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README.md

MPICH2 Release 1.4.1p1

MPICH2 is a high-performance and widely portable implementation of the MPI-2.2 standard from the Argonne National Laboratory. This release has all MPI 2.2 functions and features required by the standard with the exception of support for the "external32" portable I/O format and user-defined data representations for I/O.

The distribution has been tested by us on a variety of machines in our environments as well as our partner institutes. If you have problems with the installation or usage of MPICH2, please send an email to mpich-discuss@mcs.anl.gov (you need to subscribe to this list (https://lists.mcs.anl.gov/mailman/listinfo/mpich-discuss) before sending an email). If you have found a bug in MPICH2, we request that you report it at our bug tracking system: (https://trac.mcs.anl.gov/projects/mpich2/newticket).

This README file should contain enough information to get you started with MPICH2. More extensive installation and user guides can be found in the doc/installguide/install.pdf and doc/userguide/user.pdf files respectively. Additional information regarding the contents of the release can be found in the CHANGES file in the top-level directory, and in the RELEASE_NOTES file, where certain restrictions are detailed. Finally, the MPICH2 web site, http://www.mcs.anl.gov/research/projects/mpich2, contains information on bug fixes and new releases.

  1. Getting Started
  2. Compiler Flags
  3. Alternate Channels and Devices
  4. Alternate Process Managers
  5. Alternate Configure Options
  6. Testing the MPICH2 installation
  7. Fault Tolerance
  8. Environment Variables
  9. Developer Builds
  10. Installing MPICH2 on windows
  11. Multiple Fortran compiler support

  1. Getting Started ==================

The following instructions take you through a sequence of steps to get the default configuration (ch3 device, nemesis channel (with TCP and shared memory), Hydra process management) of MPICH2 up and running.

(a) You will need the following prerequisites.

- REQUIRED: This tar file mpich2-1.4.1p1.tar.gz

- REQUIRED: A C compiler (gcc is sufficient)

- OPTIONAL: A C++ compiler, if C++ applications are to be used
  (g++, etc.). If you do not require support for C++ applications,
  you can disable this support using the configure option
  --disable-cxx (configuring MPICH2 is described in step 1(d)
  below).

- OPTIONAL: A Fortran 77 compiler, if Fortran 77 applications are
  to be used (gfortran, ifort, etc.). If you do not require
  support for Fortran 77 applications, you can disable this
  support using --disable-f77 (configuring MPICH2 is described in
  step 1(d) below).

- OPTIONAL: A Fortran 90 compiler, if Fortran 90 applications are
  to be used (gfortran, ifort, etc.). If you do not require
  support for Fortran 90 applications, you can disable this
  support using --disable-fc. Note that Fortran 77 support is a
  prerequisite for Fortran 90 support (configuring MPICH2 is
  described in step 1(d) below).

Also, you need to know what shell you are using since different shell
has different command syntax. Command "echo $SHELL" prints out the
current shell used by your terminal program.

(b) Unpack the tar file and go to the top level directory:

  tar xzf mpich2-1.4.1p1.tar.gz
  cd mpich2-1.4.1p1

If your tar doesn't accept the z option, use

  gunzip mpich2-1.4.1p1.tar.gz
  tar xf mpich2-1.4.1p1.tar
  cd mpich2-1.4.1p1

(c) Choose an installation directory, say /home//mpich2-install, which is assumed to non-existent or empty. It will be most convenient if this directory is shared by all of the machines where you intend to run processes. If not, you will have to duplicate it on the other machines after installation.

(d) Configure MPICH2 specifying the installation directory:

for csh and tcsh:

  ./configure --prefix=/home/<USERNAME>/mpich2-install |& tee c.txt

for bash and sh:

  ./configure --prefix=/home/<USERNAME>/mpich2-install 2>&1 | tee c.txt

Bourne-like shells, sh and bash, accept "2>&1 |". Csh-like shell,
csh and tcsh, accept "|&". If a failure occurs, the configure
command will display the error. Most errors are straight-forward
to follow. For example, if the configure command fails with:

   "No Fortran 77 compiler found. If you don't need to build any
    Fortran programs, you can disable Fortran support using
    --disable-f77 and --disable-fc. If you do want to build
    Fortran programs, you need to install a Fortran compiler such
    as gfortran or ifort before you can proceed."

