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NAME | INTRODUCTION | GENERAL ERRORS | CLIENT-PMCD ERRORS | CLIENT-ARCHIVE ERRORS | TIME CONTROL ERRORS | NAMESPACE ERRORS | PMCD-PMDA ERRORS | PCP ENVIRONMENT | SEE ALSO | COLOPHON |
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PCPINTRO(3) Library Functions Manual PCPINTRO(3)
PCPIntro - introduction to the Performance Co-Pilot (PCP)
libraries
Performance Co-Pilot (PCP) is a toolkit designed for monitoring
and managing system-level performance.
The PCP libraries support the APIs required to create new
performance monitoring tools and new agents (or PMDAs) to export
performance data. The libpcp library is used in both cases. The
libpcp_pmda library is used only for PMDAs.
Individual library routines are documented in their own manual
page entries.
Most routines return an integer value; greater than equal to zero
for success and less than zero for an error. The error codes
have symbolic names defined in <pcp/pmapi.h>. Other negative
values are used to encode errors that can be mapped to the
traditional errno values defined in <errno.h>, with the value
negated. To translate all PCP error codes into useful messages
use either pmerr(1) or pmErrStr(3); the latter may also be used
to decode the -errno cases.
These common errors may occur in various PCP interactions.
PM_ERR_TIMEOUT
Timeout waiting for a response from PMCD
Many interactions between PCP applications involve
synchronous message passing, and these are subject to timeout
constraints. These errors are most frequently encountered
when using network connections with slow data rates or long
latencies.
For client-pmcd timeouts, refer to PCPIntro(1) for
environment variables that may be used to modify the timeout
thresholds. For pmcd-PMDA timeouts refer to the -t and -q
options of pmcd(1) and the PCP metric pmcd.control.timeout
that can be dynamically changed with pmstore(1).
PM_ERR_APPVERSION
Metric not supported by this version of monitored application
Some performance metrics are unavailable from specific
versions of the associated PMDA, or may be unavailable
because the underlying instrumentation has changed or is not
installed or is not enabled. This error is used in results
from pmFetch(3) to indicate these situations.
PM_ERR_IPC
IPC protocol failure
Generic protocol failure on a pipe or socket connecting two
PCP applications, e.g. client-pmcd, or client-pmtime, or
PMDA-pmcd or pmlc-pmlogger.
PM_ERR_TEXT
One-line or help text is not available
Set by a PMDA, and passed back to a PCP client, to indicate
that the PMDA is unable to supply the requested metric or
instance domain help text.
PM_ERR_VALUE
Missing metric value(s)
This error is used for a number of conditions in which the
value of a performance metric is inappropriate for the
context in which it is being used, e.g.
(a) Bad value for the metric pmcd.timezone when trying to set
the timezone via pmNewContextZone(3) for a remote or
archive context.
(b) Attempting to interpolate values for a metric with non-
numeric data type from a set of PCP archives.
(c) A bad result data structure passed to pmStore(3).
PM_ERR_NAME
Unknown metric name
Just what the message says.
PM_ERR_PMID
Unknown or illegal metric identifier
Just what the message says.
PM_ERR_INDOM
Unknown or illegal instance domain identifier
A request nominates an instance domain that is unknown or
PM_INDOM_NULL. May occur as a consequence of the instance
domain identifier passed by a PCP client to pmGetInDom(3),
pmLookupInDom(3), pmNameInDom(3), pmGetInDomArchive(3),
pmLookupInDomArchive(3), pmNameInDomArchive(3) or a request
passed from pmcd(1) to a PMDA.
PM_ERR_EOF
IPC channel closed
End of file on a pipe or socket connecting two PCP
applications, e.g. client-pmcd, or client-pmtime or
PMDA-pmcd.
PM_ERR_NOCONTEXT
Attempt to use an illegal context
Typically caused by a PCP client that tries to make calls
before calling pmNewContext(3) or after calling
pmDestroyContext(3).
PM_ERR_PERMISSION
No permission to perform requested operation
PCP-specific access controls apply to pmcd(1) and
pmlogger(1). Platform-specific permission errors are
returned as -EPERM.
