All functions require "eco.h" to be included.
[] is used to represent vectors. All functions are declared accepting void * for vector arguments.
TYPE is one of
For reduce and scan, OPERATION is one of
All functions (except barrier and bcast) have multivector forms. These are identical to the base operations except the function call ends in a v (e.g. eco_gather->eco_gatherv), the first argument is the (integer) number of vectors, and the send and receive vector arguments are now 2d.
root is the index of the root process in the tid array which is returned by eco_init (identical to the array that is passed unless a topology is requested). or, for some operations, it can be ECO_ALL, which is defined in eco.h
eco_gather (IN send_vector[], IN int send_length, IN int send_stride, IN int send_offset, OUT recv_vector[], IN int recv_length, IN int recv_stride, IN int root, IN TYPE) send_vector: vector with data to be gathered send_length: number of data elements in send_vector send_stride: stride for data in send_vector send_offset: position of send_vector in recv_vector recv_vector: resulting vector (root) recv_len: size of recv_vector (in terms of data elements) (root) recv_stride: stride of data in recv_vector (root) root: gathering process or ECO_ALL
gather takes all send vectors contributed by processes and combines them to form recv_vector, which is only used at root, unless root=ECO_ALL, in which case all processes receive the recv_vector. Overlapping send ranges will produce unpredictable results.
send_offset should specify the destination address with recv_stride already accounted for. Note that length parameters should not include stride
eco_scatter(IN send_vector[], IN int send_length, IN int send_stride, IN int lengths[], IN int offsets[], OUT recv_vector[], IN int recv_length, IN int recv_stride, IN int root, IN TYPE) send_vector: data to be scattered (root) send_length: number of data items (root) send_stride: stride of data in send_vector (root) lengths: number of items process i should receive (root) offsets: offset of data process i should receive (root) recv_vector: part of data for process recv_length: length of data for process recv_stride: stride of data in recv_vector root: scattering process
scatter divides data input on root and distributes one chunk to each process (including the root process). It does check that output_vector is large enough to store what is passed to it, although overlaps within send_vector are not checked for.
Note that offsets should specify the source address with stride already accounted for. length parameters should not include stride
eco_alltoall(IN send_vector[], IN int send_length, IN int send_stride, IN int send_lengths[], IN int send_offsets[], OUT recv_vector[], IN int recv_length, IN int recv_stride, IN int recv_lengths[], IN int recv_offsets[], TYPE) send_vector: data to be scattered send_length: number of data items in send_vector of send_vector send_lengths: number of items process i should receive send_offsets: offset of data process i should receive recv_vector: data to be gathered recv_length: number of data items to be gathered recv_lengths: number of items to be received from process i recv_offsets: offset in recv_vector at which to store data from process i
alltoall is essentially a combined scatter/gather where each process sends distinct data to each other process.
Note that offsets should specify the source address with stride already accounted for. length parameters should not include stride
eco_reduce(IN send_vector[], IN int length, IN int stride, OUT recv_vector[], IN OP_TYPE operation, IN int root, TYPE) send_vector: local contribution of data length: number of data items in send_vector and recv_vector stride: stride of send_vector and recv_vector recv_vector: result (root) operation: operation type root: receiving process or ECO_ALL
reduce does operation across all copies of send_vector. This operation is elementwise, so recv_vector[i] = OPERATION across all send_vector[i].
the length parameter should not reflect stride
eco_scan(IN send_vector[], IN int length, IN int stride
OUT recv_vector[], IN OP_TYPE operation, TYPE)
send_vector: local contribution of data
length: number of data items in send_vector and recv_vector
stride: stride of send_vector and recv_vector
recv_vector: operation performed on first 0..i contributions
operation: operation to do on send_vector
scan implements an inclusive scan, such that the vector returned to process i is the result of applying operation to send_vector from processes 0..i.
eco_barrier()
waits until all processes reach call before completing
eco_bcast(IN int root)
Broadcasts the current send buffer from the root node to all nodes (including root). All processes must call this or other processes may not receive the message. Message is received into a new receive buffer, as with pvm_recv.
eco_init (IN/OUT int* p_i, IN int p, IN/OUT int tids[], char data_filename[], IN int topology) p_i: pvm_mytid() = tids[p_i] 0<=p_i<p p: number of tasks participating in collective communication tids: array of tids. returned in new order if topology is used data_filename: network database filename (used by p_i=0) defaults to a compile time value if NULL topology: topology to provide for local communication. values: ECO_DEFAULT_TOPOLOGY ECO_RING_TOPOLOGY
eco_init is used to read in the database and generate patterns for collective communication. It must be called by all tasks. If topology is set to something other than ECO_DEFAULT_TOPOLOGY (0), tids may be returned in a different order.
eco_register_function(function)
registers function as a binary operation for reduce and scan. returns the (integer) identifier to be passed to reduce and scan
The function should be of type
void ECO_user_function(void* In, void* InOut, int length, int* info);
and should implement the operation
for(i=0;i<length;i++) InOut[i] = InOut[i] (+) In[i];
info is reserved for returning status, although it is currently not used. (+) must be both associative and commutative
eco_delete_function(int function_id)
deletes the function previously registered