root/mpich2/branches/dev/kumudb/CHANGES @ 4870

===============================================================================
                               Changes in 1.1.1
===============================================================================

 # OVERALL: Improved support for Boost MPI.

 # PM/PMI: Improved startup time with MPD.

 # PM/PMI: Improved support for hybrid MPI-UPC program launching with
   Hydra.

 # PM/PMI: Improved support for process-core binding with Hydra.

 # PM/PMI: Preliminary support for PMI-2. Currently supported only
   with Hydra.

 # Many other bug fixes, memory leak fixes and code cleanup. A full
   list of changes is available using:

  svn log -r4655:HEAD https://svn.mcs.anl.gov/repos/mpi/mpich2/tags/release/mpich2-1.1.1

  ... or at the following link:

  https://trac.mcs.anl.gov/projects/mpich2/log/mpich2/tags/release/mpich2-1.1.1?action=follow_copy&rev=HEAD&stop_rev=4655&mode=follow_copy


===============================================================================
                               Changes in 1.1
===============================================================================

- OVERALL: Added MPI 2.1 support.

- OVERALL: Nemesis is now the default configuration channel with a
  completely new TCP communication module.

- OVERALL: Windows support for nemesis.

- OVERALL: Added a new Myrinet MX network module for nemesis.

- OVERALL: Initial support for shared-memory aware collective
  communication operations.  Currently MPI_Bcast, MPI_Reduce, MPI_Allreduce,
  and MPI_Scan.

- OVERALL: Improved handling of MPI Attributes.

- OVERALL: Support for BlueGene/P through the DCMF library (thanks to
  IBM for the patch).

- OVERALL: Experimental support for fine-grained multithreading

- OVERALL: Added dynamic processes support for Nemesis.

- OVERALL: Added automatic as well as statically runtime configurable
  receive timeout variation for MPD (thanks to OSU for the patch).

- OVERALL: Improved performance for MPI_Allgatherv, MPI_Gatherv, and MPI_Alltoall.

- PM/PMI: Initial support for the new Hydra process management
  framework (current support is for ssh, rsh, fork and a preliminary
  version of slurm).

- ROMIO: Added support for MPI_Type_create_resized and
  MPI_Type_create_indexed_block datatypes in ROMIO.

- ROMIO: Optimized Lustre ADIO driver (thanks to Weikuan Yu for
  initial work and Sun for further improvements).

- Many other bug fixes, memory leak fixes and code cleanup. A full
  list of changes is available using:

  svn log -r813:HEAD https://svn.mcs.anl.gov/repos/mpi/mpich2/tags/release/mpich2-1.1

  ... or at the following link:

  https://trac.mcs.anl.gov/projects/mpich2/log/mpich2/tags/release/mpich2-1.1?action=follow_copy&rev=HEAD&stop_rev=813&mode=follow_copy


===============================================================================
                               Changes in 1.0.7
===============================================================================

- OVERALL: Initial ROMIO device for BlueGene/P (the ADI device is also
added but is not configurable at this time).

- OVERALL: Major clean up for the propagation of user-defined and
other MPICH2 flags throughout the code.

- OVERALL: Support for STI Cell Broadband Engine.

- OVERALL: Added datatype free hooks to be used by devices
independently.

- OVERALL: Added device-specific timer support.

- OVERALL: make uninstall works cleanly now.

- ROMIO: Support to take hints from a config file

- ROMIO: more tests and bug fixes for nonblocking I/O

- PM/PMI: Added support to use PMI Clique functionality for process
managers that support it.

- PM/PMI: Added SLURM support to configure to make it transparent to
users.

- PM/PMI: SMPD Singleton Init support.

- WINDOWS: Fortran 90 support added.

- SCTP: Added MPICH_SCTP_NAGLE_ON support.

- MPE: Updated MPE logging API so that it is thread-safe (through
global mutex).

- MPE: Added infrastructure to piggyback argument data to MPI states.

- DOCS: Documentation creation now works correctly for VPATH builds.

- Many other bug fixes, memory leak fixes and code cleanup. A full
list of changes is available using:
  svn log -r100:HEAD https://svn.mcs.anl.gov/repos/mpi/mpich2/branches/release/MPICH2_1_0_7


===============================================================================
                               Changes in 1.0.6
===============================================================================

- Updates to the ch3:nemesis channel including preliminary support for
thread safety.

