README.envvar

(C) 2011 by Argonne National Laboratory.
    See COPYRIGHT in top-level directory.

This file lists the various environment variables available to change the
behavior of the MPICH2 library.  These are intended to be used by advanced
users.
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MPICH_ALLTOALL_SHORT_MSG_SIZE
    Aliases: MPIR_PARAM_ALLTOALL_SHORT_MSG_SIZE
    Description: the short message algorithm will be used if the
        per-destination message size (sendcount*size(sendtype)) is <= this
        value
    Default: 256

MPICH_ALLTOALL_MEDIUM_MSG_SIZE
    Aliases: MPIR_PARAM_ALLTOALL_MEDIUM_MSG_SIZE
    Description: the medium message algorithm will be used if the
        per-destination message size (sendcount*size(sendtype)) is <= this
        value and larger than ALLTOALL_SHORT_MSG_SIZE
    Default: 32768

MPICH_ALLTOALL_THROTTLE
    Aliases: MPIR_PARAM_ALLTOALL_THROTTLE
    Description: max no. of irecvs/isends posted at a time in some alltoall
        algorithms. Setting it to 0 causes all irecvs/isends to be posted
        at once.
    Default: 4

MPICH_REDSCAT_COMMUTATIVE_LONG_MSG_SIZE
    Aliases: MPIR_PARAM_REDSCAT_COMMUTATIVE_LONG_MSG_SIZE
    Description: the long message algorithm will be used if the operation
        is commutative and the send buffer size is >= this value (in bytes)
    Default: 524288

MPICH_BCAST_MIN_PROCS
    Aliases: MPIR_PARAM_BCAST_MIN_PROCS
    Description: the minimum number of processes in a communicator to use a
        non-binomial broadcast algorithm
    Default: 8

MPICH_BCAST_SHORT_MSG_SIZE
    Aliases: MPIR_PARAM_BCAST_SHORT_MSG_SIZE
    Description: the short message algorithm will be used if the send
        buffer size is < this value (in bytes)
    Default: 12288

MPICH_BCAST_LONG_MSG_SIZE
    Aliases: MPIR_PARAM_BCAST_LONG_MSG_SIZE
    Description: the long message algorithm will be used if the send buffer
        size is >= this value (in bytes)
    Default: 524288

MPICH_ALLGATHER_SHORT_MSG_SIZE
    Aliases: MPIR_PARAM_ALLGATHER_SHORT_MSG_SIZE
    Description: For MPI_Allgather and MPI_Allgatherv, the short message
        algorithm will be used if the send buffer size is < this value (in
        bytes).
    Default: 81920

MPICH_ALLGATHER_LONG_MSG_SIZE
    Aliases: MPIR_PARAM_ALLGATHER_LONG_MSG_SIZE
    Description: For MPI_Allgather and MPI_Allgatherv, the long message
        algorithm will be used if the send buffer size is >= this value (in
        bytes)
    Default: 524288

MPICH_REDUCE_SHORT_MSG_SIZE
    Aliases: MPIR_PARAM_REDUCE_SHORT_MSG_SIZE
    Description: the short message algorithm will be used if the send
        buffer size is <= this value (in bytes)
    Default: 2048

MPICH_ALLREDUCE_SHORT_MSG_SIZE
    Aliases: MPIR_PARAM_ALLREDUCE_SHORT_MSG_SIZE
    Description: the short message algorithm will be used if the send
        buffer size is <= this value (in bytes)
    Default: 2048

MPICH_GATHER_VSMALL_MSG_SIZE
    Aliases: MPIR_PARAM_GATHER_VSMALL_MSG_SIZE
    Description: use a temporary buffer for intracommunicator MPI_Gather if
        the send buffer size is < this value (in bytes)
    Default: 1024

MPICH_GATHER_INTER_SHORT_MSG_SIZE
    Aliases: MPIR_PARAM_GATHER_INTER_SHORT_MSG_SIZE
    Description: use the short message algorithm for intercommunicator
        MPI_Gather if the send buffer size is < this value (in bytes)
    Default: 2048

MPICH_GATHERV_INTER_SSEND_MIN_PROCS
    Aliases: MPIR_PARAM_GATHERV_INTER_SSEND_MIN_PROCS
             MPICH2_GATHERV_MIN_PROCS
    Description: Use Ssend (synchronous send) for intercommunicator
        MPI_Gatherv if the "group B" size is >= this value.  Specifying
        "-1" always avoids using Ssend.  For backwards compatibility,
        specifying "0" uses the default value.
    Default: 32

MPICH_SCATTER_INTER_SHORT_MSG_SIZE
    Aliases: MPIR_PARAM_SCATTER_INTER_SHORT_MSG_SIZE
    Description: use the short message algorithm for intercommunicator
        MPI_Scatter if the send buffer size is < this value (in bytes)
    Default: 2048

MPICH_ALLGATHERV_PIPELINE_MSG_SIZE
    Aliases: MPIR_PARAM_ALLGATHERV_PIPELINE_MSG_SIZE
    Description: The smallest message size that will be used for the
        pipelined, large-message, ring algorithm in the MPI_Allgatherv
        implementation.
    Default: 32768

MPICH_COMM_SPLIT_USE_QSORT
    Aliases: MPIR_PARAM_COMM_SPLIT_USE_QSORT
    Description: Use qsort(3) in the implementation of MPI_Comm_split
        instead of bubble sort.
    Default: 1

MPICH_NOLOCAL
    Aliases: MPICH_NO_LOCAL
             MPIR_PARAM_NOLOCAL
             MPIR_PARAM_NO_LOCAL
    Description: If true, force all processes to operate as though all
        processes are located on another node.  For example, this disables
        shared memory communication hierarchical collectives.
    Default: 0

