda.h>

       int pmdaDSO(pmdaInterface *dispatch, int interface, char *name,
               char *helptext);

       cc ... -lpcp_pmda -lpcp

DESCRIPTION         top

       pmdaDSO initializes the pmdaInterface structure to use the
       interface extensions, assuming the PMDA(3) is to be run as a DSO.
       The pmdaInterface structure is initialized with:

       name   The name of the agent.

              The default path to the help text (see pmdaText(3)).  If
              no help text is installed, or you are not using
              pmdaText(3), then this should be set to NULL, otherwise
              helptext will be copied, so the storage associated with
              helptext may be released after the call to pmdaDSO.

       The callbacks are initialized to pmdaProfile(3), pmdaFetch(3),
       pmdaDesc(3), pmdaText(3), pmdaInstance(3) and pmdaStore(3).

       The interface structure also contains the domain of the PMDA(3),
       which is defined in the pmcd(1) configuration file. The domain is
       used to initialize the metric and instance descriptors (see

CAVEAT         top

       The PMDA must be using PMDA_INTERFACE_2 or later.

       Once pmdaDSO has been called, it is expected that the
       pmdaInterface structure pointed to by dispatch will remain
       accessible to the routines in libpcp_pmda (not reclaimed off the
       stack, not freed or oherwise released, etc.).  If the caller
       needs to move or relocate the pmdaInterface structure for any
       reason, then after the move pmdaInterfaceMoved(3) must be called
       to resestablish the internal integrity of the pmdaInterface
       structure at the new location before any other routine in
       libpcp_pmda is called.

DIAGNOSTICS         top

       Incompatible version of pmcd detected
              When pmcd(1) creates the pmdaInterface structure, the
              dispatch.comm.version field is set to the highest protocol
              that pmcd(1) understands.  This message indicates that the
              pmcd(1) process does not understand the protocol used by

       Unable to allocate memory for pmdaExt structure
              In addition, dispatch->status is set to a value less than

SEE ALSO         top

       pmcd(1), PMAPI(3), PMDA(3), pmdaDaemon(3), pmdaInit(3),
       pmdaInterfaceMoved(3) and pmdaText(3).

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 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               PCP                        PMDADSO(3)

Pages that refer to this page: pmda(3)pmdaattribute(3)pmdachildren(3)pmdadaemon(3)pmdadesc(3)pmdafetch(3)pmdagetoptions(3)pmdahelp(3)pmdainit(3)pmdainstance(3)pmdainterfacemoved(3)pmdalabel(3)pmdaname(3)pmdaopenlog(3)pmdapmid(3)pmdaprofile(3)pmdastore(3)pmdatext(3)