2. Section Message Data
on page Message Data
,
Section C++ Datatypes
on page C++ Datatypes
, and
Annex Defined Values and Handles
on page Defined Values and Handles
.
MPI_LONG_LONG_INT, MPI_LONG_LONG (as synonym), MPI_UNSIGNED_LONG_LONG,
MPI_SIGNED_CHAR,
and MPI_WCHAR are moved from optional to official and they are therefore
defined for all three language bindings.
3. Section Return Status
on page Return Status
.
MPI_GET_COUNT with zero-length datatypes:
The value returned as the count argument of
MPI_GET_COUNT for a datatype of length zero where zero bytes
have been transferred is zero. If the number of bytes transferred is
greater than zero, MPI_UNDEFINED is returned.
4. Section Derived Datatypes
on page Derived Datatypes
.
General rule about derived datatypes:
Most datatype constructors have replication count or block length arguments.
Allowed values are nonnegative integers. If the value is zero, no elements are
generated in the type map and there is no effect on datatype bounds or
extent.
5. Section Canonical MPI_PACK and MPI_UNPACK
on page Canonical MPI_PACK and MPI_UNPACK
.
MPI_BYTE should be used to send and receive data that is packed
using MPI_PACK_EXTERNAL.
6. Section All-Reduce
on page All-Reduce
.
If comm is an intercommunicator in MPI_ALLREDUCE, then
both groups should
provide count and datatype arguments that specify the same type
signature
(i.e., it is not necessary that both groups provide the same count value).
7. Section Group Accessors
on page Group Accessors
.
MPI_GROUP_TRANSLATE_RANKS and MPI_PROC_NULL:
MPI_PROC_NULL is a valid rank for input to
MPI_GROUP_TRANSLATE_RANKS, which returns
MPI_PROC_NULL as the translated rank.
8. Section Caching
on page Caching
.
About the attribute caching functions:
Advice
to implementors.
High-quality implementations should raise an error when a keyval
that was created by a call to MPI_XXX_CREATE_KEYVAL is
used with an object of the wrong type with a call to
MPI_YYY_GET_ATTR, MPI_YYY_SET_ATTR, MPI_YYY_DELETE_ATTR, or
MPI_YYY_FREE_KEYVAL. To do so, it is necessary to maintain, with
each keyval, information on the type of the associated user
function.
( End of advice to implementors.)
9. Section Naming Objects
on page Naming Objects
.
In MPI_COMM_GET_NAME:
In C, a null character is additionally stored at name[resultlen].
resultlen cannot be larger then MPI_MAX_OBJECT-1.
In Fortran, name is padded on the right with blank characters.
resultlen cannot be larger then MPI_MAX_OBJECT.
10. Section Overview of the Functions
on page Overview of the Functions
.
About MPI_GRAPH_CREATE and MPI_CART_CREATE:
All input arguments must have identical values on all processes
of the group of comm_old.
11. Section Cartesian Constructor
on page Cartesian Constructor
.
In MPI_CART_CREATE:
If ndims is zero then a zero-dimensional Cartesian topology is created. The
call is erroneous if it specifies a grid that is larger than the group size or if
ndims is negative.
12. Section General (Graph) Constructor
on page General (Graph) Constructor
.
In MPI_GRAPH_CREATE:
If the graph is empty, i.e., nnodes == 0,
then MPI_COMM_NULL is returned in all processes.
13. Section General (Graph) Constructor
on page General (Graph) Constructor
.
In MPI_GRAPH_CREATE:
A single process is allowed to be defined multiple times in the list of
neighbors of a process (i.e., there may be multiple edges between two
processes). A process is also allowed to be a neighbor to itself (i.e., a self
loop in the graph). The adjacency matrix is allowed to be non-symmetric.
Advice to users.
Performance implications of using multiple edges or a non-symmetric
adjacency matrix are not defined. The definition of a node-neighbor
edge does not imply a direction of the communication.
( End of advice to users.)
14. Section Topology Inquiry Functions
on page Topology Inquiry Functions
.
In MPI_CARTDIM_GET and MPI_CART_GET:
If comm is associated with a zero-dimensional Cartesian topology,
MPI_CARTDIM_GET returns ndims=0 and MPI_CART_GET will keep
all output arguments unchanged.
15. Section Topology Inquiry Functions
on page Topology Inquiry Functions
.
In MPI_CART_RANK:
If comm is associated with a zero-dimensional Cartesian topology,
coord is not significant and 0 is returned in rank.
16. Section Topology Inquiry Functions
on page Topology Inquiry Functions
.
In MPI_CART_COORDS:
If comm is associated with a zero-dimensional Cartesian topology,
coords will be unchanged.
17. Section Cartesian Shift Coordinates
on page Cartesian Shift Coordinates
.
In MPI_CART_SHIFT:
It is erroneous to call MPI_CART_SHIFT with a direction that is either
negative or greater than or equal to the number of dimensions in the Cartesian
communicator. This implies that it is erroneous to call MPI_CART_SHIFT with a
comm that is associated with a zero-dimensional Cartesian topology.
18. Section Partitioning of Cartesian structures
on page Partitioning of Cartesian structures
.
In MPI_CART_SUB:
If all entries in remain_dims are false or comm is already associated
with a zero-dimensional Cartesian topology then newcomm is associated
with a zero-dimensional Cartesian topology.