- Preliminary support for dynamic loading of ch3 channels (sock, ssm,
shm). See the README file for details.

- Singleton init now works with the MPD process manager.

- Fixes in MPD related to MPI-2 connect-accept.

- Improved support for MPI-2 generalized requests that allows true
nonblocking I/O in ROMIO.

- MPE changes:
  * Enabled thread-safe MPI logging through global mutex.
  * Enhanced Jumpshot to be more thread friendly
    + added simple statistics in the Legend windows.
  * Added backtrace support to MPE on Solaris and glibc based systems,
    e.g. Linux.  This improves the output error message from the 
    Collective/Datatype checking library.
  * Fixed the CLOG2 format so it can be used in serial (non-MPI) logging.

- Performance improvements for derived datatypes (including packing
and communication) through in-built loop-unrolling and buffer
alignment.

- Performance improvements for MPI_Gather when non-power-of-two
processes are used, and when a non-zero ranked root is performing the
gather.

- MPI_Comm_create works for intercommunicators.

- Enabled -O2 and equivalent compiler optimizations for supported
compilers by default (including GNU, Intel, Portland, Sun, Absoft,
IBM).

- Many other bug fixes, memory leak fixes and code cleanup. A full
list of changes is available at
www.mcs.anl.gov/mpi/mpich2/mpich2_1_0_6changes.htm.


===============================================================================
                               Changes in 1.0.5
===============================================================================

- An SCTP channel has been added to the CH3 device. This was
  implemented by Brad Penoff and Mike Tsai, Univ. of British Columbia.
  Their group's webpage is located at http://www.cs.ubc.ca/labs/dsg/mpi-sctp/ .

- Bugs related to dynamic processes have been fixed.

- Performance-related fixes have been added to derived datatypes and
  collective communication.

- Updates to the Nemesis channel

- Fixes to thread safety for the ch3:sock channel

- Many other bug fixes and code cleanup.  A full list of changes is available 
  at www.mcs.anl.gov/mpi/mpich2/mpich2_1_0_5changes.htm . 


===============================================================================
                               Changes in 1.0.4
===============================================================================

- For the ch3:sock channel, the default build of MPICH2 supports
  thread safety. A separate build is not needed as before. However, 
  thread safety is enabled only if the user calls MPI_Init_thread with  
  MPI_THREAD_MULTIPLE. If not, no thread locks are called, so there
  is no penalty.

- A new low-latency channel called Nemesis has been added. It can be
  selected by specifying the option --with-device=ch3:nemesis.
  Nemesis uses shared memory for intranode communication and various
  networks for internode communication.  Currently available networks
  are TCP, GM and MX.  Nemesis is still a work in progress.  See the
  README for more information about the channel.

- Support has been added for providing message queues to debuggers.
  Configure with --enable-debuginfo to make this information available.
  This is still a "beta" test version and has not been extensively tested.

- For systems with firewalls, the environment variable MPICH_PORT_RANGE can
  be used to restrict the range of ports used by MPICH2.  See the documentation
  for more details.

- Withdrew obsolete modules, including the ib and rdma communication layers.
  For Infiniband and MPICH2, please see 
  http://nowlab.cse.ohio-state.edu/projects/mpi-iba/ 
  For other interconnects, please contact us at mpich2-maint@mcs.anl.gov .

- Numerous bug fixes and code cleanup.  A full list of changes is available 
  at www.mcs.anl.gov/mpi/mpich2/mpich2_1_0_4changes.htm . 

- Numerous new tests in the MPICH2 test suite.

- For developers, the way in which information is passed between the top
  level configure and configures in the device, process management, and
  related modules has been cleaned up.  See the comments at the beginning
  of the top-level configure.in for details.  This change makes it easier
  to interface other modules to MPICH2.


===============================================================================
                               Changes in 1.0.3
===============================================================================

- There are major changes to the ch3 device implementation.  Old and 
  unsupported channels (essm, rdma) have been removed.   The
  internal interface between ch3 and the channels has been improved to 
  similify the process of adding a new channel (sharing existing code
  where possible) and to improve performance.  Further changes in this
  internal interface are expected.

