. , -- . , .
, , . , , . 1, s , . :T1 = TS + .
, N V , / N, :T2=TS+ Tp/N.
, , , , := }/2 = (Ts + Tp) / (Ts + Tp/N) = 1/(S + P/N),
S= Ts / (Ts + Tp) P= Tp / (Ts + Tp) (S+ = 1). ( ) . 2.5. .
, () - . , . , .
2. /. MPI_Bsend(), MPI_Brecv.
. - : . MPI , . . .
, .. , .
B (buffered) - . , . , . .
MPI_Bsend . -, , . . , , . .
int MPI_Bsend(void *buf, int count, MPI_Datatype datatype,int dest, int tag, MPI_Comm comm)
buf- ; count ; datatype ; dest - , comm; tag ( nread nwrite PSE nCUBE2); comm .
MPI_Bsend(&buffer, buffsize, MPI_INT, 1, TAG, MPI_COMM_WORLD);