update slides, add waitall

exercises/MPI_examples/nb_waitall/Makefile

+PROG = nb_waitall
+OBJECTS = nb_waitall.o
+CC = mpicc
+CFLAGS = -Wall -std=c11
+CFLAGS += -I. # add the current directory to the include path
+
+$(PROG): $(OBJECTS) # link the object files into a binary
+	$(CC) $(CFLAGS) $^ -o $@
+
+.Phone: run
+run: $(PROG) # build and run the program
+	mpirun ./$(PROG);
+
+$(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) $(PROG)
+

exercises/MPI_examples/nb_waitall/nb_waitall.c

+#include <mpi.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+int main(int argc, char **argv) {
+
+  MPI_Init(&argc, &argv);
+
+  // Get the number of processes
+  int num_processes;
+  MPI_Comm_size(MPI_COMM_WORLD, &num_processes);
+
+  // Get the rank of the process
+  int rank;
+  MPI_Comm_rank(MPI_COMM_WORLD, &rank);
+
+  MPI_Request *requests =
+      (MPI_Request *) malloc(num_processes * sizeof(MPI_Request));
+  MPI_Status *statuses =
+      (MPI_Status *) malloc(num_processes * sizeof(MPI_Status));
+
+  char *recv_buffers = (char *)malloc(num_processes * sizeof(char));
+  char send_buffers = 'A';
+
+  send_buffers += rank;
+
+  MPI_Isend(&send_buffers, 1, MPI_CHAR, 0, 0,
+            MPI_COMM_WORLD, &requests[rank]);
+
+  // all processes send to rank 0
+  if (rank == 0) {
+    for (int i = 0; i < num_processes; i++)
+        MPI_Irecv(&recv_buffers[i], 1, MPI_CHAR, i, 0,
+                  MPI_COMM_WORLD, &requests[i]);
+    MPI_Waitall(num_processes, requests, statuses);
+    for (int i = 0; i < num_processes; i++) {
+      printf("Process 0 received token %c from process %d\n", recv_buffers[i],
+             statuses[i].MPI_SOURCE);
+    }
+  }
+
+  // Finalize the MPI environment. No more MPI calls can be made after this
+  MPI_Finalize();
+}

slides/pages/recap.md

@@ -600,3 +600,28 @@ If **MPI_Request** is Null, both **MPI_Wait** and **MPI_Test** returns immediate
 ### Demo
 
 See live demo.
+
+---
+title: Non-Blocking Request Testing 2
+---
+
+### Test and Wait on Many Requests
+
+**MPI_Waitany / MPI_Testany**:
+
+- Wait for one of the specified requests to complete and free it
+- Test if one of the specified requests has completed and free it if it did
+
+**MPI_Waitall / MPI_Testall**:
+
+- Wait for all the specified requests to complete and free them
+- Test if all of the specified requests have completed and free them if they have
+
+**MPI_Waitsome / MPI_Testsome**
+
+- Wait for any number of the specified requests to complete and free them
+- Test if any number of the specified requests have completed and free these that have
+
+Use **MPI_STATUSES_IGNORE** to ignore status from -all/-some operations.
+
+See live demo.