- Numerous bug fixes and code cleanup

        Creation of intercommunicators and intracommunicators 
        from the intercommunicators created with Spawn and Connect/Accept

        The computation of the alignment and padding of items within
        structures now handles additional cases, including systems 
        where the alignment an padding depends on the type of the first
        item in the structure

        MPD recognizes wdir info keyword

        gforker's mpiexec supports -env and -genv arguments for controlling
        which environment variables are delivered to created processes

- While not a bug, to aid in the use of memory trace packages, MPICH2
  tries to free all allocated data no later than when MPI_Finalize
  returns.

- Support for DESTDIR in install targets

- Enhancements to SMPD

- In order to support special compiler flags for users that may be
  different from those used to build MPICH2, the environment variables
  MPI_CFLAGS, MPI_FFLAGS, MPI_CXXFLAGS, and MPI_F90FLAGS may be used
  to specify the flags used in mpicc, mpif77, mpicxx, and mpif90 
  respectively.  The flags CFLAGS, FFLAGS, CXXFLAGS, and F90FLAGS are
  used in the building of MPICH2.

- Many enhancements to MPE

- Enhanced support for features and idiosyncracies of Fortran 77 and 
  Fortran 90 compilers, including gfortran, g95, and xlf

- Enhanced support for C++ compilers that do not fully support abstract
  base classes

- Additional tests in the mpich2/tests/mpi
    
- New FAQ included (also available at
    http://www.mcs.anl.gov/mpi/mpich2/faq.htm) 

- Man pages for mpiexec and mpif90

- Enhancements for developers, including a more flexible and general 
  mechanism for inserting logging and information messages, controlable
  with --mpich-dbg-xxx command line arguments or MPICH_DBG_XXX environment
  variables.

- Note to developers: 
  This release contains many changes to the structure of the CH3
  device implementation (in src/mpid/ch3), including signficant
  reworking of the files (many files have been combined into fewer files
  representing logical grouping of functions).  The next release of 
  MPICH2 will contain even more significant changes to the device 
  structure as we introduce a new communication implementation.
 
===============================================================================
                               Changes in 1.0.2
===============================================================================

- Optimizations to the MPI-2 one-sided communication functions for the
  sshm (scalable shared memory) channel when window memory is
  allocated with MPI_Alloc_mem (for all three synchronization methods).

- Numerous bug fixes and code cleanup. 

- Fixed memory leaks.

- Fixed shared library builds.

- Fixed performance problems with MPI_Type_create_subarray/darray 

- The following changes have been made to MPE2:

  - MPE2 now builds the MPI collective and datatype checking library
    by default. 

  - SLOG-2 format has been upgraded to 2.0.6 which supports event drawables
    and provides count of real drawables in preview drawables.

  - new slog2 tools, slog2filter and slog2updater, which both are logfile
    format convertors.  slog2filter removes undesirable categories of
    drawables as well as alters the slog2 file structure.  slog2updater
    is a slog2filter that reads in older logfile format, 2.0.5, and 
    writes out the latest format 2.0.6.

- The following changes have been made to MPD:

  - Nearly all code has been replaced by new code that follows a more
    object-oriented approach than before.  This has not changed any
    fundamental behavior or interfaces.

  - There is info support in spawn and spawn_multiple for providing
    parts of the environment for spawned processes such as search-path
    and current working directory.  See the Standard for the required
    fields.

  - mpdcheck has been enhanced to help users debug their cluster and
    network configurations.

  - CPickle has replaced marshal as the source module for dumps and loads.

  - The mpigdb command has been replaced by mpiexec -gdb.

  - Alternate interfaces can be used.  See the Installer's Guide.
 

===============================================================================
                               Changes in 1.0.1
===============================================================================

- Copyright statements have been added to all code files, clearly identifying
  that all code in the distribution is covered by the extremely flexible
  copyright described in the COPYRIGHT file.

- The MPICH2 test suite (mpich2/test) can now be run against any MPI
  implementation, not just MPICH2.

- The send and receive socket buffers sizes may now be changed by setting
  MPICH_SOCKET_BUFFER_SIZE.  Note: the operating system may impose a maximum
  socket buffer size that prohibits MPICH2 from increasing the buffers to the
  desire size.  To raise the maximum allowable buffer size, please contact your
  system administrator.

