pmrecord(3) — Linux manual page

NAME | C SYNOPSIS | DESCRIPTION | SEE ALSO | FILES | DIAGNOSTICS | COLOPHON

PMRECORD(3)             Library Functions Manual             PMRECORD(3)

NAME         top

       pmRecordSetup, pmRecordAddHost, pmRecordControl - record mode
       support for PMAPI clients

C SYNOPSIS         top

       #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

DESCRIPTION         top

       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 archive
       logs each created using a dedicated pmlogger(1) process, with an
       overall Archive Folio format as understood by pmafm(1), to name
       and collect all of the archive logs 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
           cannot 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 returned by pmGetProgname(3)).  If the application knows
           how to create its own configuration file to replay the
           recorded session, then replay should be non-zero.

           pmRecordSetup returns a stdio stream onto which the
           application should write the text of the required replay
           configuration file, if any.

       2.  For each host that is to be included in the recording
           session, call pmRecordAddHost.  A new pmRecordHost structure
           is returned via rhp.  It is assumed that pmcd(1) is running
           on host as this is how pmlogger(1) will retrieve the required
           performance 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
           configuration 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
           request 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 log.

       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
           session, 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
           pmRecordControl with a request of PM_REC_OFF.  If the rhp
           argument 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
           output 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
           identified 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
           processes 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
           pmlogger 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
           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
           output 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
       pmlogger 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 session.

       By default, information and dialogs from pmlogger will be
       displayed 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, because 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
       determined 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.

SEE ALSO         top

       pmafm(1), pmlogger(1), pmquery(1) and PMAPI(3).

FILES         top

       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
              configuration 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.

DIAGNOSTICS         top

       pmRecordSetup may return NULL in the event of an error.  Check
       errno for the real cause, but the value EINVAL typically means
       that the order of calls to these routines is not correct (there
       is obvious state associated with the current recording session
       that is maintained across calls to these routines).  For example
       the following calls would produce this EINVAL error; calling
       pmRecordControl before calling pmRecordAddHost at least once, or
       calling pmRecordAddHost 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.

COLOPHON         top

       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 pcp@groups.io.  This page was obtained from the
       project's upstream Git repository
       ⟨https://github.com/performancecopilot/pcp.git⟩ on 2021-04-01.
       (At that time, the date of the most recent commit that was found
       in the repository was 2021-04-01.)  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)