add question code

exercises/MPI_examples/questions/Makefile

+OBJECTS = q1.o q2.o q3.o q4.o q5.o
+CC = mpicc
+CFLAGS = -Wall -std=c11
+CFLAGS += -I. # add the current directory to the include path
+PHONY_RUNS = run1 run2 run3 run4 run5
+PHONY_CLEANS = clean1 clean2 clean3 clean4 clean5
+
+.PHONY: all
+all: $(patsubst %.o,%,$(OBJECTS)) # build all binaries
+
+.PHONY: $(PHONY_RUNS)
+$(PHONY_RUNS): run%: q% # run a binary
+	time mpirun $<
+
+$(patsubst %.o,%,$(OBJECTS)): %: %.o # link the object files into a binary
+	$(CC) $(CFLAGS) $^ -o $@
+
+$(OBJECTS): %.o: %.c  # compile the source files into object files
+	$(CC) $(CFLAGS) -c $<
+
+.PHONY: clean
+clean: # remove the object files and the binary
+	rm -f $(OBJECTS) $(patsubst %.o,%,$(OBJECTS))
+
+.PHONY: $(PHONY_RUNS)
+$(PHONY_CLEANS): clean%: q% # run a binary
+	rm -f $<.o $<
+

exercises/MPI_examples/questions/README.md

+# Code from the questions
+
+This folder contains all the programs that are presented in the question PDF.
+
+## Build
+
+```c
+# build all programs
+make 
+
+# run specific program
+make run1
+make run2
+...
+make run5
+
+# clean specific build
+make clean1
+make clean2
+...
+make clean5
+
+# clean all builds
+make clean
+```

exercises/MPI_examples/questions/q1.c

+#include <mpi.h>
+#include <stdio.h>
+
+int main(int argc, char **argv) {
+
+  int sbuffer = 1;
+  int rbuffer = 2;
+  const int buflen = 1;
+  MPI_Init(&argc, &argv);
+
+  // Get the number of processes
+  int nprocs;
+  MPI_Comm_size(MPI_COMM_WORLD, &nprocs);
+
+  // Get the rank of the process
+  int procid;
+  MPI_Comm_rank(MPI_COMM_WORLD, &procid);
+
+  for (int p = 0; p < nprocs; p++) {
+    if (p != procid)
+      MPI_Send(&sbuffer, buflen, MPI_INT, p, 0, MPI_COMM_WORLD);
+    printf("Process %d blocking sent message to process %d\n", procid, p);
+  }
+
+  for (int p = 0; p < nprocs; p++) {
+    if (p != procid)
+      MPI_Recv(&rbuffer, buflen, MPI_INT, p, 0, MPI_COMM_WORLD,
+               MPI_STATUS_IGNORE);
+    printf("Process %d blocking received message from process %d\n", procid, p);
+  }
+  // Finalize the MPI environment. No more MPI calls can be made after this
+  MPI_Finalize();
+}

exercises/MPI_examples/questions/q2.c

+#include <mpi.h>
+#include <stdio.h>
+
+int main(int argc, char **argv) {
+
+  int sbuffer = 1;
+  int rbuffer = 2;
+  const int buflen = 1;
+  MPI_Init(&argc, &argv);
+
+  // Get the number of processes
+  int nprocs;
+  MPI_Comm_size(MPI_COMM_WORLD, &nprocs);
+
+  // Get the rank of the process
+  int procid;
+  MPI_Comm_rank(MPI_COMM_WORLD, &procid);
+
+  for (int p = 0; p < nprocs; p++) {
+    if (p != procid)
+      MPI_Recv(&rbuffer, buflen, MPI_INT, p, 0, MPI_COMM_WORLD, MPI_STATUS_IGNORE);
+    printf("Process %d blocking received message from process %d\n", procid, p);
+  }
+
+  for (int p = 0; p < nprocs; p++) {
+    if (p != procid)
+      MPI_Send(&sbuffer, buflen, MPI_INT, p, 0, MPI_COMM_WORLD);
+    printf("Process %d blocking sent message to process %d\n", procid, p);
+  }
+  // Finalize the MPI environment. No more MPI calls can be made after this
+  MPI_Finalize();
+}