PM_ERR_CONV
Impossible value or scale conversion
Some value conversion requests are illegal, e.g. bad debug
flag symbolic name for -D/--debug option, or asking
pmExtractValue(3) to translate non-numeric data types to
numbers and vice versa.
PM_ERR_TRUNC
Truncation in value conversion
Some conversion requests to pmExtractValue(3) cannot be
performed based on the metric types and values involved, in
this case conversion would result in loss of precision.
PM_ERR_SIGN
Negative value in conversion to unsigned
Some conversion requests to pmExtractValue(3) cannot be
performed based on the metric types and values involved, in
this case converting a negative value to an unsigned value.
PM_ERR_TYPE
Unknown or illegal metric type
The metric type is held in the metric descriptor and
sometimes encoded in the metric values returned from a call
to pmFetch(3). Legal values for the metric type are defined
by the PM_TYPE_* macros in <pcp/pmapi.h>.
PM_ERR_UNIT
Illegal pmUnits specification
Some conversion requests to pmConvScale(3) cannot be
performed due to illegal or incompatible specifications of
the source and destination units.
PM_ERR_PROFILE
Explicit instance identifier(s) required
Some PMDAs, especially the proc PMDA, will not return ``all
instances'' for a pmFetch(3) request due to the cost. The
client must explicitly built an instance profile using
pmAddProfile(3) and/or pmDelProfile(3) before calling
pmFetch(3). See also the -F/--fetchall option to pminfo(1).
PM_ERR_INST
Unknown or illegal instance identifier
A request to a PMDA nominates an instance that is unknown.
May occur as a consequence of the profile established prior
to a pmFetch(3) call, or an explicit instance name or
identifier to pmLookupInDom(3) or pmNameInDom(3).
PM_ERR_MODE
Illegal mode specification
Illegal mode argument to pmSetMode(3).
PM_ERR_PROFILESPEC
NULL pmInDom with non-NULL instlist
Bad arguments passed from a PCP client to pmAddProfile(3).
PM_ERR_TOOSMALL
Insufficient elements in list
Parameter passing error by caller specifying a list with less
than one element to pmFetch(3), pmLookupName(3) or
pmStore(3).
PM_ERR_FAULT
QA fault injected
For testing, there is a ``fault injection'' version of libpcp
and this error indicates a misuse of the fault injection
infrastructure.
PM_ERR_THREAD
Operation not supported for multi-threaded applications
As documented in PMAPI(3) and elsewhere, some libpcp routines
are intended solely for use from single-threaded
applications.
PM_ERR_NOCONTAINER
Container not found The user supplied container name does not
match any known container.
PM_ERR_BADSTORE
Bad input to pmstore
The metric value provided for a pmStore(3) operation is in
the wrong format, or of the wrong type or has the wrong
number of values.
PM_ERR_TOOBIG
Result size exceeded
Indicates a fatal error in the message (or PDU) passing
protocol between two PCP applications. This is an internal
error, and other than an exotic networking failure, should
not occur.
PM_ERR_RESET
PMCD reset or configuration change
Not used.
Refer to pmFetch(3) for an alternative mechanism that may be
used to notify a PCP client when pmcd(1) has experienced one
or more configuration changes since the last request from the
client. Usually these changes involve a change to the
namespace exported via pmcd and/or changes to the PMDAs under
pmcd's control.
PM_ERR_FAULT
QA fault injected
Used only for PCP Quality Assurance (QA) testing.
PM_ERR_NYI
Functionality not yet implemented
Self explanatory and rarely used.
PM_ERR_GENERIC
Generic error, already reported above
Rarely used, this error may be returned when the error
condition is a consequent of some earlier returned error and
a more precise characterization is not possible.
PM_ERR_BADDERIVE
Derived metric definition failed
When registering a derived metric, the metric expression is
either syntactically or semantically incorrect.
PM_ERR_NOLABELS
No support for metric label metadata
Operation requires metric labels, but none are available.
These errors may occur in the interactions between a PCP client
and pmcd(1) providing real-time performance data.
PM_ERR_NOAGENT
No PMCD agent for domain of request
A request sent to pmcd(1) requires information from an
agent or PMDA that does not exist. Usually this means the
namespace being used by the client application contains
metric names from a previously installed PMDA.
