diff --git a/Makefile b/Makefile
index fe25dc4..8012888 100644
--- a/Makefile
+++ b/Makefile
@@ -170,6 +170,8 @@ UPROGS=\
 	_usertests\
 	_wc\
 	_zombie\
+	_bigtest\
+	#_getcount\
 
 fs.img: mkfs README $(UPROGS)
 	./mkfs fs.img README $(UPROGS)
@@ -206,9 +208,9 @@ QEMUGDB = $(shell if $(QEMU) -help | grep -q '^-gdb'; \
 	then echo "-gdb tcp::$(GDBPORT)"; \
 	else echo "-s -p $(GDBPORT)"; fi)
 ifndef CPUS
-CPUS := 2
+CPUS := 1
 endif
-QEMUOPTS = -hdb fs.img xv6.img -smp $(CPUS) -m 512 $(QEMUEXTRA)
+QEMUOPTS = -hdb fs.img xv6.img -smp $(CPUS) -m 512 $(QEMUEXTRA) -snapshot
 
 qemu: fs.img xv6.img
 	$(QEMU) -serial mon:stdio $(QEMUOPTS)
diff --git a/bigtest.c b/bigtest.c
new file mode 100644
index 0000000..6ed76fe
--- /dev/null
+++ b/bigtest.c
@@ -0,0 +1,51 @@
+#include "types.h"
+#include "stat.h"
+#include "user.h"
+#include "fcntl.h"
+
+int
+main()
+{
+  char buf[512];
+  int fd, i, sectors;
+
+  fd = open("big.file", O_CREATE | O_WRONLY);
+  if(fd < 0){
+    printf(2, "big: cannot open big.file for writing\n");
+    exit();
+  }
+
+  sectors = 0;
+  while(1){
+    *(int*)buf = sectors;
+    int cc = write(fd, buf, sizeof(buf));
+    if(cc <= 0)
+      break;
+    sectors++;
+	if (sectors % 100 == 0)
+		printf(2, ".");
+  }
+
+  printf(1, "\nwrote %d sectors\n", sectors);
+
+  close(fd);
+  fd = open("big.file", O_RDONLY);
+  if(fd < 0){
+    printf(2, "big: cannot re-open big.file for reading\n");
+    exit();
+  }
+  for(i = 0; i < sectors; i++){
+    int cc = read(fd, buf, sizeof(buf));
+    if(cc <= 0){
+      printf(2, "big: read error at sector %d\n", i);
+      exit();
+    }
+    if(*(int*)buf != i){
+      printf(2, "big: read the wrong data (%d) for sector %d\n",
+             *(int*)buf, i);
+      exit();
+    }
+  }
+
+  exit();
+}
diff --git a/getcount.c b/getcount.c
new file mode 100644
index 0000000..1ecb5f4
--- /dev/null
+++ b/getcount.c
@@ -0,0 +1,19 @@
+#include "types.h"
+#include "user.h"
+#include "syscall.h"
+
+int
+main(int argc, char *argv[])
+{
+  printf(1, "initial fork count %d\n", getcount(SYS_fork));
+  if (fork() == 0) {
+    printf(1, "child fork count %d\n", getcount(SYS_fork));
+    printf(1, "child write count %d\n", getcount(SYS_write));
+  } else {
+    wait();
+    printf(1, "parent fork count %d\n", getcount(SYS_fork));
+    printf(1, "parent write count %d\n", getcount(SYS_write));
+  }
+  printf(1, "wait count %d\n", getcount(SYS_wait));
+  exit();
+}
diff --git a/mkfs.c b/mkfs.c
index 4b0e329..940105e 100644
--- a/mkfs.c
+++ b/mkfs.c
@@ -13,10 +13,10 @@
 
 #define static_assert(a, b) do { switch (0) case 0: case (a): ; } while (0)
 
-int nblocks = 985;
+int nblocks = 25000;
 int nlog = LOGSIZE;
 int ninodes = 200;
-int size = 1024;
+int size = 25045;
 
 int fsfd;
 struct superblock sb;