ex2: make parallel job init

exercise2/Makefile

@@ -2,9 +2,11 @@ CC      := gcc
 CFLAGS  := -Wall -Wextra -std=c17
 SRC     := mandel_mpi.c
 TARGET  := $(SRC:.c=)
-ARGS    := 1
 OUTDIR  := out
+OUT     := $(OUTDIR)/$(TARGET)
+ARGS    := 1
 NBENCH  := 1
+NPROC   := 3
 
 .PHONY: all clean run
 
@@ -12,7 +14,7 @@ all: clean run
 
 $(TARGET): $(SRC)
 	mkdir -p $(OUTDIR)
-	$(CC) $(CFLAGS) -o $(OUTDIR)/$@ $<
+	$(CC) $(CFLAGS) -o $(OUT) $<
 
 run: $(TARGET)
 	cd $(OUTDIR) && ./$< $(ARGS)
@@ -21,4 +23,8 @@ clean:
 	rm -rf $(OUTDIR)
 
 time: $(TARGET)
-	python3 bench.py '$(OUTDIR)/$(TARGET) 0' $(NBENCH)
+	python3 bench.py './$(OUT) 0' $(NBENCH)
+
+parallel: $(SRC)
+	mpicc -o $(OUT) $(SRC)
+	mpirun -np $(NPROC) $(OUT)

exercise2/mandel_mpi.c

@@ -1,4 +1,5 @@
 #include <math.h>
+#include <mpi.h>
 #include <stdio.h>
 #include <stdlib.h>
 
@@ -81,6 +82,11 @@ void fancycolour(uchar *p, int iter) {
 }
 
 int main(int argc, char **argv) {
+  MPI_Init(&argc, &argv);
+  int rank, size;
+  MPI_Comm_rank(MPI_COMM_WORLD, &rank);
+  MPI_Comm_size(MPI_COMM_WORLD, &size);
+  printf("hello from rank %d/%d", rank, size);
   if (argc == 1) {
     puts("Usage: MANDEL n");
     puts("n decides whether image should be written to disk (1=yes, 0=no)");
@@ -107,5 +113,6 @@ int main(int argc, char **argv) {
     /* write image to disk */
     savebmp("mandel.bmp", buffer, XSIZE, YSIZE);
   }
+  MPI_Finalize();
   return 0;
 }