|
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. |
|
|
NAME | C SYNOPSIS | DESCRIPTION | DIAGNOSTICS | FILES | SEE ALSO | COLOPHON |
|
|
|
PMRECORD(3) Library Functions Manual PMRECORD(3)
pmRecordSetup, pmRecordAddHost, pmRecordControl - record mode
support for PMAPI clients
#include <pcp/pmafm.h>
FILE *pmRecordSetup(const char *folio, const char *creator,
int replay);
int pmRecordAddHost(const char *host, int isdefault,
pmRecordHost **rhp);
int pmRecordControl(pmRecordHost *rhp, int request,
const char *options);
cc ... -lpcp_gui
These routines may be used to create a Performance Co-Pilot (PCP)
archive ``on the fly'' to support ``record mode'' services for
PMAPI client applications.
Each record mode ``session'' involves one or more PCP archives
each created using a dedicated pmlogger(1) process, with an over‐
all Archive Folio format as understood by pmafm(1), to name and
collect all of the archives associated with a single recording
session.
The pmRecordHost structure is used to maintain state information
between the creator of the recording session and the associated
pmlogger process(es). The structure is defined as:
typedef struct {
FILE *f_config; /* caller writes pmlogger configuration here */
int fd_ipc; /* IPC channel to pmlogger */
char *logfile; /* full pathname for pmlogger error logfile */
pid_t pid; /* process id for pmlogger */
int status; /* exit status, -1 if unknown */
} pmRecordHost;
The routines are used in combination to create a recording session
as follows.
1. Call pmRecordSetup to establish a new recording session. A
new Archive Folio will be created using the name folio; if the
file or directory folio already exists, or the file folio can‐
not be created, this is an error. The application that is
creating the session is identified by creator (most often this
would be the same as the global PMAPI application name, as re‐
turned by pmGetProgname(3)). If the application knows how to
create its own configuration file to replay the recorded ses‐
sion, then replay should be non-zero.
pmRecordSetup returns a stdio stream onto which the applica‐
tion should write the text of the required replay configura‐
tion file, if any.
2. For each host that is to be included in the recording session,
call pmRecordAddHost. A new pmRecordHost structure is re‐
turned via rhp. It is assumed that pmcd(1) is running on host
as this is how pmlogger(1) will retrieve the required perfor‐
mance metrics.
If this host is the default host for this recording session,
then isdefault should be non-zero. This will ensure that the
corresponding archive appears first in the PCP archive folio,
and hence the tools used to replay the archive folio will make
the correct determination of the archive associated with the
default host. At most one host per recording session may be
nominated as the default host.
The calling application should write the desired pmlogger con‐
figuration onto the stdio stream returned via the f_config
field in the pmRecordHost structure.
3. Optionally add arguments to the command line that will be used
to launch pmlogger(1) by calling pmRecordControl with a re‐
quest of PM_REC_SETARG. The argument is passed via options
and one call to pmRecordControl is required for each distinct
argument.
An argument may be added for a particular pmlogger instance
identified by rhp, or if the rhp argument is NULL the argument
is added for all pmlogger instances that will be launched in
the current recording session.
Independent of any calls to pmRecordControl with a request of
PM_REC_SETARG, each pmlogger instance will automatically be
launched with the following arguments: -c, -h, -l, -x and the
basename for the PCP archive.
4. To commence the recording session, call pmRecordControl with a
request of PM_REC_ON, and rhp must be NULL. This will launch
one pmlogger(1) process for each host in the recording ses‐
sion, and initialize the fd_ipc, logfile, pid and status
fields in the associated pmRecordHost structure(s).
5. To terminate a pmlogger instance identified by rhp, call pm‐
RecordControl with a request of PM_REC_OFF. If the rhp argu‐
ment to pmRecordControl is NULL, the termination request is
broadcast to all pmlogger processes in the current recording
session.
An informative dialog is generated directly by each pmlogger
process and hence note the comments on the disposition of out‐
put from pmlogger below.