... it means that you don't have a Fortran compiler :-). You will
need to either install one, or disable Fortran support in MPICH2.

If you are unable to understand what went wrong, please go to step
1(i) below, for reporting the issue to the MPICH2 developers and
other users.

(e) Build MPICH2:

for csh and tcsh:

  make |& tee m.txt

for bash and sh:

  make 2>&1 | tee m.txt

This step should succeed if there were no problems with the
preceding step. Check file m.txt. If there were problems, do a
"make clean" and then run make again with V=1.

  make V=1 |& tee m.txt (for csh and tcsh)

  OR

  make V=1 2>&1 | tee m.txt (for bash and sh)

Then go to step 1(i) below, for reporting the issue to the MPICH2
developers and other users.

(f) Install the MPICH2 commands:

for csh and tcsh:

  make install |& tee mi.txt

for bash and sh:

  make install 2>&1 | tee mi.txt

This step collects all required executables and scripts in the bin
subdirectory of the directory specified by the prefix argument to
configure.

(g) Add the bin subdirectory of the installation directory to your path in your startup script (.bashrc for bash, .cshrc for csh, etc.):

for csh and tcsh:

  setenv PATH /home/<USERNAME>/mpich2-install/bin:$PATH

for bash and sh:

  PATH=/home/<USERNAME>/mpich2-install/bin:$PATH ; export PATH

Check that everything is in order at this point by doing:

  which mpicc
  which mpiexec

These commands should display the path to your bin subdirectory of
your install directory.

IMPORTANT NOTE: The install directory has to be visible at exactly
the same path on all machines you want to run your applications
on. This is typically achieved by installing MPICH2 on a shared
NFS file-system. If you do not have a shared NFS directory, you
will need to manually copy the install directory to all machines
at exactly the same location.

(h) MPICH2 uses a process manager for starting MPI applications. The process manager provides the "mpiexec" executable, together with other utility executables. MPICH2 comes packaged with multiple process managers; the default is called Hydra.

Now we will run an MPI job, using the mpiexec command as specified
in the MPI-2 standard. There are some examples in the install
directory, which you have already put in your path, as well as in
the directory mpich2-1.4.1p1/examples. One of them is the
classic CPI example, which computes the value of pi by numerical
integration in parallel.

To run the CPI example with 'n' processes on your local machine,
you can use:

  mpiexec -n <number> ./examples/cpi

Test that you can run an 'n' process CPI job on multiple nodes:

  mpiexec -f machinefile -n <number> ./examples/cpi

The 'machinefile' is of the form:

  host1
  host2:2
  host3:4 # Random comments
  host4:1

'host1', 'host2', 'host3' and 'host4' are the hostnames of the
machines you want to run the job on. The ':2', ':4', ':1' segments
depict the number of processes you want to run on each node. If
nothing is specified, ':1' is assumed.

More details on interacting with Hydra can be found at
http://wiki.mcs.anl.gov/mpich2/index.php/Using_the_Hydra_Process_Manager

If you have completed all of the above steps, you have successfully installed MPICH2 and run an MPI example.

(i) If you run into any errors configuring, building or running MPICH2, please send the below files to mpich-discuss@mcs.anl.gov. PLEASE COMPRESS BEFORE SENDING, AS THE FILES CAN BE LARGE. Note that, depending on which step the build failed, some of the files might not exist.

mpich2-1.4.1p1/c.txt (generated in step 1(d) above)
mpich2-1.4.1p1/m.txt (generated in step 1(e) above)
mpich2-1.4.1p1/mi.txt (generated in step 1(f) above)
mpich2-1.4.1p1/config.log (generated in step 1(d) above)
mpich2-1.4.1p1/src/openpa/config.log (generated in step 1(d) above)

More details on arguments to mpiexec are given in the User's Guide in the doc subdirectory.


  1. Compiler Flags =================

MPICH2 allows several sets of compiler flags to be used. The first three sets are configure-time options for MPICH2, while the fourth is only relevant when compiling applications with mpicc and friends.

(a) CFLAGS, CPPFLAGS, CXXFLAGS, FFLAGS, FCFLAGS, LDFLAGS and LIBS (abbreviated as xFLAGS): Setting these flags would result in the MPICH2 library being compiled/linked with these flags and the flags internally being used in mpicc and friends.