MPICH_ODD_EVEN_CLIQUES
    Aliases: MPICH_EVEN_ODD_CLIQUES
             MPIR_PARAM_ODD_EVEN_CLIQUES
             MPIR_PARAM_EVEN_ODD_CLIQUES
    Description: If true, odd procs on a node are seen as local to each
        other, and even procs on a node are seen as local to each other. 
        Used for debugging on a single machine.
    Default: 0

MPICH_MEMDUMP
    Aliases: MPIR_PARAM_MEMDUMP
    Description: If true, list any memory that was allocated by MPICH2 and
        that remains allocated when MPI_Finalize completes.
    Default: 1

MPICH_PROCTABLE_SIZE
    Aliases: MPIR_PARAM_PROCTABLE_SIZE
    Description: Size of the "MPIR" debugger interface proctable (process
        table).
    Default: 64

MPICH_PROCTABLE_PRINT
    Aliases: MPIR_PARAM_PROCTABLE_PRINT
    Description: If true, dump the proctable entries at
        MPIR_WaitForDebugger-time. (currently compile-time disabled by "#if
        0")
    Default: 1

MPICH_ERROR_CHECKING
    Aliases: MPIR_PARAM_ERROR_CHECKING
    Description: If true, perform checks for errors, typically to verify
        valid inputs to MPI routines.  Only effective when MPICH2 is
        configured with --enable-error-checking=runtime .
    Default: 1

MPICH_PRINT_ERROR_STACK
    Aliases: MPIR_PARAM_PRINT_ERROR_STACK
    Description: If true, print an error stack trace at error handling
        time.
    Default: 1

MPICH_CHOP_ERROR_STACK
    Aliases: MPIR_PARAM_CHOP_ERROR_STACK
    Description: If >0, truncate error stack output lines this many
        characters wide.  If 0, do not truncate, and if <0 use a sensible
        default.
    Default: 0

MPICH_NEM_LMT_DMA_THRESHOLD
    Aliases: MPIR_PARAM_NEM_LMT_DMA_THRESHOLD
    Description: Messages larger than this size will use the "dma" (knem)
        intranode LMT implementation, if it is enabled and available.
    Default: 2097152

MPICH_NEMESIS_NETMOD
    Aliases: MPIR_PARAM_NEMESIS_NETMOD
    Description: If non-empty, this parameter specifies which network
        module should be used for communication.
    Default: ""

MPICH_INTERFACE_HOSTNAME
    Aliases: MPIR_PARAM_INTERFACE_HOSTNAME
    Description: If non-NULL, this parameter specifies the IP address that
        other processes should use when connecting to this process. This
        parameter is mutually exclusive with the MPICH_NETWORK_IFACE
        parameter and it is an error to set them both.
    Default: NULL

MPICH_NETWORK_IFACE
    Aliases: MPIR_PARAM_NETWORK_IFACE
    Description: If non-NULL, this parameter specifies which
        pseudo-ethernet interface the tcp netmod should use (e.g., "eth1",
        "ib0").  Note, this is a Linux-specific parameter. This parameter
        is mutually exclusive with the MPICH_INTERFACE_HOSTNAME parameter
        and it is an error to set them both.
    Default: NULL

MPICH_HOST_LOOKUP_RETRIES
    Aliases: MPIR_PARAM_HOST_LOOKUP_RETRIES
    Description: This parameter controls the number of times to retry the 
        gethostbyname() function before giving up.
    Default: 10

MPICH_DEBUG_HOLD
    Aliases: MPIR_PARAM_DEBUG_HOLD
    Description: If true, causes processes to wait in MPI_Init and
        MPI_Initthread for a debugger to be attached.  Once the debugger
        has attached, the variable 'hold' should be set to 0 in order to
        allow the process to continue (e.g., in gdb, "set hold=0").
    Default: 0

MPICH_ENABLE_CKPOINT
    Aliases: MPIR_PARAM_ENABLE_CKPOINT
    Description: If true, enables checkpointing support and returns an
        error if checkpointing library cannot be initialized.
    Default: 0

MPICH_ENABLE_COLL_FT_RET
    Aliases: MPIR_PARAM_ENABLE_COLL_FT_RET
    Description: Collectives called on a communicator with a failed process
        should not hang, however the result of the operation may be invalid
        even though the function returns MPI_SUCCESS.  This option enables
        an experimental feature that will return an error if the result of
        the collective is invalid.
    Default: 0

MPICH_ABORT_ON_LEAKED_HANDLES
    Aliases: MPIR_PARAM_ABORT_ON_LEAKED_HANDLES
    Description: If true, MPI will call MPI_Abort at MPI_Finalize if any
        MPI object handles have been leaked.  For example, if MPI_Comm_dup
        is called without calling a corresponding MPI_Comm_free.  For
        uninteresting reasons, enabling this option may prevent all known
        object leaks from being reported.  MPICH2 must have been configure
        with "--enable-g=handlealloc" or better in order for this
        functionality to work.
    Default: 0

MPICH_PORT_RANGE
    Aliases: MPICH_PORTRANGE
             MPIR_PARAM_PORT_RANGE
             MPIR_PARAM_PORTRANGE
    Description: "The MPICH_PORT_RANGE environment variable allows you to
        specify the range of TCP ports to be used by the process manager
        and the MPICH2 library. The format of this variable is
        <low>:<high>."
    Default: {0,0}

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Automatically generated
  by:   ./maint/genparams
  at:   Thu Sep  1 13:55:43 2011
  from: src/util/param/params.yml (md5sum 6d969dfaee560cd15ba5b677edcb1867)