- Error handling throughout the MPI routines has been improved.  The error
  handling in some internal routines has been simplified as well, making the
  routines easier to read.

- MPE (Jumpshot and CLOG logging) is now supported on Microsoft Windows.

- C applications built for Microsoft Windows may select the desired channels at
  runtime.

- A program not started with mpiexec may become an MPI program by calling
  MPI_Init.  It will have an MPI_COMM_WORLD of size one.  It may then call
  other MPI routines, including MPI_COMM_SPAWN, to become a truly parallel
  program.  At present, the use of MPI_COMM_SPAWN and MPI_COMM_SPAWN_MULTIPLE
  by such a process is only supported by the MPD process manager.

- Memory leaks in communicator allocation and the C++ binding have been fixed.

- Following GNU guidelines, the parts of the install step that checked the
  installation have been moved to an installcheck target.  Much of the
  installation now supports the DESTDIR prefix.

- Microsoft Visual Studio projects have been added to make it possible to build
  x86-64 version

- Problems with compilers and linkers that do not support weak symbols, which
  are used to support the PMPI profiling interface, have been corrected.

- Handling of Fortran 77 and Fortran 90 compilers has been improved, including
  support for g95.

- The Fortran stdcall interface on Microsoft Windows now supports character*.

- A bug in the OS X implementation of poll() caused the sock channel to hang.
  A workaround has been put in place.

- Problems with installation under OS/X are now detected and corrected.
  (Install breaks libraries that are more than 10 seconds old!)

- The following changes have been made to MPD:

  - Sending a SIGINT to mpiexec/mpdrun, such as by typing control-C, now causes
    SIGINT to be sent to the processes within the job.  Previously, SIGKILL was
    sent to the processes, preventing applications from catching the signal 
    and performing their own signal processing.

  - The process for merging output has been improved.

  - A new option, -ifhn, has been added to the machine file, allowing the user
    to select the destination interface to be used for TCP communication.  See
    the User's Manual for details.

  - The user may now select, via the "-s" option to mpiexec/mpdrun, which
    processes receive input through stdin.  stdin is immediately closed for all
    processes not in set receiving input.  This prevents processes not in the
    set from hanging should they attempt to read from stdin.

  - The MPICH2 Installer's Guide now contains an appendix on troubleshooting
    problems with MPD.

- The following changes have been made to SMPD:

  - On Windows machines, passwordless authentication (via SSPI) can now be used
    to start processes on machines within a domain.  This feature is a recent
    addition, and should be considered experimental.

  - On Windows machines, the -localroot option was added to mpiexec, allowing
    processes on the local machines to perform GUI operations on the local
    desktop.

  - On Windows machines, network drive mapping is now supported via the -map
    option to mpiexec.

  - Three new GUI tools have been added for Microsoft Windows.  These tools are
    wrappers to the command line tools, mpiexec.exe and smpd.exe.  wmpiexec
    allows the user to run a job much in the way they with mpiexec.  wmpiconfig
    provides a means of setting various global options to the SMPD process
    manager environment.  wmpiregister encrypts the user's credentials and
    saves them to the Windows Registry.

- The following changes have been made to MPE2:

  - MPE2 no longer attempt to compile or link code during 'make install' to
    validate the installation.  Instead, 'make installcheck' may now be used to
    verify that the MPE installation.

  - MPE2 now supports DESTDIR.

- The sock channel now has preliminary support for MPI_THREAD_SERIALIZED and
  MPI_THREAD_MULTIPLE on both UNIX and Microsoft Windows.  We have performed
  rudimentary testing; and while overall the results were very positive, known
  issues do exist.  ROMIO in particular experiences hangs in several places.
  We plan to correct that in the next release.  As always, please report any
  difficulties you encounter.

- Another channel capable of communicating with both over sockets and shared
  memory has been added.  Unlike the ssm channel which waits for new data to
  arrive by continuously polling the system in a busy loop, the essm channel
  waits by blocking on an operating system event object.  This channel is
  experimental, and is only available for Microsoft Windows.

- The topology routines have been modified to allow the device to override the
  default implementation.  This allows the device to export knowledge of the
  underlying physical topology to the MPI routines (Dims_create and the
  reorder == true cases in Cart_create and Graph_create).  