(b) MPICH2LIB_CFLAGS, MPICH2LIB_CPPFLAGS, MPICH2LIB_CXXFLAGS, MPICH2LIB_FFLAGS, MPICH2LIB_FCFLAGS, MPICH2LIB_LDFLAGS and MPICH2LIB_LIBS (abbreviated as MPICH2LIB_xFLAGS): Setting these flags would result in the MPICH2 library being compiled/linked with these flags. However, these flags will not be used by mpicc and friends.

(c) MPICH2_MAKE_CFLAGS: Setting these flags would result in MPICH2's configure tests to not use these flags, but the makefile's to use them. This is a temporary hack for certain cases that advanced developers might be interested in, but which break existing configure tests (e.g., -Werror). These are NOT recommended for regular users.

(d) MPICH2_MPICC_FLAGS, MPICH2_MPICPP_FLAGS, MPICH2_MPICXX_FLAGS, MPICH2_MPIF77_FLAGS, MPICH2_MPIFC_FLAGS, MPICH2_LDFLAGS and MPICH2_LIBS (abbreviated as MPICH2_MPIX_FLAGS): These flags do not affect the compilation of the MPICH2 library itself, but will be internally used by mpicc and friends.

+--------------------------------------------------------------------+ | | | | | | MPICH2 library | mpicc and friends | | | | | +--------------------+----------------------+------------------------+ | | | | | xFLAGS | Yes | Yes | | | | | +--------------------+----------------------+------------------------+ | | | | | MPICH2LIB_xFLAGS | Yes | No | | | | | +--------------------+----------------------+------------------------+ | | | | | MPICH2_MAKE_xFLAGS | Yes | No | | | | | +--------------------+----------------------+------------------------+ | | | | | MPICH2_MPIX_FLAGS | No | Yes | | | | | +--------------------+----------------------+------------------------+

All these flags can be set as part of configure command or through environment variables.

Default flags

By default, MPICH2 automatically adds certain compiler optimizations to MPICH2LIB_CFLAGS. The currently used optimization level is -O2.

** IMPORTANT NOTE: Remember that this only affects the compilation of the MPICH2 library and is not used in the wrappers (mpicc and friends) that are used to compile your applications or other libraries.

This optimization level can be changed with the --enable-fast option passed to configure. For example, to build an MPICH2 environment with -O3 for all language bindings, one can simply do:

./configure --enable-fast=O3

Or to disable all compiler optimizations, one can do:

./configure --disable-fast

For more details of --enable-fast, see the output of "configure --help".

Examples

Example 1:

./configure --disable-fast MPICH2LIB_CFLAGS=-O3 MPICH2LIB_FFLAGS=-O3
MPICH2LIB_CXXFLAGS=-O3 MPICH2LIB_FCFLAGS=-O3

This will cause the MPICH2 libraries to be built with -O3, and -O3 will not be included in the mpicc and other MPI wrapper script.

Example 2:

./configure --disable-fast CFLAGS=-O3 FFLAGS=-O3 CXXFLAGS=-O3 FCFLAGS=-O3

This will cause the MPICH2 libraries to be built with -O3, and -O3 will be included in the mpicc and other MPI wrapper script.

Example 3:

There are certain compiler flags that should not be used with MPICH2's configure, e.g. gcc's -Werror, which would confuse configure and cause certain configure tests to fail to detect the correct system features. To use -Werror in building MPICH2 libraries, you can pass the compiler flags during the make step through the Makefile variable MPICH2_MAKE_CFLAGS as follows:

make MPICH2_MAKE_CFLAGS="-Wall -Werror"

The content of MPICH2_MAKE_CFLAGS is appended to the CFLAGS in all relevant Makefiles.


  1. Alternate Channels and Devices =================================

The communication mechanisms in MPICH2 are called "devices". MPICH2 supports several internal devices including ch3 (default), dcmfd (for Blue Gene/P) and globus (for Globus), as well as many third-party devices that are released and maintained by other institutes such as osu_ch3 (from Ohio State University for InfiniBand and iWARP), ch_mx (from Myricom for Myrinet MX), etc.

