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NAME | C SYNOPSIS | DESCRIPTION | CAVEAT | DIAGNOSTICS | SEE ALSO | COLOPHON |
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PMDACHILDREN(3) Library Functions Manual PMDACHILDREN(3)
pmdaChildren - translate a PMID to a set of dynamic performance
metric names
#include <pcp/pmapi.h>
#include <pcp/pmda.h>
int pmdaChildren(char *name, int traverse, char ***offspring,
int **status, pmdaExt *pmda);
cc ... -lpcp_pmda -lpcp
As part of the Performance Metrics Domain Agent (PMDA) API (see
PMDA(3)), pmdaChildren is the generic callback for returning dy‐
namic metric names (and their status) that are descendants of
name.
Because implementing dynamic performance metrics requires specific
PMDA support, and the facility is an optional component of a PMDA
(most PMDAs do not support dynamic performance metrics), pmdaChil‐
dren is a skeleton implementation that returns PM_ERR_NAME.
A PMDA that supports dynamic performance metrics will provide a
private callback that replaces pmdaChildren (by assignment to ver‐
sion.four.children of the pmdaInterface structure) and takes the
initial metric name and returns names via offspring[] and the leaf
or non-leaf status of each via status[].
If traverse is 0, then the behaviour is akin to pmGetChildren(3)
and offspring[] contains the relative name component for the imme‐
diate descendants of name.
If traverse is 1, then the behaviour is akin to pmTraversePMNS(3)
and offspring[] contains the absolute names of all dynamic metrics
that are decedents of name.
The resulting list of pointers offspring and the string values
(the names) that the pointers reference will have been allocated
by pmdaChildren with a single call to malloc(3), and the caller of
pmdaChildren will call free(offspring) to release the space when
it is no longer required. The same holds true for the status ar‐
ray, namely the caller of pmdaChildren will call free(status) to
release the space when it is no longer required.
The PMDA must be using PMDA_INTERFACE_4 or later, as specified in
the call to pmdaDSO(3) or pmdaDaemon(3).
pmdaChildren returns PM_ERR_NAME if the name is not recognized or
cannot be translated, otherwise the number of descendent metric
names found.
PMAPI(3), PMDA(3), pmdaDaemon(3), pmdaDSO(3), pmdaMain(3),
pmGetChildren(3) and pmTraversePMNS(3).
This page is part of the PCP (Performance Co-Pilot) project. In‐
formation 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
2025-08-11. (At that time, the date of the most recent commit
that was found in the repository was 2025-08-11.) 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 man-pages@man7.org
Performance Co-Pilot PCP PMDACHILDREN(3)
Pages that refer to this page: pmdamain(3)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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