- New memory allocation macros, MPIU_CHK[PL]MEM_*(), have been added to help
  prevent memory leaks.  See mpich2/src/include/mpimem.h.

- New error reporting macros, MPIU_ERR_*, have been added to simplify the error
  handling throughout the code, making the code easier to read.  See
  mpich2/src/include/mpierrs.h.

- Interprocess communication using the Sock interface (sock and ssm channels)
  may now be bound to a particular destination interface using the environment
  variable MPICH_INTERFACE_HOSTNAME.  The variable needs to be set for each
  process for which the destination interface is not the default interface.
  (Other mechanisms for destination interface selection will be provided in
  future releases.)  Both MPD and SMPD provide a more simplistic mechanism for
  specifying the interface.  See the user documentation.

- Too many bug fixes to describe.  Much thanks goes to the users who reported
  bugs.  Their patience and understanding as we attempted to recreate the
  problems and solve them is greatly appreciated.


===============================================================================
                                Changes in 1.0
===============================================================================

- MPICH2 now works on Solaris.

- The User's Guide has been expanded considerably.  The Installation Guide has
  been expanded some as well.

- MPI_COMM_JOIN has been implemented; although like the other dynamic process
  routines, it is only supported by the Sock channel.

- MPI_COMM_CONNECT and MPI_COMM_ACCEPT are now allowed to connect with remote
  process to which they are already connected.

- Shared libraries can now be built (and used) on IA32 Linux with the GNU
  compilers (--enable-sharedlibs=gcc), and on Solaris with the native Sun
  Workshop compilers (--enable-sharedlibs=solaris).  They may also work on
  other operating systems with GCC, but that has not been tested.  Previous
  restrictions disallowing C++ and Fortran bindings when building shared
  libraries have been removed.

- The dataloop and datatype contents code has been improved to address
  alignment issues on all platforms.

- A bug in the datatype code, which handled zero block length cases
  incorrectly, has been fixed.

- An segmentation fault in the datatype memory management, resulting from
  freeing memory twice, has been fixed.

- The following changes were made to the MPD process manager:

  - MPI_SPAWN_MULTIPLE now works with MPD.

  - The arguments to the 'mpiexec' command supplied by the MPD have changed.
    First, the -default option has been removed.  Second, more flexible ways to
    pass environment variables have been added.

  - The commands 'mpdcheck' and 'testconfig' have been to installations using
    MPD.  These commands test the setup of the machines on which you wish to
    run MPICH2 jobs.  They help to identify misconfiguration, firewall issues,
    and other communication problems.

  - Support for MPI_APPNUM and MPI_UNIVERSE_SIZE has been added to the Simple
    implementation of PMI and the MPD process manager.

  - In general, error detection and recovery in MPD has improved.

- A new process manager, gforker, is now available.  Like the forker process
  manager, gforker spawns processes using fork(), and thus is quite useful on
  SMPs machines.  However, unlike forker, gforker supports all of the features
  of a standard mpiexec, plus some.  Therefore, It should be used in place of
  the previous forker process manager, which is now deprecated.

- The following changes were made to ROMIO:

  - The amount of duplicated ROMIO code in the close, resize, preallocate,
    read, write, asynchronous I/O, and sync routines has been substantially
    reduced.

  - A bug in flattening code, triggered by nested datatypes, has been fixed.

  - Some small memory leaks have been fixed.

  - The error handling has been abstracted allowing different MPI
    implementations to handle and report error conditions in their own way.
    Using this abstraction, the error handling routines have been made
    consistent with rest of MPICH2.

  - AIO support has been cleaned up and unified.  It now works correctly on
    Linux, and is properly detected on old versions of AIX.

  - A bug in MPI_File_seek code, and underlying support code, has been fixed.

  - Support for PVFS2 has improved.

  - Several dead file systems have been removed.  Others, including HFS, SFS,
    PIOFS, and Paragon, have been deprecated.

- MPE and CLOG have been updated to version 2.1. For more details, please see
  src/mpe2/README.

- New macros for memory management were added to support function local
  allocations (alloca), to rollback pending allocations when error conditions
  are detected to avoid memory leaks, and to improve the conciseness of code
  performing memory allocations.