               *************************************

ch3 device


The ch3 device contains different internal communication options called "channels". We currently support nemesis (default) and sock channels, and experimentally provide a dllchan channel within the ch3 device.

nemesis channel

Nemesis provides communication using different networks (tcp, mx) as well as various shared-memory optimizations. To configure MPICH2 with nemesis, you can use the following configure option:

--with-device=ch3:nemesis

The TCP network module gets configured in by default. To specify a different network module such as MX, you can use:

--with-device=ch3:nemesis:mx

If the MX include files and libraries are not in the normal search paths, you can specify them with the following options:

--with-mx-include= and --with-mx-lib=

... or the if lib/ and include/ are in the same directory, you can use the following option:

--with-mx=

If the MX libraries are shared libraries, they need to be in the shared library search path. This can be done by adding the path to /etc/ld.so.conf, or by setting the LD_LIBRARY_PATH variable in your .bashrc (or .tcshrc) file. It's also possible to set the shared library search path in the binary. If you're using gcc, you can do this by adding

LD_LIBRARY_PATH=/path/to/lib

(and)

LDFLAGS="-Wl,-rpath -Wl,/path/to/lib"

... as arguments to configure.

By default, MX allows for only eight endpoints per node causing ch3:nemesis:mx to give initialization errors with greater than 8 processes on the same node (this is an MX error and not an inherent limitation in the MPICH2/Nemesis design). If needed, this can be set to a higher number when MX is loaded. We recommend the user to contact help@myri.com for details on how to do this.

Shared-memory optimizations are enabled by default to improve performance for multi-processor/multi-core platforms. They can be disabled (at the cost of performance) either by setting the environment variable MPICH_NO_LOCAL to 1, or using the following configure option:

--enable-nemesis-dbg-nolocal

The --with-shared-memory= configure option allows you to choose how Nemesis allocates shared memory. The options are "auto", "sysv", and "mmap". Using "sysv" will allocate shared memory using the System V shmget(), shmat(), etc. functions. Using "mmap" will allocate shared memory by creating a file (in /dev/shm if it exists, otherwise /tmp), then mmap() the file. The default is "auto". Note that System V shared memory has limits on the size of shared memory segments so using this for Nemesis may limit the number of processes that can be started on a single node.

sock channel

sock is the traditional TCP sockets based communication channel. It uses TCP/IP sockets for all communication including intra-node communication. So, though the performance of this channel is worse than that of nemesis, it should work on almost every platform. This channel can be configured using the following option:

--with-device=ch3:sock

sctp channel

The SCTP channel is a new channel using the Stream Control Transmission Protocol (SCTP). This channel supports regular MPI-1 operations as well as dynamic processes and RMA from MPI-2; it currently does not offer support for multiple threads.

Configure the sctp channel by using the following option:

--with-device=ch3:sctp

If the SCTP include files and libraries are not in the normal search paths, you can specify them with the --with-sctp-include= and --with-sctp-lib= options, or the --with-sctp= option if lib/ and include/ are in the same directory.

SCTP stack specific instructions:

For FreeBSD 7 and onward, SCTP comes with CURRENT and is enabled with the "option SCTP" in the kernel configuration file. The sctp_xxx() calls are contained within libc so to compile ch3:sctp, make a soft-link named libsctp.a to the target libc.a, then pass the path of the libsctp.a soft-link to --with-sctp-lib.

For FreeBSD 6.x, kernel patches and instructions can be downloaded at http://www.sctp.org/download.html . These kernels place libsctp and headers in /usr, so nothing needs to be specified for --with-sctp since /usr is often in the default search path.

For Mac OS X, the SCTP Network Kernel Extension (NKE) can be downloaded at http://sctp.fh-muenster.de/sctp-nke.html . This places the lib and include in /usr, so nothing needs to be specified for --with-sctp since /usr is often in the default search path.

For Linux, SCTP comes with the default kernel from 2.4.23 and later as a module. This module can be loaded as root using "modprobe sctp". After this is loaded, you can verify it is loaded using "lsmod". Once loaded, the SCTP socket lib and include files must be downloaded and installed from http://lksctp.sourceforge.net/ . The prefix location must then be passed into --with-sctp. This bundle is called lksctp-tools and is available for download off their website.

For Solaris, SCTP comes with the default Solaris 10 kernel; the lib and include in /usr, so nothing needs to be specified for --with-sctp since /usr is often in the default search path. In order to compile under Solaris, MPICH2LIB_CFLAGS must have -DMPICH_SCTP_CONCATENATES_IOVS set when running MPICH2's configure script.

