copy-on-write and copy-on-demand

passes forktest on 1+2 cpu, but ...

copy-on-write and copy-on-demand
4cca7d25 · Frans Kaashoek · 372d4c19 · 4cca7d25 · 4cca7d25 · 4cca7d25
--- a/exec.c
+++ b/exec.c
@@ -21,9 +21,7 @@ exec(char *path, char **argv)
  pde_t *pgdir = 0, *oldpgdir;
  struct vmap *vmap = 0, *oldvmap;
  struct vmnode *vmn = 0;
-  int odp = 0;
-
-  cprintf("exec: %s\n", path);
+  int odp = 1;

  if((ip = namei(path)) == 0)
    return -1;

--- a/proc.c
+++ b/proc.c
@@ -205,6 +205,8 @@ fork(int flags)
  struct proc *np;
  uint cow = 1;

+  //  cprintf("%d: fork\n", proc->pid);
+
  // Allocate process.
  if((np = allocproc()) == 0)
    return -1;
@@ -249,6 +251,7 @@ fork(int flags)
  acquire(&proc->lock);
  SLIST_INSERT_HEAD(&proc->childq, np, child_next);
  release(&proc->lock);
+  //  cprintf("%d: fork done (pid %d)\n", proc->pid, pid);
  return pid;
 }


--- a/vm.c
+++ b/vm.c
@@ -246,6 +246,8 @@ vmn_alloc(uint npg, uint type)
      if(npg > sizeof(n->page) / sizeof(n->page[0])) {
 	panic("vmnode too big\n");
      }
+      for (uint i = 0; i < sizeof(n->page) / sizeof(n->page[0]); i++) 
+	n->page[i] = 0;
      n->npages = npg;
      n->ref = 0;
      n->ip = 0;
@@ -288,7 +290,8 @@ vmn_free(struct vmnode *n)
    }
  }
  if (n->ip)
-    panic("vmn_free: drop inode ref");
+    iput(n->ip);
+  n->ip = 0;
  n->alloc = 0;
 }

@@ -302,12 +305,23 @@ vmn_decref(struct vmnode *n)
 struct vmnode *
 vmn_copy(struct vmnode *n)
 {
-  struct vmnode *c = vmn_allocpg(n->npages);
+  struct vmnode *c = vmn_alloc(n->npages, n->type);
  if(c != 0) {
+    c->type = n->type;
+    if (n->type == ONDEMAND) {
+      c->ip = idup(n->ip);
+      c->offset = n->offset;
+      c->sz = c->sz;
+    } 
+    if (n->page[0]) {   // If the first page is present, all of them are present
+      if (vmn_doallocpg(c) < 0) {
+	panic("vmn_copy\n");
+      }
      for(uint i = 0; i < n->npages; i++) {
 	memmove(c->page[i], n->page[i], PGSIZE);
      }
    }
+  }
  return c;
 }

@@ -558,8 +572,8 @@ pagefault(pde_t *pgdir, struct vmap *vmap, uint va, uint err)
  // cprintf("%d: pf vma type = %d refcnt %d  vmn type %d pte=0x%x\n", proc->pid, m->va_type, m->n->ref, m->n->type, *pte);

  uint npg = (PGROUNDDOWN(va) - m->va_start) / PGSIZE;
-  if (m->n && m->n->ip && *pte == 0x0) {
-    //cprintf("ODP\n");
+  if (m->n && m->n->ip && *pte == 0x0 && m->n->page[npg] == 0) {
+    //    cprintf("ODP\n");
    if (vmn_doallocpg(m->n) < 0) {
      panic("pagefault: couldn't allocate pages");
    }
@@ -571,7 +585,7 @@ pagefault(pde_t *pgdir, struct vmap *vmap, uint va, uint err)
    pte = walkpgdir(pgdir, (const void *)va, 0);
    if (pte == 0x0)
      panic("pagefault: not paged in???");
-    cprintf("ODP done\n");
+    // cprintf("ODP done\n");
  }

  if (m->va_type == COW && (err & FEC_WR)) {
@@ -606,6 +620,3 @@ pagefault(pde_t *pgdir, struct vmap *vmap, uint va, uint err)
  release(&m->lock);
  return 1;
 }
-
-
-