exercises/MPI_examples/questions/q3.c

+#include <mpi.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+int main(int argc, char **argv) {
+
+  const int buflen = 1;
+  MPI_Init(&argc, &argv);
+
+  // Get the number of processes
+  int nprocs;
+  MPI_Comm_size(MPI_COMM_WORLD, &nprocs);
+
+  int *sbuffers = calloc(nprocs, sizeof(int));
+  int rbuffer = 0; 
+  MPI_Request *requests = (MPI_Request *) malloc(nprocs * sizeof(MPI_Request));
+
+  // Get the rank of the process
+  int procid;
+  MPI_Comm_rank(MPI_COMM_WORLD, &procid);
+
+  int ireq = 0;
+  for (int p = 0; p < nprocs; p++) {
+    if (p != procid)
+      MPI_Isend(&sbuffers[p], buflen, MPI_INT, p, 0, MPI_COMM_WORLD, &(requests[ireq++]));
+    printf("Process %d non-blocking sent message to process %d\n", procid, p);
+  }
+
+  for (int p = 0; p < nprocs; p++) {
+    if (p != procid)
+      MPI_Recv(&rbuffer, buflen, MPI_INT, p, 0, MPI_COMM_WORLD, MPI_STATUS_IGNORE);
+    printf("Process %d blocking received message from process %d\n", procid, p);
+  }
+  MPI_Waitall(nprocs-1, requests, MPI_STATUSES_IGNORE);
+  // Finalize the MPI environment. No more MPI calls can be made after this
+  MPI_Finalize();
+}

exercises/MPI_examples/questions/q4.c

+#include <mpi.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+int main(int argc, char **argv) {
+
+  const int buflen = 1;
+  MPI_Init(&argc, &argv);
+
+  // Get the number of processes
+  int nprocs;
+  MPI_Comm_size(MPI_COMM_WORLD, &nprocs);
+
+  int *rbuffers = calloc(nprocs, sizeof(int));
+  int sbuffer = 0; 
+  MPI_Request *requests = (MPI_Request *) malloc(nprocs * sizeof(MPI_Request));
+
+  // Get the rank of the process
+  int procid;
+  MPI_Comm_rank(MPI_COMM_WORLD, &procid);
+
+  int ireq = 0;
+  for (int p = 0; p < nprocs; p++) {
+    if (p != procid)
+      MPI_Irecv(&rbuffers[p], buflen, MPI_INT, p, 0, MPI_COMM_WORLD, &(requests[ireq++]));
+    printf("Process %d non-blocking received message from process %d\n", procid, p);
+  }
+
+  for (int p = 0; p < nprocs; p++) {
+    if (p != procid)
+      MPI_Send(&sbuffer, buflen, MPI_INT, p, 0, MPI_COMM_WORLD);
+    printf("Process %d blocking send message from process %d\n", procid, p);
+  }
+  MPI_Waitall(nprocs-1, requests, MPI_STATUSES_IGNORE);
+  // Finalize the MPI environment. No more MPI calls can be made after this
+  MPI_Finalize();
+}

exercises/MPI_examples/questions/q5.c

+#include <mpi.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+int main(int argc, char **argv) {
+
+  const int buflen = 1;
+  MPI_Init(&argc, &argv);
+
+  // Get the number of processes
+  int nprocs;
+  MPI_Comm_size(MPI_COMM_WORLD, &nprocs);
+
+  int *rbuffers = calloc(nprocs, sizeof(int));
+  int sbuffer = 0; 
+  MPI_Request *requests = (MPI_Request *) malloc(nprocs * sizeof(MPI_Request));
+
+  // Get the rank of the process
+  int procid;
+  MPI_Comm_rank(MPI_COMM_WORLD, &procid);
+
+  int ireq = 0;
+  for (int p = 0; p < nprocs; p++) {
+    if (p != procid)
+      MPI_Irecv(&rbuffers[p], buflen, MPI_INT, p, 0, MPI_COMM_WORLD, &(requests[ireq++]));
+    printf("Process %d non-blocking received message from process %d\n", procid, p);
+  }
+  MPI_Waitall(nprocs-1, requests, MPI_STATUSES_IGNORE);
+
+  for (int p = 0; p < nprocs; p++) {
+    if (p != procid)
+      MPI_Send(&sbuffer, buflen, MPI_INT, p, 0, MPI_COMM_WORLD);
+    printf("Process %d blocking send message from process %d\n", procid, p);
+  }
+  // Finalize the MPI environment. No more MPI calls can be made after this
+  MPI_Finalize();
+}