19. Section Environmental Inquiries
on page Environmental Inquiries
.
In MPI_GET_PROCESSOR_NAME:
In C, a null character is additionally stored at name[resultlen].
resultlen cannot be larger then MPI_MAX_PROCESSOR_NAME-1.
In Fortran, name is padded on the right with blank characters.
resultlen cannot be larger then MPI_MAX_PROCESSOR_NAME.
20. Section Error Handling
on page Error Handling
.
MPI_{COMM,WIN,FILE}_GET_ERRHANDLER behave as if a
new error handler object is created.
That is, once the error handler is no longer needed,
MPI_ERRHANDLER_FREE should be called with the error handler returned
from MPI_ERRHANDLER_GET or
MPI_{COMM,WIN,FILE}_GET_ERRHANDLER
to mark the error handler for deallocation.
This provides behavior similar to that of MPI_COMM_GROUP and
MPI_GROUP_FREE.
21. Section Startup
on page Startup
, see explanations to MPI_FINALIZE.
MPI_FINALIZE is collective over all connected processes.
If no processes were spawned, accepted or connected then this means
over MPI_COMM_WORLD; otherwise it is collective over the
union of all processes that have been and continue to be connected,
as explained in Section Releasing Connections
on page Releasing Connections
.
22. Section Startup
on page Startup
.
About MPI_ABORT:
Advice to users.
Whether the errorcode is returned from the executable or
from the MPI process startup mechanism (e.g., mpiexec), is an aspect of
quality of the MPI library but not mandatory.
( End of advice to users.)
Advice
to implementors.
Where possible, a high-quality implementation will
try to return the errorcode from the MPI process startup mechanism (e.g.
mpiexec or singleton init).
( End of advice to implementors.)
23. Section The Info Object
on page The Info Object
.
An implementation must support info objects as caches for arbitrary ( key,
value) pairs, regardless of whether it recognizes the key. Each function that
takes hints in the form of an MPI_Info must be prepared to ignore any key it
does not recognize. This description of info objects does not attempt to
define how a particular function should react if it recognizes a key but not the
associated value.
MPI_INFO_GET_NKEYS, MPI_INFO_GET_NTHKEY,
MPI_INFO_GET_VALUELEN, and MPI_INFO_GET
must retain all ( key, value)
pairs so that layered functionality can also use the Info object.
24.
Section Communication Calls
on page Communication Calls
.
MPI_PROC_NULL is a valid target rank in the MPI RMA calls
MPI_ACCUMULATE, MPI_GET, and MPI_PUT.
The effect is the same as for MPI_PROC_NULL in MPI point-to-point
communication.
See also item Changes from Version 2.0 to Version 2.1
in this list.
25.
Section Communication Calls
on page Communication Calls
.
After any RMA operation with rank MPI_PROC_NULL, it is still necessary to
finish the RMA epoch with the synchronization method that started the epoch.
See also item Changes from Version 2.0 to Version 2.1
in this list.
26. Section Accumulate Functions
on page Accumulate Functions
.
MPI_REPLACE
in MPI_ACCUMULATE,
like the other predefined operations,
is defined only for the predefined MPI datatypes.
27. Section File Info
on page File Info
.
About MPI_FILE_SET_VIEW and MPI_FILE_SET_INFO:
When an info object that specifies a subset of valid hints is passed to
MPI_FILE_SET_VIEW or MPI_FILE_SET_INFO,
there will be no effect on
previously set or defaulted hints that the info does not specify.
28. Section File Info
on page File Info
.
About MPI_FILE_GET_INFO:
If no hint exists
for the file associated with fh,
a handle to a newly created info object is returned that
contains no key/value pair.
29. Section File Views
on page File Views
.
If a file does not have the mode MPI_MODE_SEQUENTIAL,
then MPI_DISPLACEMENT_CURRENT is invalid as disp in
MPI_FILE_SET_VIEW.
30. Section External Data Representation: ``external32''
on page External Data Representation: ``external32''
.
The bias of 16 byte doubles was defined with 10383. The correct value is 16383.
31. Section Class Member Functions for MPI
on page Class Member Functions for MPI
.
In the example in this section,
the buffer should be declared as const void* buf.
32. Section Additional Support for Fortran Numeric Intrinsic Types
on page Additional Support for Fortran Numeric Intrinsic Types
.
About MPI_TYPE_CREATE_F90_xxxx:
Advice
to implementors.
An application may often repeat a call to
MPI_TYPE_CREATE_F90_xxxx with the same combination of
( xxxx, p, r).
The application is not allowed to free the returned predefined, unnamed
datatype handles. To prevent the creation of a potentially huge amount of
handles, the MPI implementation should return the same datatype handle for
the same ( REAL/COMPLEX/INTEGER, p, r) combination.
Checking for the
combination ( p, r) in the preceding call to
MPI_TYPE_CREATE_F90_xxxx and
using a hash-table to find formerly generated handles should limit the
overhead of finding a previously generated datatype with same combination
of ( xxxx, p, r).
( End of advice to implementors.)
33. Section Defined Constants
on page Defined Constants
.
MPI_BOTTOM is defined as
void * const MPI::BOTTOM.