               *************************************

IBM Blue Gene/P device


MPICH2 also supports the IBM Blue Gene/P systems. Since BG/P's front-end uses a different architecture than the actual compute nodes, MPICH2 has to be cross-compiled for this platform. The configuration of MPICH2 on BG/P relies on the availability of the DCMF driver stack and cross compiler binaries on the system. These are packaged by IBM in their driver releases (default installation path is /bgsys/drivers/ppcfloor) and are not released with MPICH2.

Assuming DRIVER_PATH points to the driver installation path (e.g., /bgsys/drivers/ppcfloor), the following is an example configure command-line for MPICH2:

GCC=${DRIVER_PATH}/gnu-linux/bin/powerpc-bgp-linux-gcc
CC=${DRIVER_PATH}/gnu-linux/bin/powerpc-bgp-linux-gcc
CXX=${DRIVER_PATH}/gnu-linux/bin/powerpc-bgp-linux-g++
F77=${DRIVER_PATH}/gnu-linux/bin/powerpc-bgp-linux-gfortran
FC=${DRIVER_PATH}/gnu-linux/bin/powerpc-bgp-linux-gfortran
CFLAGS="-mcpu=450fp2"
CXXFLAGS="-mcpu=450fp2"
FFLAGS="-mcpu=450fp2"
FCFLAGS="-mcpu=450fp2"
AR=${DRIVER_PATH}/gnu-linux/bin/powerpc-bgp-linux-ar
LD=${DRIVER_PATH}/gnu-linux/bin/powerpc-bgp-linux-ld
MSGLAYER_INCLUDE="-I${DRIVER_PATH}/comm/include"
MSGLAYER_LIB="-L${DRIVER_PATH}/comm/lib -ldcmfcoll.cnk -ldcmf.cnk -lpthread -lrt
-L$DRIVER_PATH/runtime/SPI -lSPI.cna"
./configure --with-device=dcmfd:BGP --with-pmi=no --with-pm=no --with-file-system=bgl
--enable-timer-type=device --with-cross=src/mpid/dcmfd/cross
--host=powerpc-bgp-linux --target=powerpc-bgp-linux --build=powerpc64-linux-gnu


  1. Alternate Process Managers =============================

hydra

Hydra is the default process management framework that uses existing daemons on nodes (e.g., ssh, pbs, slurm, sge) to start MPI processes. More information on Hydra can be found at http://wiki.mcs.anl.gov/mpich2/index.php/Using_the_Hydra_Process_Manager

mpd

MPD was the traditional process manager in MPICH2. The file mpich2-1.4.1p1/src/pm/mpd/README has more information about interactive commands for managing the ring of MPDs. The MPD process manager is now deprecated.

smpd

SMPD is a process manager for interoperability between Microsoft Windows and UNIX, where some processes are running on Windows and others are running on a variant of UNIX. For more information, please see mpich2-1.4.1p1/src/pm/smpd/README.

gforker

gforker is a process manager that creates processes on a single machine, by having mpiexec directly fork and exec them. gforker is mostly meant as a research platform and for debugging purposes, as it is only meant for single-node systems.

slurm

SLURM is an external process manager not distributed with MPICH2. However, we provide configure options that allow integration with SLURM. To enable this support, use "--with-pmi=slurm --with-pm=no" option with configure.


  1. Alternate Configure Options ==============================

MPICH2 has a number of other features. If you are exploring MPICH2 as part of a development project, you might want to tweak the MPICH2 build with the following configure options. A complete list of configuration options can be found using:

./configure --help

However, for your convenience, we list a few important options here:

Performance Options:

--enable-fast - Turns off error checking and collection of internal timing information

--enable-timing=no - Turns off just the collection of internal timing information

--enable-ndebug - Turns on NDEBUG, which disables asserts. This is a subset of the optimizations provided by enable-fast, but is useful in environments where the user wishes to retain the debug symbols, e.g., this can be combined with the --enable-g option.

MPI Features:

--enable-romio - Build the ROMIO implementation of MPI-IO (enabled by default).

--with-file-system - When used with --enable-romio, specifies filesystems ROMIO should support. They can be specified by passing them in a '+'-delimited list: (e.g., --with-file-system="pvfs+nfs+ufs").

                   If you have installed version 2 of the PVFS
                   file system, you can use the
                   '--with-pvfs2=<prefix>' configure option to
                   specify where libraries, headers, and utilities
                   have been installed. If you have added the pvfs
                   utilities to your PATH, then ROMIO will detect
                   this and build support for PVFS automatically.