Alternatively, pmlogger can be started with options to limit
the duration of logging, e.g. the -T or -s arguments, in which
case there is no need to call pmRecordControl with a request
of PM_REC_OFF and no dialog is generated.
6. To display the current status of the pmlogger instance identi‐
fied by rhp, call pmRecordControl with a request of
PM_REC_STATUS. If the rhp argument to pmRecordControl is
NULL, the status request is broadcast to all pmlogger process‐
es in the current recording session.
The display is generated directly by each pmlogger process and
hence note the comments on the disposition of output from pm‐
logger below.
7. To detach a pmlogger instance identified by rhp and allow it
to continue independent of the application that launched the
recording session, call pmRecordControl with a request of
PM_REC_DETACH. If the rhp argument to pmRecordControl is
NULL, the detach request is broadcast to all pmlogger process‐
es in the current recording session.
An informative dialog is generated directly by each pmlogger
process and hence note the comments on the disposition of out‐
put from pmlogger below.
The calling application should not close any of the returned stdio
streams; this will be done by pmRecordControl when recording is
commenced.
Once pmlogger has been started for a recording session, then pm‐
logger will assume responsibility for any dialog with the user in
the event that the application that launched the recording session
should exit, particularly without terminating the recording ses‐
sion.
By default, information and dialogs from pmlogger will be dis‐
played using pmquery(1) on the assumption that most applications
wishing to launch a recording session are GUI-based. In the event
that pmquery fails to display the information (for example, be‐
cause the DISPLAY environment variable is not set), pmlogger will
write on its own stderr stream (not the stderr stream of the
launching process); the output will be assigned to the
XXXXXX.host.log file described in the FILES section below. For
convenience, the full pathname to this file is provided via the
logfile field in the pmRecordHost structure.
If the options argument to pmRecordControl is not NULL, this
string may be used to pass additional arguments to pmquery(1) in
those cases where a dialog is to be displayed. One use of this
capability would be to provide a -geometry string to control the
placement of the dialog.
Premature termination of a launched pmlogger process may be deter‐
mined using the pmRecordHost structure, by calling select(2) on
the fd_ipc field or polling the status field that will contain the
termination status from waitpid(2) if known, else -1.
pmRecordSetup may return NULL in the event of an error. Check er‐
rno for the real cause, but the value EINVAL typically means that
the order of calls to these routines is not correct (there is ob‐
vious state associated with the current recording session that is
maintained across calls to these routines). For example the fol‐
lowing calls would produce this EINVAL error; calling pmRecordCon‐
trol before calling pmRecordAddHost at least once, or calling pm‐
RecordAddHost before calling pmRecordSetup.
pmRecordControl and pmRecordAddHost both return 0 on success, else
a value less than 0 suitable for decoding with pmErrStr(3) on
failure. The value -EINVAL has the same interpretation as errno
being set to EINVAL as described above.
pmRecordControl will return PM_ERR_IPC if the associated pmlogger
process has already exited.
These routines create a number of files in the same directory as
the folio file named in the call to pmRecordSetup. In all cases,
the ``XXXXXX'' component is the result of calling mktemp(3).
XXXXXX If replay is non-zero, this is the creator's replay config‐
uration file, else an empty control file, used to guarantee
uniqueness.
folio The PCP Archive Folio, suitable for use with pmafm(1).
XXXXXX.host.config
The pmlogger(1) configuration for each host - if the same
host is used in different calls to pmRecordAddHost within
the same recording session then one of the letters ``a''
through ``z'' will be appended to the ``XXXXXX'' part of
all associated file names to ensure uniqueness.
XXXXXX.host.log
stdout and stderr for the pmlogger(1) instance for each
host.
XXXXXX.host.{0,meta,index}
The files comprising a single PCP archive for each host.
pmafm(1), pmlogger(1), pmquery(1) and PMAPI(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 PMRECORD(3)
Pages that refer to this page: pmafm(1)
|
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. |
|