- New error handling macros were added to make internal error handling code
  more concise.

===============================================================================
                               Changes in 0.971
===============================================================================

- Code restricted by copyrights less flexible than the one described in the
  COPYRIGHT file has been removed.

- Installation and User Guides have been added.

- The SMPD PMI Wire Protocol Reference Manual has been updated.

- To eliminate portability problems, common blocks in mpif.h that spanned
  multiple lines were broken up into multiple common blocks each described on a
  single line.

- A new command, mpich2version, was added to allow the user to obtain
  information about the MPICH2 installation.  This command is currently a
  simple shell script.  We anticipate that the mpich2version command will
  eventually provide additional information such as the patches applied and the
  date of the release.

- The following changes were made to MPD2:

  - Support was added for MPI's "singleton init", in which a single
    process started in the normal way (i.e., not by mpiexec or mpirun)
    becomes an MPI process with an MPI_COMM_WORLD of size one by
    calling MPI_Init.  After this the process can call other MPI
    functions, including MPI_Comm_spawn.

  - The format for some of the arguments to mpiexec have changed,
    especially for passing environment variables to MPI processes.

  - In addition to miscellaneous hardening, better error checking and
    messages have been added.

  - The install process has been improved.  In particular, configure
    has been updated to check for a working install program and supply
    it's own installation script (install.sh) if necessary.

  - A new program, mpdcheck, has been added to help diagnose machine
    configurations that might be erroneous or at least confusing to
    mpd.

  - Runtime version checking has been added to insure that the Simple
    implementation of PMI linked into the application and the MPD
    process manager being used to run that application are compatible.

  - Minor improvements have been made to mpdboot.

  - Support for the (now deprecated) BNR interface has been added to
    allow MPICH1 programs to also be run via MPD2.

- Shared libraries are now supported on Linux systems using the GNU compilers
  with the caveat that C++ support must be disabled (--disable-cxx).

- The CH3 interface and device now provide a mechanism for using RDMA (remote
  direct memory access) to transfer data between processes.

- Logging capabilities for MPI and internal routines have been readded.  See
  the documentation in doc/logging for details.

- A "meminit" option was added to --enable-g to force all bytes associated with
  a structure or union to be initialized prior to use.  This prevents programs
  like Valgrind from complaining about uninitialized accesses.

- The dist-with-version and snap targets in the top-level Makefile.sm now
  properly produce mpich2-<ver>/maint/Version instead of mpich2-<ver>/Version.
  In addition, they now properly update the VERSION variable in Makefile.sm
  without clobbering the sed line that performs the update.

- The dist and snap targets in the top-level Makefile.sm now both use the
  dist-with-version target to avoid inconsistencies.

- The following changes were made to simplemake:

  - The environment variables DEBUG, DEBUG_DIRS, and DEBUG_CONFDIR can now be
    used to control debugging output.

  - Many fixes were made to make simplemake so that it would run cleanly with
    perl -w.

  - Installation of *all* files from a directory is now possible (example,
    installing all of the man pages).

  - The clean targets now remove the cache files produced by newer versions of
    autoconf.

  - For files that are created by configure, the determination of the
    location of that configure has been improved, so that make of those
    files (e.g., make Makefile) is more likely to work.  There is still 
    more to do here.

  - Short loops over subdirectories are now unrolled.

  - The maintainerclean target has been renamed to maintainer-clean to match
    GNU guidelines.

  - The distclean and maintainer-clean targets have been improved.

  - An option was added to perform one ar command per directory instead of one
    per file when creating the profiling version of routines (needed only for
    systems that do not support weak symbols).


===============================================================================
                                Changes in 0.97
===============================================================================

- MPI-2 one-sided communication has been implemented in the CH3 device.

- mpigdb works as a simple parallel debugger for MPI programs started
  with mpd.  New since MPICH1 is the ability to attach to running
  parallel programs.  See the README in mpich2/src/pm/mpd for details.

- MPI_Type_create_darray() and MPI_Type_create_subarray() implemented including
  the right contents and envelope data.

- ROMIO flattening code now supports subarray and darray combiners.

- Improve scalability and performance of some ROMIO PVFS and PVFS2 routines 

- An error message string parameter was added to MPID_Abort().  If the
  parameter is non-NULL this string will be used as the message with the abort
  output.  Otherwise, the output message will be base on the error message
  associated with the mpi_errno parameter.

