Migrate pmap_prefault() into the machine-independent virtual memory layer.

A small helper function pmap_is_prefaultable() is added.  This function
encapsulate the few lines of pmap_prefault() that actually vary from
machine to machine.  Note: pmap_is_prefaultable() and pmap_mincore() have
much in common.  Going forward, it's worth considering their merger.

10 files changed, 221 insertions, 424 deletions

diff --git a/sys/alpha/alpha/pmap.c b/sys/alpha/alpha/pmap.c
index 82ab789..1133ad2 100644
--- a/sys/alpha/alpha/pmap.c
+++ b/sys/alpha/alpha/pmap.c
@@ -2093,105 +2093,6 @@ pmap_object_init_pt(pmap_t pmap, vm_offset_t addr,
 }
 
 /*
- * pmap_prefault provides a quick way of clustering
- * pagefaults into a processes address space.  It is a "cousin"
- * of pmap_object_init_pt, except it runs at page fault time instead
- * of mmap time.
- */
-#define PFBAK 4
-#define PFFOR 4
-#define PAGEORDER_SIZE (PFBAK+PFFOR)
-
-static int pmap_prefault_pageorder[] = {
-	-1 * PAGE_SIZE, 1 * PAGE_SIZE,
-	-2 * PAGE_SIZE, 2 * PAGE_SIZE,
-	-3 * PAGE_SIZE, 3 * PAGE_SIZE,
-	-4 * PAGE_SIZE, 4 * PAGE_SIZE
-};
-
-void
-pmap_prefault(pmap, addra, entry)
-	pmap_t pmap;
-	vm_offset_t addra;
-	vm_map_entry_t entry;
-{
-	int i;
-	vm_offset_t starta;
-	vm_offset_t addr;
-	vm_pindex_t pindex;
-	vm_page_t m, mpte;
-	vm_object_t object;
-
-	if (!curthread || (pmap != vmspace_pmap(curthread->td_proc->p_vmspace)))
-		return;
-
-	object = entry->object.vm_object;
-
-	starta = addra - PFBAK * PAGE_SIZE;
-	if (starta < entry->start) {
-		starta = entry->start;
-	} else if (starta > addra) {
-		starta = 0;
-	}
-
-	mpte = NULL;
-	for (i = 0; i < PAGEORDER_SIZE; i++) {
-		vm_object_t backing_object, lobject;
-		pt_entry_t *pte;
-
-		addr = addra + pmap_prefault_pageorder[i];
-		if (addr > addra + (PFFOR * PAGE_SIZE))
-			addr = 0;
-
-		if (addr < starta || addr >= entry->end)
-			continue;
-
-		if (!pmap_pte_v(pmap_lev1pte(pmap, addr))
-		    || !pmap_pte_v(pmap_lev2pte(pmap, addr)))
-			continue;
-
-		pte = vtopte(addr);
-		if (*pte)
-			continue;
-
-		pindex = ((addr - entry->start) + entry->offset) >> PAGE_SHIFT;
-		lobject = object;
-		VM_OBJECT_LOCK(lobject);
-		while ((m = vm_page_lookup(lobject, pindex)) == NULL &&
-		    lobject->type == OBJT_DEFAULT &&
-		    (backing_object = lobject->backing_object) != NULL) {
-			if (lobject->backing_object_offset & PAGE_MASK)
-				break;
-			pindex += lobject->backing_object_offset >> PAGE_SHIFT;
-			VM_OBJECT_LOCK(backing_object);
-			VM_OBJECT_UNLOCK(lobject);
-			lobject = backing_object;
-		}
-		VM_OBJECT_UNLOCK(lobject);
-		/*
-		 * give-up when a page is not in memory
-		 */
-		if (m == NULL)
-			break;
-		vm_page_lock_queues();
-		if (((m->valid & VM_PAGE_BITS_ALL) == VM_PAGE_BITS_ALL) &&
-			(m->busy == 0) &&
-		    (m->flags & (PG_BUSY | PG_FICTITIOUS)) == 0) {
-
-			if ((m->queue - m->pc) == PQ_CACHE) {
-				vm_page_deactivate(m);
-			}
-			vm_page_busy(m);
-			vm_page_unlock_queues();
-			mpte = pmap_enter_quick(pmap, addr, m, mpte);
-			vm_page_lock_queues();
-			vm_page_wakeup(m);
-		}
-		vm_page_unlock_queues();
-	}
-}
-
-/*
  *	Routine:	pmap_change_wiring
  *	Function:	Change the wiring attribute for a map/virtual-address
  *			pair.
@@ -2557,6 +2458,26 @@ pmap_is_modified(vm_page_t m)
 }
 
