.

Sheet7/Ex_1234/first_template/Makefile

@@ -0,0 +1,23 @@
+#
+#  Compile with
+#   make 2>&1 | grep -v openmpi
+#  to avoid warnings caused by OpenMPI
+
+# use GNU-Compiler tools
+COMPILER=GCC_
+# alternatively from the shell
+# export COMPILER=GCC_
+# or, alternatively from the shell
+# make COMPILER=GCC_
+
+MAIN = main
+SOURCES = ${MAIN}.cpp greetings.cpp
+OBJECTS = $(SOURCES:.cpp=.o)
+
+PROGRAM	= ${MAIN}.${COMPILER}
+
+# uncomment the next to lines for debugging and detailed performance analysis
+CXXFLAGS += -g
+LINKFLAGS +=
+
+include ../${COMPILER}default.mk

Sheet7/Ex_1234/first_template/greetings.cpp

@@ -0,0 +1,86 @@
+#include "greetings.h"
+#include <cassert>
+#include <cstring>
+#include <iostream>
+#include <mpi.h>                                  // MPI
+#include <string>
+using namespace std;
+
+// see  http://www.open-mpi.org/doc/current
+// for details on MPI functions
+
+void greetings(MPI_Comm const &icomm)
+{
+    int myrank, numprocs;
+    MPI_Comm_rank(icomm, &myrank);                // my MPI-rank
+    MPI_Comm_size(icomm, &numprocs);              // #MPI processes
+    char *name  = new char [MPI_MAX_PROCESSOR_NAME],
+         *chbuf = new char [MPI_MAX_PROCESSOR_NAME];
+
+    int reslen, ierr;
+    MPI_Get_processor_name( name, &reslen);
+
+    if (0==myrank) {
+        cout << "   " << myrank << " runs on " << name << endl;
+
+        for (int i = 1; i < numprocs; ++i) {
+            MPI_Status stat;
+            stat.MPI_ERROR = 0;            // M U S T   be initialized!!
+
+            ierr = MPI_Recv(chbuf, MPI_MAX_PROCESSOR_NAME, MPI_CHAR, i, MPI_ANY_TAG, icomm, &stat);
+            assert(0==ierr);
+
+            cout << "   " << stat.MPI_SOURCE << " runs on " << chbuf;
+            int count;
+            MPI_Get_count(&stat, MPI_CHAR, &count); // size of received data
+            cout << " (length: " << count << " )" << endl;
+            //  stat.Get_error()	// Error code
+        }
+    }
+    else {
+        int dest = 0;
+        ierr = MPI_Send(name, strlen(name) + 1, MPI_CHAR, dest, myrank, icomm);
+        assert(0==ierr);
+    }
+    delete [] chbuf;
+    delete [] name;
+    return;
+}
+
+
+void greetings_cpp(MPI_Comm const &icomm)
+{
+    int myrank, numprocs;
+    MPI_Comm_rank(icomm, &myrank);                // my MPI-rank
+    MPI_Comm_size(icomm, &numprocs);              // #MPI processes
+    string name(MPI_MAX_PROCESSOR_NAME,'#'),      // C++
+           recvbuf(MPI_MAX_PROCESSOR_NAME,'#');   // C++: receive buffer, don't change size
+
+    int reslen, ierr;
+    MPI_Get_processor_name(name.data(), &reslen);
+    name.resize(reslen);                          // C++
+
+    if (0==myrank) {
+        cout << "   " << myrank << " runs on " << name << endl;
+        for (int i = 1; i < numprocs; ++i) {
+            MPI_Status stat;
+            stat.MPI_ERROR = 0;            // M U S T   be initialized!!
+
+            ierr = MPI_Recv(recvbuf.data(), MPI_MAX_PROCESSOR_NAME, MPI_CHAR, i, MPI_ANY_TAG, icomm, &stat);
+            assert(0==ierr);
+
+            int count;
+            MPI_Get_count(&stat, MPI_CHAR, &count); // size of received data
+            string const chbuf(recvbuf,0,count);    // C++
+            cout << "   " << stat.MPI_SOURCE << " runs on " << chbuf;
+            cout << " (length: " << count << " )" << endl;
+            //  stat.Get_error()	// Error code
+        }
+    }
+    else {
+        int dest = 0;
+        ierr = MPI_Send(name.data(), name.size(), MPI_CHAR, dest, myrank, icomm);
+        assert(0==ierr);
+    }
+    return;
+}

Sheet7/Ex_1234/first_template/greetings.h

@@ -0,0 +1,16 @@
+//	general header for all functions in directory
+
+#ifndef GREETINGS_FILE
+#define GREETINGS_FILE
+
+#include <mpi.h>
+
+/**	Each process finds out its host, sends this information
+	to root process 0 which prints this information for each process.
+	@param[in]	icomm	the MPI process group that is used.
+*/
+
+void greetings(MPI_Comm const &icomm);
+void greetings_cpp(MPI_Comm const &icomm);
+
+#endif

Sheet7/Ex_1234/first_template/main.cpp

@@ -0,0 +1,34 @@
+//		MPI code in C++.
+//		See [Gropp/Lusk/Skjellum, "Using MPI", p.33/41 etc.]
+//		and  /opt/mpich/include/mpi2c++/comm.h  for details
+
+#include "greetings.h"
+#include <iostream>                               // MPI
+#include <mpi.h>
+using namespace std;
+
+int main(int argc, char *argv[])
+{
+    MPI_Comm icomm = MPI_COMM_WORLD;
+    
+    MPI_Init(&argc, &argv);
+    int myrank, numprocs;
+    // numprocs = 1;    // delete this line when uncommenting the next line
+    MPI_Comm_rank(icomm, &myrank);                          // my MPI-rank
+    MPI_Comm_size(icomm, &numprocs);
+
+    if (0==myrank) {
+        cout << "\n There are " << numprocs << " processes running.\n \n";
+    }
+
+    greetings(icomm);
+    greetings_cpp(icomm); 
+
+    if (0==myrank) cout << endl;
+
+    MPI_Finalize();
+
+    return 0;
+}
+
+