--enable-threads - Build MPICH2 with support for multi-threaded applications. Only the sock and nemesis channels support MPI_THREAD_MULTIPLE.

--with-thread-package - When used with --enable-threads, this option specifies the thread package to use. This option defaults to "posix". At the moment, only POSIX threads are supported on UNIX platforms. We plan to support Solaris threads in the future.

Language bindings:

--enable-f77 - Build the Fortran 77 bindings (enabled by default).

--enable-fc - Build the Fortran 90 bindings (enabled by default).

--enable-cxx - Build the C++ bindings (enabled by default).

Shared library support:

--enable-shared - Enable shared library support. Shared libraries are currently only supported for gcc (and gcc-like compilers) on Linux and Mac and for cc on Solaris. To have shared libraries created when MPICH2 is built, specify the following when MPICH2 is configured:

For users who wish to manually control the linker parameters, this can be done using:

--enable-sharedlibs=gcc (on Linux) --enable-sharedlibs=osx-gcc (on Mac OS X) --enable-sharedlibs=solaris-cc (on Solaris)

Cross compilation:

--with-cross=filename - Provide values for the tests that required running a program, such as the tests that configure uses to determine the sizes of the basic types. This should be a fine in Bourne shell format containing variable assignment of the form

                      CROSS_SIZEOF_INT=2

                      for all of the CROSS_xxx variables.

Error checking and reporting:

--enable-error-checking=level - Control the amount of error checking. Currently, only "no" and "all" is supported; all is the default.

--enable-error-messages=level - Control the aount of detail in error messages. By default, MPICH2 provides instance-specific error messages; but, with this option, MPICH2 can be configured to provide less detailed messages. This may be desirable on small systems, such as clusters built from game consoles or high-density massively parallel systems. This is still under active development.

Compilation options for development:

--enable-g=value - Controls the amount of debugging information collected by the code. The most useful choice here is dbg, which compiles with -g.

--enable-coverage - An experimental option that enables GNU coverage analysis.

--with-logging=name - Select a logging library for recording the timings of the internal routines. We have used this to understand the performance of the internals of MPICH2. More information on the logging options, capabilities and usage can be found in doc/logging/logging.pdf.

--enable-timer-type=name - Select the timer to use for MPI_Wtime and internal timestamps. name may be one of: gethrtime - Solaris timer (Solaris systems only) clock_gettime - Posix timer (where available) gettimeofday - Most Unix systems linux86_cycle - Linux x86; returns cycle counts, not time in seconds* linuxalpha_cycle - Like linux86_cycle, but for Linux Alpha* gcc_ia64_cycle - IPF ar.itc timer* device - The timer is provided by the device *Note that the cycle timers are intended to be used by MPICH2 developers for internal low-level timing. Normal users should not use these as they are not guaranteed to be accurate in certain situations.


  1. Testing the MPICH2 installation ==================================

To test MPICH2, we package the MPICH2 test suite in the MPICH2 distribution. You can run the test suite using:

 make testing

The results summary will be placed in test/summary.xml


  1. Fault Tolerance ==================

MPICH2 has some tolerance to process failures, and supports checkpointing and restart.

Tolerance to Process Failures

The features described in this section should be considered experimental. Which means that they have not been fully tested, and the behavior may change in future releases. The below notes are some guidelines on what can be expected in this feature:

  • ERROR RETURNS: Communication failures in MPICH2 are not fatal errors. This means that if the user sets the error handler to MPI_ERRORS_RETURN, MPICH2 will return an appropriate error code in the event of a communication failure. When a process detects a failure when communicating with another process, it will consider the other process as having failed and will no longer attempt to communicate with that process. The user can, however, continue making communication calls to other processes. Any outstanding send or receive operations to a failed process, or wildcard receives (i.e., with MPI_ANY_SOURCE) posted to communicators with a failed process, will be immediately completed with an appropriate error code.

  • COLLECTIVES: For collective operations performed on communicators with a failed process, the collective would return an error on some, but not necessarily all processes. A collective call returning MPI_SUCCESS on a given process means that the part of the collective performed by that process has been successful.

  • PROCESS MANAGER: If used with the hydra process manager, hydra will detect failed processes and notify the MPICH2 library. Users can query the list of failed processes using the MPICH_ATTR_FAILED_PROCESSES predefined attribute on MPI_COMM_WORLD. The attribute value is an integer array containing the ranks of the failed processes. The array is terminated by MPI_PROC_NULL.

