SYNTAX

   C Syntax
          #include <mpi.h>

          int MPI_T_pvar_get_info(int pvar_index, char *name, int *name_len,
                                  int *verbosity, int *var_class, MPI_Datatype *datatype, MPI_T_enum *enumtype,
                                  char *desc, int *desc_len, int *bind, int *readonly, int *continuous,
                                  int *atomic)

INPUT PARAMETERS

       • pvar_index: Index of the performance variable to be queried.

INPUT/OUTPUT PARAMETERS

       • name_len: Length of the string and/or buffer for name.

       • desc_len: Length of the string and/or buffer for desc.

OUTPUT PARAMETERS

       • name: Buffer to return the string containing the name of the performance variable.

       • verbosity: Verbosity level of this variable.

       • var_class: Class of performance variable.

       • datatype: MPI datatype of the information stored in the performance variable.

       • enumtype: Optional descriptor for enumeration information.

       • desc: Buffer to return the string containing the description of the performance variable.

       • bind: Type of MPI object to which this variable must be bound.

       • readonly: Flag indicating whether the variable can be written/reset.

       • continuous: Flag indicating whether the variable can be started and stopped or is continuously active.

       • atomic: Flag indicating whether the variable can be atomically read and reset.

DESCRIPTION

       MPI_T_pvar_get_info  can  be  used to query information from a performance variable. The function returns
       the verbosity, class, datatype, enumeration type, and binding of the  queried  control  variable  in  the
       arguments  verbosity,  var_class, datatype, enumtype, and bind respectively. Flags indicating whether the
       variable is read-only, continuous, or atomic are returns in readonly, continuous, and atomic accordingly.
       See MPI-3 section 14.3.7 for more information. See the man page for MPI_T_cvar_get_info  for  information
       on variable verbosity.

VARIABLE CLASS

       Performance  variables  are categorized into classes which describe their initial value, valid types, and
       behavior. The class returned in the var_class parameter may be one of the following:

       • MPI_T_PVAR_CLASS_STATE: Variable represents a set of discrete  states  that  may  be  described  by  an
         enumerator.  Variables  of  this  class  must  be  represented by an MPI_INT. The starting value is the
         current state of the variable.

       • MPI_T_PVAR_CLASS_LEVEL: Variable represents the current utilization level of a resource.  Variables  of
         this  class  must  be  represented  by  an  MPI_UNSIGNED, MPI_UNSIGNED_LONG, MPI_UNSIGNED_LONG_LONG, or
         MPI_DOUBLE. The starting value is the current utilization level of the resource.

       • MPI_T_PVAR_CLASS_SIZE: Variable represents the fixed size of a resource. Variables of  this  class  are
         represented  by an MPI_UNSIGNED, MPI_UNSIGNED_LONG, MPI_UNSIGNED_LONG_LONG, or MPI_DOUBLE. The starting
         value is the current size of the resource.

       • MPI_T_PVAR_CLASS_PERCENTAGE:  Variable  represents  the  current  percentage  utilization  level  of  a
         resource.  Variables of this class are represented by an MPI_DOUBLE.  The starting value is the current
         percentage utilization of the resource.

       • MPI_T_PVAR_CLASS_HIGHWATERMARK: Variable  represents  the  high  watermark  of  the  utilization  of  a
         resource.   Variables   of   this   class   are  represented  by  an  MPI_UNSIGNED,  MPI_UNSIGNED_LONG,
         MPI_UNSIGNED_LONG_LONG, or MPI_DOUBLE. The starting value is the current utilization of the resource.

       • MPI_T_PVAR_CLASS_HIGHWATERMARK: Variable represents the low watermark of the utilization of a resource.
         Variables of this class are represented by an MPI_UNSIGNED, MPI_UNSIGNED_LONG,  MPI_UNSIGNED_LONG_LONG,
         or MPI_DOUBLE. The starting value is the current utilization of the resource.

       • MPI_T_PVAR_CLASS_COUNTER: Variable represents a count of the number of occurrences of a specific event.
         Variables    of    this   class   are   represented   by   an   MPI_UNSIGNED,   MPI_UNSIGNED_LONG,   or
         MPI_UNSIGNED_LONG_LONG. The starting value is 0.

       • MPI_T_PVAR_CLASS_COUNTER: Variable represents an aggregated value that represents a  sum  of  arguments
         processed  during  a  specific  event.  Variables  of  this  class  are represented by an MPI_UNSIGNED,
         MPI_UNSIGNED_LONG, MPI_UNSIGNED_LONG_LONG, or MPI_DOUBLE. The starting value is 0.

       • MPI_T_PVAR_CLASS_TIMER: Variable represents the aggregated time spent by the MPI  implementation  while
         processing  an  event, type of event, or section of code. Variables of this class are represented by an
         MPI_UNSIGNED, MPI_UNSIGNED_LONG, MPI_UNSIGNED_LONG_LONG, or MPI_DOUBLE. If the variable is  represented
         by an MPI_DOUBLE the units will be the same as those used by MPI_Wtime(). The starting value is 0.

       • MPI_T_PVAR_CLASS_GENERIC:  Variable  does  not  fit into any other class. Can by represented by an type
         supported by the MPI tool information interface (see DATATYPE).  Starting value is variable specific.

       For more information see MPI-3 section 14.3.7.

DATATYPE

       The datatype returned by MPI_T_pvar_get_info is restricted to one of the  following  datatypes:  MPI_INT,
       MPI_UNSIGNED,  MPI_UNSIGNED_LONG,  MPI_UNSIGNED_LONG_LONG,  MPI_COUNT, MPI_CHAR, and MPI_DOUBLE. For more
       information on datatypes in the MPI Tool information interface see MPI-3 section 14.3.5.

BINDING

       Performance variables may be bound to an MPI object. The binding returned in the bind  parameter  may  be
       one of the following:

       • MPI_T_BIND_NO_OBJECT: No object

       • MPI_T_BIND_MPI_COMM: MPI communicator

       • MPI_T_BIND_MPI_DATATYPE: MPI datatype

       • MPI_T_BIND_MPI_ERRHANDLER: MPI error handler

       • MPI_T_BIND_MPI_FILE: MPI file handle

       • MPI_T_BIND_MPI_GROUP: MPI group

       • MPI_T_BIND_MPI_OP: MPI reduction operator

       • MPI_T_BIND_MPI_REQUEST: MPI request

       • MPI_T_BIND_MPI_WIN: MPI window for one-sided communication

       • MPI_T_BIND_MPI_MESSAGE: MPI message object

       • MPI_T_BIND_MPI_INFO: MPI info object

       For more information see MPI-3 section 14.3.2.

NOTES

       This MPI tool interface function returns two strings. This function takes two argument for each string: a
       buffer  to  store  the  string,  and a length which must initially specify the size of the buffer. If the
       length passed is n then this function will copy at  most  n  -  1  characters  of  the  string  into  the
       corresponding buffer and set the length to the number of characters copied - 1. If the length argument is
       NULL  or the value specified in the length is 0 the corresponding string buffer is ignored and the string
       is not returned. For more information see MPI-3 section 14.3.3.

ERRORS

       MPI_T_pvar_get_info will fail if:

       • MPI_T_ERR_NOT_INITIALIZED: The MPI Tools interface not initialized

       • MPI_T_ERR_INVALID_INDEX: The performance variable index is invalid

       SEE ALSO:

          • MPI_T_cvar_get_info

COPYRIGHT

       2003-2025, The Open MPI Community

                                                  Feb 17, 2025                            MPI_T_PVAR_GET_INFO(3)