- MPID_Segment_init() now takes an additional boolean parameter that specifies
  if the segment processing code is to produce/consume homogeneous (FALSE) or
  heterogeneous (TRUE) data.

- The definitions of MPID_VCR and MPID_VCRT are now defined by the device.

- The semantics of MPID_Progress_{Start,Wait,End}() have changed.  A typical
  blocking progress loop now looks like the following.

  if (req->cc != 0)
  {
      MPID_Progress_state progress_state;

      MPID_Progress_start(&progress_state);
      while (req->cc != 0)
      {
          mpi_errno = MPID_Progress_wait(&progress_state);
          if (mpi_errno != MPI_SUCCESS)
          {
              /* --BEGIN ERROR HANDLING-- */
              MPID_Progress_end(&progress_state);
              goto fn_fail;
              /* --END ERROR HANDLING-- */
          }
      }
      MPID_Progress_end(&progress_state);
  }

  NOTE: each of these routines now takes a single parameter, a pointer to a
  thread local state variable.

- The CH3 device and interface have been modified to better support
  MPI_COMM_{SPAWN,SPAWN_MULTIPLE,CONNECT,ACCEPT,DISCONNECT}.  Channels
  writers will notice the following.  (This is still a work in progress.  See
  the note below.)

  - The introduction of a process group object (MPIDI_PG_t) and a new
    set of routines to manipulate that object.

  - The renaming of the MPIDI_VC object to MPIDI_VC_t to make it more
    consistent with the naming of other objects in the device.

  - The process group information in the MPIDI_VC_t moved from the channel
    specific portion to the device layer.

  - MPIDI_CH3_Connection_terminate() was added to the CH3 interface to allow
    the channel to properly shutdown a connection before the device deletes all
    associated data structures.

  - A new upcall routine, MPIDI_CH3_Handle_connection(), was added to allow the
    device to notify the device when a connection related event has completed.
    A present the only event is MPIDI_CH3_VC_EVENT_TERMINATED, which notify the
    device that the underlying connection associated with a VC has been
    properly shutdown.  For every call to MPIDI_CH3_Connection_terminate() that
    the device makes, the channel must make a corresponding upcall to
    MPIDI_CH3_Handle_connection().  MPID_Finalize() will likely hang if this
    rule is not followed.

  - MPIDI_CH3_Get_parent_port() was added to provide MPID_Init() with the port
    name of the the parent (spawner).  This port name is used by MPID_Init()
    and MPID_Comm_connect() to create an intercommunicator between the parent
    (spawner) and child (spawnee).  Eventually, MPID_Comm_spawn_multiple() will
    be update to perform the reverse logic; however, the logic is presently
    still in the sock channel.

  Note: the changes noted are relatively fresh and are the beginning to a set
  of future changes.  The goal is to minimize the amount of code required by a
  channel to support MPI dynamic process functionality.  As such, portions of
  the device will change dramatically in a future release.  A few more changes
  to the CH3 interface are also quite likely.

- MPIDI_CH3_{iRead,iWrite}() have been removed from the CH3 interface.
  MPIDI_CH3U_Handle_recv_pkt() now returns a receive request with a populated
  iovec to receive data associated with the request.
  MPIDU_CH3U_Handle_{recv,send}_req() reload the iovec in the request and
  return and set the complete argument to TRUE if more data is to read or
  written.  If data transfer for the request is complete, the complete argument
  must be set to FALSE.


=============================================================================== 
                               Changes in 0.96p2
===============================================================================

The shm and ssm channels have been added back into the distribution.
Officially, these channels are supported only on x86 platforms using the gcc
compiler.  The necessary assembly instructions to guarantee proper ordering of
memory operations are lacking for other platforms and compilers.  That said, we
have seen a high success rate when testing these channels on unsupported
systems.

This patch release also includes a new unsupported channel.  The scalable
shared memory, or sshm, channel is similar to the shm channel except that it
allocates shared memory communication queues only when necessary instead of
preallocating N-squared queues.


===============================================================================
                               Changes in 0.96p1
===============================================================================

This patch release fixes a problem with building MPICH2 on Microsoft Windows
platforms.  It also corrects a serious bug in the poll implementation of the
Sock interface.