PM_ERR_CONNLIMIT
PMCD connection limit for this host exceeded
The client connection limit for pmcd(1) is controlled by
the optional access controls in $PCP_PMCDCONF_PATH. By
default there is no limit imposed by the PCP code, and
this error would not be seen.
PM_ERR_AGAIN
Try again. Information not currently available
Used to notify a PCP client that the PMDA responsible for
delivering the information is temporarily unavailable.
See also PM_ERR_PMDANOTREADY.
PM_ERR_NOPROFILE
Missing profile - protocol botch
Internal error in the communication between a client
application and pmcd(1) - should not occur.
PM_ERR_NEEDCLIENTCERT
PMCD requires a client certificate Authentication failure.
PM_ERR_PMDAFENCED
PMDA is currently fenced and unable to respond to requests
A privileged user has decided to isolate a PMDA from
pmcd(1) using a pmStore(1) operation on the
pmcd.agent.fenced metric, which means all fetch-level
requests to that PMDA are being blocked.
These errors may occur in the interactions between a PCP client
and the library routines that provide historical performance data
from PCP archives created by pmlogger(1).
PM_ERR_LOGFILE
Missing archive file
Each PCP archive consists of multiple physical files as
described in pmlogger(1). This error occurs when one of
the physical files is missing or cannot be opened for
reading.
PM_ERR_EOL
End of PCP archive
An attempt is made to read past the end file of the last
volume of a set of PCP archives, or past the end of the
time window (as specified with a -T/--finish option) for a
set of PCP archives.
PM_ERR_NOTHOST
Operation requires context with host source of metrics
Calls to pmStore(3) require a host context and are not
supported for PCP archives.
For archives created with versions of PCP prior to 4.0,
the pmLookupText(3) and pmLookupInDomText(3) calls will
return this code for archive PMAPI contexts (help and one-
line text was not previously recorded in archives).
PM_ERR_LOGREC
Corrupted record in a PCP archive
PCP archives can become corrupted for a variety of
reasons, but the most common is premature termination of
pmlogger(1) without flushing its output buffers.
PM_ERR_LABEL
Illegal label record at start of a PCP archive file
Each physical file in a PCP archive should begin with a
common label record. This is a special case of
PM_ERR_LOGREC errors.
PM_ERR_NODATA
Empty archive file
An empty physical file can never be part of a valid PCP
archive (at least the label record should be present).
This is a special case of PM_ERR_LOGREC errors.
PM_ERR_NOTARCHIVE
Operation requires context with archive source of metrics
A call to one of the archive variant routines, i.e.
pmFetchArchive(3), pmGetInDomArchive(3),
pmLookupInDomArchive(3) or pmNameInDomArchive(3), when the
current context is not associated with a set of PCP
archives.
PM_ERR_PMID_LOG
Metric not defined in the PCP archive
A PCP client has requested information about a metric, and
there is no corresponding information in the set of PCP
archives. This should not happen for well-behaved PCP
clients.
PM_ERR_INDOM_LOG
Instance domain identifier not defined in the PCP archive
A PCP client has requested information about an instance
domain for one or more performance metrics, and there is
no corresponding information in the set of PCP archives.
If the client is using metric descriptors from the set of
archives to identify the instance domain, this is less
likely to happen.
Because instance domains may vary over time, clients may
need to use the variant routines pmGetInDomArchive(3) or
pmLookupInDomArchive(3) or pmNameInDomArchive(3) to
manipulate the union of the instances in an instance
domain over the life of an archive.
PM_ERR_INST_LOG
Instance identifier not defined in the PCP archive
A PCP client has requested information about a specific
instance of a performance metric, and there is no
corresponding information in the set of PCP archives. If
the client is using instance names from the instance
domain in the set of archives (rather than hard-coded
instance names) and instance identifiers from the results
returned by pmFetch(3) or pmFetchArchive(3) this is less
likely to happen.
Because instance domains may vary over time, clients may
need to use the variant routines pmLookupInDomArchive(3)
or pmNameInDomArchive(3) to manipulate the union of the
instances in an instance domain over the life of an
archive.