    MPICH2 release specific note: The user needs to declare the
    following extern within the application in order to use the
    attribute (this ideally should be added to mpi.h, but has not
    been done so, to preserve ABI compatibility in the 1.3.x
    release series):
    
          extern int MPICH_ATTR_FAILED_PROCESSES;
    
    MPICH2 release specific note: The MPICH_ATTR_FAILED_PROCESSES
    attribute is currently only defined on MPI_COMM_WORLD, but not
    on other communicators.
    

    Note that hydra by default will abort the entire application when any process terminates before calling MPI_Finalize. In order to allow an application to continue running despite failed processes, you will need to pass the -disable-auto-cleanup option to mpiexec.

  • FAILURE NOTIFICATION: THIS IS AN UNSUPPORTED FEATURE AND WILL ALMOST CERTAINLY CHANGE IN THE FUTURE!

    In the current release, hydra notifies the MPICH2 library of failed processes by sending a SIGUSR1 signal. The application can catch this signal to be notified of failed processes. If the application replaces the library's signal handler with its own, the application must be sure to call the library's handler from it's own handler. Note that you cannot call any MPI function from inside a signal handler.

    In future releases, the plan is to provide a call such as MPIX_Failure_notify that will allow the user to register a callback function that will be called on process failures. This mechanism has not been added yet to preserve ABI compatibility in the 1.3.x release series.

Checkpoint and Restart

MPICH2 supports checkpointing and restart fault-tolerance using BLCR.

CONFIGURATION

First, you need to have BLCR version 0.8.2 or later installed on your machine. If it's installed in the default system location, add the following two options to your configure command:

--enable-checkpointing --with-hydra-ckpointlib=blcr

If BLCR is not installed in the default system location, you'll need to tell MPICH2's configure where to find it. You might also need to set the LD_LIBRARY_PATH environment variable so that BLCR's shared libraries can be found. In this case add the following options to your configure command:

--enable-checkpointing --with-hydra-ckpointlib=blcr --with-blcr=<BLCR_INSTALL_DIR> LD_LIBRARY_PATH=<BLCR_INSTALL_DIR>/lib

where <BLCR_INSTALL_DIR> is the directory where BLCR has been installed (whatever was specified in --prefix when BLCR was configured).

After it's configured compile as usual (e.g., make; make install).

Note, checkpointing is only supported with the Hydra process manager.

VERIFYING CHECKPOINTING SUPPORT

Make sure MPICH2 is correctly configured with BLCR. You can do this using:

mpiexec -info

This should display 'BLCR' under 'Checkpointing libraries available'.

CHECKPOINTING THE APPLICATION

There are two ways to cause the application to checkpoint. You can ask mpiexec to periodically checkpoint the application using the mpiexec option -ckpoint-interval (seconds):

mpiexec -ckpointlib blcr -ckpoint-prefix /tmp/app.ckpoint
-ckpoint-interval 3600 -f hosts -n 4 ./app

Alternatively, you can also manually force checkpointing by sending a SIGUSR1 signal to mpiexec.

The checkpoint/restart parameters can also be controlled with the environment variables HYDRA_CKPOINTLIB, HYDRA_CKPOINT_PREFIX and HYDRA_CKPOINT_INTERVAL.

To restart a process:

mpiexec -ckpointlib blcr -ckpoint-prefix /tmp/app.ckpoint -f hosts -n 4 -ckpoint-num

where is the checkpoint number you want to restart from.

These instructions can also be found on the MPICH2 wiki:

http://wiki.mcs.anl.gov/mpich2/index.php/Checkpointing


  1. Environment Variables ========================

MPICH2 provides several environment variables that have different purposes.

Generic Environment Variables

MPICH_NO_LOCAL - Disable shared-memory communication. With this option, even communication within a node will use the network stack.

           ************************************

MPICH_PORT_RANGE - Port range to use for MPICH2 internal TCP connections. This is useful when some of the host ports are blocked by a firewall. For example, setting MPICH_PORT_RANGE to "2000:3000" will ensure that MPICH2 will internally only uses ports between 2000 and 3000.

