feat(all2all)

all2all/main.cc

@@ -0,0 +1,74 @@
+#include <iostream>
+#include <mpi.h>
+
+#define BUFFER_SIZE 1
+
+void my_MPI_Alltoall(int *sendbuf, int *recvbuf, int count, MPI_Comm comm,
+                     int rank) {
+  // if (rank == 0) {
+  //  MPI_Recv(recvbuf + 1, 1, MPI_INT, 1, 1, MPI_COMM_WORLD,
+  //  MPI_STATUS_IGNORE); MPI_Send(sendbuf, 1, MPI_INT, 1, 0, MPI_COMM_WORLD);
+  //} else {
+  //  MPI_Send(sendbuf + 1, 1, MPI_INT, 0, 1, MPI_COMM_WORLD);
+  //  MPI_Recv(recvbuf, 1, MPI_INT, 0, 0, MPI_COMM_WORLD, MPI_STATUS_IGNORE);
+  //}
+  for (int i = 0; i < count; ++i) {
+    recvbuf[rank] = sendbuf[rank];
+    if (i == rank) {
+      // recv from other proc
+      for (int j = 0; j < count; ++j) {
+        if (j != rank) {
+          MPI_Recv(recvbuf + j, 1, MPI_INT, j, j, MPI_COMM_WORLD,
+                   MPI_STATUS_IGNORE);
+        }
+      }
+    } else {
+      // send to one proc
+      MPI_Send(sendbuf + i, 1, MPI_INT, i, rank, MPI_COMM_WORLD);
+    }
+  }
+}
+
+int main(int argc, char *argv[]) {
+  int rank, size;
+  int *send_buffer;
+  int *recv_buffer_test;
+  int *recv_buffer_val;
+  // MPI init
+  MPI_Init(&argc, &argv);
+  MPI_Comm_rank(MPI_COMM_WORLD, &rank);
+  MPI_Comm_size(MPI_COMM_WORLD, &size);
+  // end MPI init
+  send_buffer = new int[BUFFER_SIZE * size];
+  recv_buffer_test = new int[BUFFER_SIZE * size];
+  recv_buffer_val = new int[BUFFER_SIZE * size];
+
+  // init send_buffer
+  for (int i = 0; i < size; ++i) {
+    send_buffer[i] = rank + size * i;
+  }
+  // use my_MPI_Alltoall
+  my_MPI_Alltoall(send_buffer, recv_buffer_test, size, MPI_COMM_WORLD, rank);
+
+  // use MPI_Alltoall
+  MPI_Alltoall(send_buffer, BUFFER_SIZE, MPI_INT, recv_buffer_val, BUFFER_SIZE,
+               MPI_INT, MPI_COMM_WORLD);
+
+  // validate data
+  bool foundErr = false;
+  for (int i = 0; i < size; ++i) {
+    if (recv_buffer_test[i] != recv_buffer_val[i]) {
+      std::cout << "proc" << rank << ": "
+                << "test[" << i << "]:" << recv_buffer_test[i] << ", val[" << i
+                << "]:" << recv_buffer_val[i] << std::endl;
+      foundErr = true;
+    }
+  }
+  if (!foundErr) {
+    std::cout <<"proc" << rank << ": no err found" << std::endl;
+  }
+  delete[] send_buffer;
+  delete[] recv_buffer_val;
+  delete[] recv_buffer_test;
+  MPI_Finalize();
+}