おはようゴーストゾーンを作成する適切な方法MPI [halos]
私は並列プログラミングコースに参加しています。教師は、ステンシル計算のためのドメインパーティションを含む割り当てを私たちに与えました。このタイプの計算(有限差分)の場合、コードを並列化する最も一般的な方法は、ドメインを分割していくつかのゴーストゾーン(ハロー)を作成することです。
私はこの簡単な例をプログラムして、内側の値= 123と境界値88を持ついくつかの配列を初期化しました。すべての通信の最後に、すべてのゴースト値は8のままでなければなりません。私は123の値を得ています。
(なし幽霊)シリアル:
123 - 123 - ... - 123 - 123
2つのパーティション:
123 - 123 - ... - 88 ||| 88 - ... - 123 - 123
3つのパーティション:
123 - 123 - ... - 88 ||| 88 - ... - 123 - 123 - 88 ||| 88 - ... - 123 - 123
さておき、このバグから、ここでの主な問題は、正しいについてですゴーストゾーンを作成し維持するためのアプローチ。私の厄介な場合(MYID == ....それ以外の場合(MYID = ...人々は通常、並列処理のこの種を実装する方法を実装?の他のタイプ?
#include<mpi.h>
#include<stdio.h>
#include<stdlib.h>
int WhichSize(int mpiId, int numProc, int tam);
int main(int argc, char *argv[]){
int i;
int localSize;
int numProc;
int myid;
int leftProc;
int rightProc;
int * myArray;
int fullDomainSize = 16;
MPI_Request request;
MPI_Init(&argc, &argv);
MPI_Comm_size(MPI_COMM_WORLD, &numProc);
MPI_Comm_rank(MPI_COMM_WORLD, &myid);
// Lets get each partition size.
localSize = WhichSize(myid, numProc, fullDomainSize);
// Allocate arrays acording to proc number.
if(numProc == 1){
//printf("Allocating Array for serial usage\n");
myArray = (int*)malloc(localSize*sizeof(int));
} else if(numProc == 2) {
//printf("Allocating Array for 2 proc usage\n");
myArray = (int*)malloc((localSize+ 1)*sizeof(int));
} else if(numProc > 2) {
if (myid == 0 || myid == numProc - 1){
//printf("Allocating array for boundary nodes usage\n");
myArray = (int*)malloc((localSize+ 1)*sizeof(int));
} else {
//printf("Allocating array for inner nodes usage\n");
myArray = (int*)malloc((localSize+ 2)*sizeof(int));
}
}
// Now we will fill the arrays with a dummy value 123. For the
// boundaries (ghosts) we will fill than with 80. Just to differe
// ntiate.
if(numProc == 1){
//printf("----------------------------------------\n");
//printf("Filling the serial array with values... \n");
for (i = 0; i<localSize; i++){
myArray[i] = 123;
}
} else if(numProc == 2) {
////printf("------------------------------------------------\n");
//printf("Filling array for two proc usage with values... \n");
for (i = 0; i<localSize; i++){
myArray[i] = 123;
}
// ghost.
myArray[localSize+1] = 8;
} else if(numProc > 2) {
if (myid == 0 || myid == numProc - 1){
//printf("--------------------------------------------------\n");
//printf("Filling boundary node arrays usage with values... \n");
for (i = 0; i<localSize; i++){
myArray[i] = 123;
}
// ghosts.
myArray[localSize+1] = 8;
} else {
//printf("--------------------------------------------------\n");
//printf("Filling inner node arrays usage with values... \n");
for (i = 0; i<localSize; i++){
myArray[i] = 123;
}
// ghosts.
myArray[localSize+1] = 8;
myArray[0] = 8;
}
}
// Now lets comunicate the ghosts with MPI_Sendrecv().
if(numProc == 1){
//printf("Serial usage, no ghost to comunicate \n");
} else if(numProc == 2) {
if (myid == 0){
//printf("Sending ghost value from proc %d to %d\n", myid, myid + 1);
MPI_Isend(&myArray[localSize+1],
1,
MPI_INT,
1,
12345,
MPI_COMM_WORLD,
&request);
} else if (myid == 1) {
//printf("Receiving ghost value from proc %d to %d\n", myid-1, myid);
MPI_Irecv(&myArray[localSize+1],
1,
MPI_INT,
0,
12345,
MPI_COMM_WORLD,
&request);
}
} else if(numProc > 2) {
if (myid == 0){
rightProc = myid + 1;
if (myid == 0){
//printf("-------------------------------\n");
//printf("Communicating Boundary ghosts !\n");
//printf("-------------------------------\n");
//printf("Sending ghost value from proc %d to %d\n", myid, myid + 1);
MPI_Isend(&myArray[localSize+1],
1,
MPI_INT,
rightProc,
12345,
MPI_COMM_WORLD,
&request);
} else if (myid == rightProc) {
//printf("Receiving ghost value from proc %d to %d\n", myid-1, myid);
MPI_Irecv(&myArray[localSize+1],
1,
MPI_INT,
0,
12345,
MPI_COMM_WORLD,
&request);
}
} else if (myid == numProc - 1) {
leftProc = myid - 1;
if (myid == numProc - 1){
//printf("-------------------------------\n");
//printf("Communicating Boundary ghosts !\n");
//printf("-------------------------------\n");
////printf("Sending ghost value from proc %d to %d\n", myid, myid + 1);
MPI_Isend(&myArray[localSize+1],
1,
MPI_INT,
leftProc,
12345,
MPI_COMM_WORLD,
&request);
} else if (myid == leftProc) {
rightProc = myid + 1;
//printf("Receiving ghost value from proc %d to %d\n", myid-1, myid);
MPI_Irecv(&myArray[localSize+1],
1,
MPI_INT,
rightProc,
12345,
MPI_COMM_WORLD,
&request);
}
} else {
//printf("-------------------------------\n");
//printf("Communicating Inner ghosts baby\n");
//printf("-------------------------------\n");
leftProc = myid - 1;
rightProc = myid + 1;
// Communicate tail ghost.
if (myid == leftProc) {
MPI_Isend(&myArray[localSize+1],
1,
MPI_INT,
rightProc,
12345,
MPI_COMM_WORLD,
&request);
} else if (myid == rightProc){
MPI_Irecv(&myArray[localSize+1],
1,
MPI_INT,
leftProc,
12345,
MPI_COMM_WORLD,
&request);
}
// Communicate head ghost.
if (myid == leftProc) {
MPI_Isend(&myArray[0],
1,
MPI_INT,
rightProc,
12345,
MPI_COMM_WORLD,
&request);
} else if (myid == rightProc){
MPI_Irecv(&myArray[0],
1,
MPI_INT,
leftProc,
12345,
MPI_COMM_WORLD,
&request);
}
}
}
// Now I Want to see if the ghosts are in place !.
if (myid == 0){
printf("The ghost value is: %d\n", myArray[localSize + 1]);
} else if (myid == numProc - 1){
printf("The ghost value is: %d\n", myArray[0]);
} else {
printf("The head ghost is: %d\n", myArray[0]);
printf("The tail ghost is: %d\n", myArray[localSize + 1]);
}
MPI_Finalize();
exit(0);
}
int WhichSize(int mpiId, int numProc, int tam){
double resto;
int tamLocal;
tamLocal = tam/numProc;
resto = tam - tamLocal*numProc;
if (mpiId < resto) tamLocal = tamLocal + 1;
return tamLocal;
}
感謝別に、このためのクリーナー解決策はあります皆さん!
は、ご返信いただきありがとうございます! –