           ************************************

MPICH_ASYNC_PROGRESS - Initiates a spare thread to provide asynchronous progress. This improves progress semantics for all MPI operations including point-to-point, collective, one-sided operations and I/O. Setting this variable would increase the thread-safety level to MPI_THREAD_MULTIPLE. While this improves the progress semantics, it might cause a small amount of performance overhead for regular MPI operations.

           ************************************

MPICH_NAMEPUB_DIR - Allows the user to override where the publish and lookup information is placed for connect/accept based applications.


  1. Developer Builds =================== For MPICH2 developers who want to directly work on the svn, there are a few additional steps involved (people using the release tarballs do not have to follow these steps). Details about these steps can be found here: http://wiki.mcs.anl.gov/mpich2/index.php/Getting_And_Building_MPICH2

  1. Installing MPICH2 on Windows ================================

Here are the instructions for setting up MPICH2 on a Windows machine:

(a) Install: Microsoft Developer Studio 2003 or later Intel Fortran 8.0 or later cygwin choose the dos file format option install perl and cvs

(b) Checkout mpich2:

Bring up a command prompt.
(replace "yourname" with your MCS login name):
svn co https://svn.mcs.anl.gov/repos/mpi/mpich2/trunk mpich2

(c) Generate *.h.in

Bring up a cygwin bash shell.
cd mpich2
maint/updatefiles
exit

(d) Execute winconfigure.wsf

(e) Open Developer Studio

open mpich2\mpich2.sln
build the ch3sockDebug mpich2 solution
build the ch3sockDebug mpich2s project
build the ch3sockRelease mpich2 solution
build the ch3sockRelease mpich2s project
build the Debug mpich2 solution
build the Release mpich2 solution
build the fortDebug mpich2 solution
build the fortRelease mpich2 solution
build the gfortDebug mpich2 solution
build the gfortRelease mpich2 solution
build the sfortDebug mpich2 solution
build the sfortRelease mpich2 solution

(f) Open a command prompt

cd to mpich2\maint
execute "makegcclibs.bat"

(g) Open another Developer Studio instance

open mpich2\examples\examples.sln
build the Release target of the cpi project

(h) Return to Developer Studio with the mpich2 solution

set the version numbers in the Installer project
build the Installer mpich2 solution

(i) Test and distribute mpich2\maint\ReleaseMSI\mpich2.msi

mpich2.msi can be renamed, eg mpich2-1.1.msi

(j) To install the launcher:

Copy smpd.exe to a local directory on all the nodes.
Log on to each node as an administrator and execute "smpd.exe -install"

(k) Compile and run an MPI application:

Compile an mpi application. Use mpi.h from mpich2\src\include\win32
and mpi.lib in mpich2\lib

Place your executable along with the mpich2 dlls somewhere accessable
to all the machines.

Execute a job by running something like: mpiexec -n 3 myapp.exe

  1. Multiple Fortran compiler support =====================================

If the C compiler that is used to build MPICH2 libraries supports both multiple weak symbols and multiple aliases of common symbols, the Fortran 77 binding can support multiple Fortran compilers. The multiple weak symbols support allow MPICH2 to provide different name mangling scheme (of subroutine names) required by differen Fortran compilers. The multiple aliases of common symbols support enables MPICH2 to equal different common block symbols of the MPI Fortran constant, e.g. MPI_IN_PLACE, MPI_STATUS_IGNORE. So they are understood by different Fortran compilers.

Since the support of multiple aliases of common symbols is new/experimental, users can disable the feature by using configure option --disable-multi-aliases if it causes any undesirable effect, e.g. linker warnings of different sizes of common symbols, MPIFCMB* (the warning should be harmless).

We have only tested this support on a limited set of platforms/compilers. On linux, if the C compiler that builds MPICH2 is either gcc or icc, the above support will be enabled by configure. At the time of this writing, pgcc does not seem to have this multiple aliases of common symbols, so configure will detect the deficiency and disable the feature automatically. The tested Fortran compiler includes GNU Forran compilers(gfortan, g77), Intel Fortran compiler(ifort), Portland Group Fortran compilers(pgf77, pgf90), Absoft Fortran compilers (af77, af90), and IBM XL fortran compiler(xlf). What this mean is that if mpich2 is built by gcc/gfortran, the resulting mpich2 library can be used to link a Fortran program compiled/linked by another fortran compiler, say pgf77, say through mpif77 -f77=pgf77. As long as the Fortran program is linked without any errors by one of these compilers, the program shall be running fine.