===============================================================================
                                Changes in 0.96
===============================================================================

The 0.96 distribution is largely a bug fix release.  In addition to the many
bug fixes, major improvements have been made to the code that supports the
dynamic process management routines (MPI_Comm_{connect,accept,spawn,...}()).
Additional changes are still required to support MPI_Comm_disconnect().

We also added an experimental (and thus completely unsupported) rdma device.
The internal interface is similar to the CH3 interface except that it contains
a couple of extra routines to inform the device about data transfers using the
rendezvous protocol.  The channel can use this extra information to pin memory
and perform a zero-copy transfer.  If all goes well, the results will be rolled
back into the CH3 device.

Due to last minute difficulties, this release does not contain the shm or ssm
channels.  These channels will be included in a subsequent patch release.


===============================================================================
                                Changes in 0.94
===============================================================================

Active target one-sided communication is now available for the ch3:sock
channel.  This new functionality has undergone some correctness testing but has
not been optimized in terms of performance.  Future release will include
performance enhancements, passive target communication, and availability in
channels other than just ch3:sock.

The shared memory channel (ch3:shm), which performs communication using shared
memory on a single machine, is now complete and has been extensively tested.
At present, this channel only supports IA32 based machines (excluding the
Pentium Pro which has a memory ordering bug).  In addition, this channel must
be compiled with gcc.  Future releases with support additional architectures
and compilers.

A new channel has been added that performs inter-node communication using
sockets (TCP/IP) and intra-node communication using shared memory.  This
channel, ch3:ssm, is ideal for clusters of SMPs.  Like the shared memory
channel (ch3:shm), this channel only supports IA32 based machines and must be
compiled with gcc.  In future releases, the ch3:ssm channel will support
additional architectures and compilers.

The two channels that perform commutation using shared memory, ch3:shm and
ch3:ssm, now support the allocation of shared memory using both the POSIX and
System V interfaces.  The POSIX interface will be used if available; otherwise,
the System V interface is used.

In the interest of increasing portability, many enhancements have been made to
both the code and the configure scripts.

And, as always, many bugs have been fixed :-).


***** INTERFACE CHANGES ****

The parameters to MPID_Abort() have changed.  MPID_Abort() now takes a pointer
to communicator object, an MPI error code, and an exit code.

MPIDI_CH3_Progress() has been split into two functions:
 MPIDI_CH3_Progress_wait() and MPIDI_CH3_Progress_test().


===============================================================================
                                Changes in 0.93
===============================================================================

Version 0.93 has undergone extensive changes to provide better error reporting.
Part of these changes involved modifications to the ADI3 and CH3 interfaces.
The following routines now return MPI error codes:

MPID_Cancel_send()
MPID_Cancel_recv()
MPID_Progress_poke()
MPID_Progress_test()
MPID_Progress_wait()
MPIDI_CH3_Cancel_send()
MPIDI_CH3_Progress()
MPIDI_CH3_Progress_poke()
MPIDI_CH3_iRead()
MPIDI_CH3_iSend()
MPIDI_CH3_iSendv()
MPIDI_CH3_iStartmsg()
MPIDI_CH3_iStartmsgv()
MPIDI_CH3_iWrite()
MPIDI_CH3U_Handle_recv_pkt()
MPIDI_CH3U_Handle_recv_req()
MPIDI_CH3U_Handle_send_req()

*******************************************************************************
Of special note are MPID_Progress_test(), MPID_Progress_wait() and
MPIDI_CH3_Progress() which previously returned an integer value indicating if
one or more requests had completed.  They no longer return this value and
instead return an MPI error code (also an integer).  The implication being that
while the semantics changed, the type signatures did not.
*******************************************************************************

The function used to create error codes, MPIR_Err_create_code(), has also
changed.  It now takes additional parameters, allowing it create a stack of
errors and making it possible for the reporting function to indicate in which
function and on which line the error occurred.  It also allows an error to be
designated as fatal or recoverable.  Fatal errors always result in program
termination regardless of the error handler installed by the application.

A RDMA channel has been added and includes communication methods for shared
memory and shmem.  This is recent development and the RDMA interface is still
in flux.