PM_ERR_LOGOVERLAP
Archives overlap in time
When using a context associated with a set of archives,
the archives in the set may not overlap in time.
PM_ERR_LOGHOST
Archives differ by host
When using a context associated with a set of archives,
the archives in the set must all have been generated on
the same host.
PM_ERR_LOGCHANGETYPE
The type of a metric differs among archives
When using a context associated with a set of archives,
the type of each metric must be same in all of the
archives.
PM_ERR_LOGCHANGESEM
The semantics of a metric differs among archives
When using a context associated with a set of archives,
the semantics of each metric must be same in all of the
archives.
PM_ERR_LOGCHANGEINDOM
The instance domain of a metric differs among archives
When using a context associated with a set of archives,
the instance domain of each metric must be same in all of
the archives.
PM_ERR_LOGCHANGEUNITS
The units of a metric differs among archives
When using a context associated with a set of archives,
the units of each metric must be same in all of the
archives.
These errors may occur in the interactions between a GUI PCP
client and the time control services provided by pmtime(1).
PM_ERR_ISCONN
Already Connected
A PCP client application called pmTimeConnect(3) when
already connected to a pmtime(1) instance.
PM_ERR_NOTCONN
Not Connected
A PCP client application called one of the time control
routines pmTime*(3) when not currently connected to any
pmtime(1) instance.
PM_ERR_NEEDPORT
A non-null port name is required
If a shared pmtime(1) instance is being created the port
argument to pmTimeConnect(3) must not be invalid.
These errors may occur in the processing of PCP namespace
operations. A PCP namespace, see PMNS(5), provides the external
names and the internal identifiers for the available performance
metrics.
PM_ERR_NONLEAF
Metric name is not a leaf in PMNS
The metric name passed to pmLookupName(3) names a non-
terminal path in the namespace, i.e. a group of metrics
rather than a single metric.
PM_ERR_DUPPMNS
Attempt to reload the PMNS
When using an explicit local namespace, it is illegal to
call either of pmLoadNameSpace(3) or
pmLoadASCIINameSpace(3) more than once.
PM_ERR_PMNS
Problems parsing PMNS definitions
Only occurs when an ASCII namespace is explicitly loaded.
PM_ERR_NOPMNS
PMNS not accessible
Only occurs when an ASCII namespace is explicitly loaded.
These error codes are used in the interactions between pmcd(1)
and the PMDAs that provide the performance data.
PM_ERR_PMDANOTREADY
PMDA is not yet ready to respond to requests
Some PMDAs have long initialization or reset times, and
will respond to pmcd(1) with this error if they are busy
at the moment. This error translates to PM_ERR_AGAIN for
the PCP client who made the request to pmcd which caused
the initial request to the PMDA. At some later time the
PMDA will inform pmcd (see PM_ERR_PMDAREADY) that it is
now ready to process requests, and client requests will
begin to succeed.
PM_ERR_PMDAREADY
PMDA is now responsive to requests
Used by PMDAs to asynchronously inform pmcd(1) that they
are now willing to resume processing requests. See also
PM_ERR_PMDANOTREADY.
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). Values for these variables may be obtained
programmatically using the pmGetConfig(3) function.
PCPIntro(1), pmcd(1), pmerr(1), pminfo(1), pmtime(1), pmstore(1),
pmlogger(1), PMAPI(3), pmAddProfile(3), pmDelProfile(3),
pmConvScale(3), pmNewContext(3), pmDestroyContext(3),
pmErrStr(3), pmExtractValue(3), pmFetch(3), pmFetchArchive(3),
pmGetConfig(3), pmGetInDom(3), pmGetInDomArchive(3),
pmLoadNameSpace(3), pmLookupInDom(3), pmLookupInDomText(3),
pmLookupName(3), pmLookupText(3), pmNameInDom(3),
pmNameInDomArchive(3), pmSetMode(3), pmStore(3),
pmTimeConnect(3), pcp.conf(5), pcp.env(5) 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 PCPINTRO(3)
Pages that refer to this page: pmapi(3), pmierrstr(3), pmwebapi(3), pcp.conf(5), pcp.env(5), pmns(5)
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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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