description: scheduler and memory

study/kernel/01-process/00-code/COW/COW.c

@@ -0,0 +1,37 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include <sys/types.h>
+#include <sys/mman.h>
+#include <unistd.h>
+
+#define MAP_SIZE 1024*1024
+
+int main(int argc, char **argv)
+{
+	unsigned char *m;
+	int i;
+	pid_t pid;
+
+	m = mmap(0, MAP_SIZE, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON, -1, 0);
+
+	for (i = 0; i < MAP_SIZE; i++)
+		m[i] = 10;
+
+	pid = fork();
+	if (pid == -1) {
+		exit(1);
+	} else if (pid == 0) {
+		sleep(10);
+	} else {
+		sleep (5);
+
+		/* Cow */
+		for (i = 0; i < MAP_SIZE; i++)
+			m[i] = 20;
+		printf("cow is done in parent pscess\n");
+		sleep(10);
+	}
+
+	return EXIT_SUCCESS;
+}

study/kernel/01-process/00-code/COW/Makefile

@@ -0,0 +1,18 @@
+target=fork COW
+
+
+
+all:$(target)
+
+fork : fork.o
+	$(CC) $^ -o $@ $(LDFLAGS)
+
+COW : COW.o
+	$(CC) $^ -o $@ $(LDFLAGS)
+
+%.o : %.c
+	$(CC) -g -c $^ -o $@  $(CFLAGS) $(DEFINES)
+
+clean :
+	rm -rf *.o
+	rm -rf $(target)

study/kernel/01-process/00-code/COW/fork.c

@@ -0,0 +1,26 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include <sys/types.h>
+#include <unistd.h>
+
+
+
+int data = 10;
+
+int main(int argc, char* argv[])
+{
+	int pid;
+
+	pid = fork();
+	if (pid == 0) {
+		printf("Child process %d, data %d\n", getpid(), data);
+		data = 20;
+		printf("Child process %d, data %d\n", getpid(), data);
+	} else {
+		sleep(1);
+		printf("Parent process %d, data %d\n", getpid(), data);
+	}
+
+	return EXIT_SUCCESS;
+}