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NAME | C SYNOPSIS | DESCRIPTION | DIAGNOSTICS | SEE ALSO | COLOPHON |
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PMTRIMNAMESPACE(3) Library Functions Manual PMTRIMNAMESPACE(3)
pmTrimNameSpace - prune a performance metrics name space
#include <pcp/pmapi.h>
int pmTrimNameSpace(void);
cc ... -lpcp
In some (rare) cases it is helpful to prune the Performance
Metrics Name Space (PMNS) to match the available metrics.
The default PMNS that is accessible to a Performance Metrics
Application Programming Interface (PMAPI) client is provided by
the current PMAPI context:
• for a PMAPI context of type PM_CONTEXT_HOST the PMNS is
provided by pmcd(1) on the associated host and no pruning is
required
• for a PMAPI context of type PM_CONTEXT_ARCHIVE the PMNS is
stored within the associated Performance Co-Pilot (PCP)
archive and no pruning is required
• for a PMAPI context of type PM_CONTEXT_LOCAL at the first
PMAPI call requiring access to the PMNS it is loaded from the
default local location $PCP_VAR_DIR/pmns/root (or
$PMNS_DEFAULT) and no pruning is required.
If the default PMNS is in effect then calling pmTrimNameSpace is
a no-op and returns zero with no change to the PMNS.
PMAPI clients also have the option of over-riding the default
PMNS by loading a local PMNS from a file (see PMNS(5) for the
format) by calling pmLoadASCIINameSpace(3) or pmLoadNameSpace(3)
and this is when some PMNS pruning may be useful.
If a local PMNS is in effect when pmTrimNameSpace is called then
the first action is to restore the PMNS to the state as of the
completion of the last pmLoadASCIINameSpace(3) or
pmLoadNameSpace(3), so that the effects of consecutive calls to
pmTrimNameSpace are not additive.
The subsequent actions of pmTrimNameSpace depend on the type of
the current PMAPI context.
• For a context of type PM_CONTEXT_ARCHIVE the local PMNS is
trimmed to exclude metrics for which no description can be
found in the PCP archive. The PMNS is further trimmed to
remove empty subtrees that do not contain any performance
metric. Since PCP archives usually contain some subset of all
metrics named in a PMNS, pmTrimNameSpace effectively prunes
the application's PMNS to contain only the names of the
metrics in the archive.
• For a context of type PM_CONTEXT_HOST or PM_CONTEXT_LOCAL no
further action is required.
On success, pmTrimNameSpace returns zero.
PM_ERR_NOPMNS
there has been some earlier problem with establishing the
relevant PMNS
PM_ERR_NOCONTEXT
the current PMAPI context is invalid
pmlogger(1), PMAPI(3), pmLoadASCIINameSpace(3),
pmLoadNameSpace(3), pmNewContext(3) and PMNS(5).
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 [email protected]. This page was obtained from the
project's upstream Git repository
⟨https://github.com/performancecopilot/pcp.git⟩ on 2024-06-14.
(At that time, the date of the most recent commit that was found
in the repository was 2024-06-14.) 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
[email protected]
Performance Co-Pilot PCP PMTRIMNAMESPACE(3)
Pages that refer to this page: pmfetcharchive(3), pmgetpmnslocation(3), pmloadasciinamespace(3), pmloadnamespace(3)
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HTML rendering created 2024-06-26 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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