 /*
+ *	pmap_is_prefaultable:
+ *
+ *	Return whether or not the specified virtual address is elgible
+ *	for prefault.
+ */
+boolean_t
+pmap_is_prefaultable(pmap_t pmap, vm_offset_t addr)
+{
+	pt_entry_t *pte;
+
+	if (!pmap_pte_v(pmap_lev1pte(pmap, addr)) ||
+	    !pmap_pte_v(pmap_lev2pte(pmap, addr)))
+		return (FALSE);
+	pte = vtopte(addr);
+	if (*pte)
+		return (FALSE);
+	return (TRUE);
+}
+
+/*
  *	Clear the modify bits on the specified physical page.
  */
 void
diff --git a/sys/amd64/amd64/pmap.c b/sys/amd64/amd64/pmap.c
index d991c26..2e70b52 100644
--- a/sys/amd64/amd64/pmap.c
+++ b/sys/amd64/amd64/pmap.c
@@ -2124,106 +2124,6 @@ retry:
 }
 
 /*
- * pmap_prefault provides a quick way of clustering
- * pagefaults into a processes address space.  It is a "cousin"
- * of pmap_object_init_pt, except it runs at page fault time instead
- * of mmap time.
- */
-#define PFBAK 4
-#define PFFOR 4
-#define PAGEORDER_SIZE (PFBAK+PFFOR)
-
-static int pmap_prefault_pageorder[] = {
-	-1 * PAGE_SIZE, 1 * PAGE_SIZE,
-	-2 * PAGE_SIZE, 2 * PAGE_SIZE,
-	-3 * PAGE_SIZE, 3 * PAGE_SIZE,
-	-4 * PAGE_SIZE, 4 * PAGE_SIZE
-};
-
-void
-pmap_prefault(pmap, addra, entry)
-	pmap_t pmap;
-	vm_offset_t addra;
-	vm_map_entry_t entry;
-{
-	int i;
-	vm_offset_t starta;
-	vm_offset_t addr;
-	vm_pindex_t pindex;
-	vm_page_t m, mpte;
-	vm_object_t object;
-	pd_entry_t *pde;
-
-	if (!curthread || (pmap != vmspace_pmap(curthread->td_proc->p_vmspace)))
-		return;
-
-	object = entry->object.vm_object;
-
-	starta = addra - PFBAK * PAGE_SIZE;
-	if (starta < entry->start) {
-		starta = entry->start;
-	} else if (starta > addra) {
-		starta = 0;
-	}
-
-	mpte = NULL;
-	for (i = 0; i < PAGEORDER_SIZE; i++) {
-		vm_object_t backing_object, lobject;
-		pt_entry_t *pte;
-
-		addr = addra + pmap_prefault_pageorder[i];
-		if (addr > addra + (PFFOR * PAGE_SIZE))
-			addr = 0;
-
-		if (addr < starta || addr >= entry->end)
-			continue;
-
-		pde = pmap_pde(pmap, addr);
-		if (pde == NULL || (*pde & PG_V) == 0) 
-			continue;
-
-		pte = vtopte(addr);
-		if ((*pte & PG_V) == 0)
-			continue;
-
-		pindex = ((addr - entry->start) + entry->offset) >> PAGE_SHIFT;
-		lobject = object;
-		VM_OBJECT_LOCK(lobject);
-		while ((m = vm_page_lookup(lobject, pindex)) == NULL &&
-		    lobject->type == OBJT_DEFAULT &&
-		    (backing_object = lobject->backing_object) != NULL) {
-			if (lobject->backing_object_offset & PAGE_MASK)
-				break;
-			pindex += lobject->backing_object_offset >> PAGE_SHIFT;
-			VM_OBJECT_LOCK(backing_object);
-			VM_OBJECT_UNLOCK(lobject);
-			lobject = backing_object;
-		}
-		VM_OBJECT_UNLOCK(lobject);
-		/*
-		 * give-up when a page is not in memory
-		 */
-		if (m == NULL)
-			break;
-		vm_page_lock_queues();
-		if (((m->valid & VM_PAGE_BITS_ALL) == VM_PAGE_BITS_ALL) &&
-			(m->busy == 0) &&
-		    (m->flags & (PG_BUSY | PG_FICTITIOUS)) == 0) {
-
-			if ((m->queue - m->pc) == PQ_CACHE) {
-				vm_page_deactivate(m);
-			}
-			vm_page_busy(m);
-			vm_page_unlock_queues();
-			mpte = pmap_enter_quick(pmap, addr, m, mpte);
-			vm_page_lock_queues();
-			vm_page_wakeup(m);
-		}
-		vm_page_unlock_queues();
-	}
-}
-
-/*
  *	Routine:	pmap_change_wiring
  *	Function:	Change the wiring attribute for a map/virtual-address
  *			pair.
@@ -2598,6 +2498,27 @@ pmap_is_modified(vm_page_t m)
 }
 
 /*
+ *	pmap_is_prefaultable:
+ *
+ *	Return whether or not the specified virtual address is elgible
+ *	for prefault.
+ */
+boolean_t
+pmap_is_prefaultable(pmap_t pmap, vm_offset_t addr)
+{
+	pd_entry_t *pde;
+	pt_entry_t *pte;
+
+	pde = pmap_pde(pmap, addr);
+	if (pde == NULL || (*pde & PG_V) == 0) 
+		return (FALSE);
+	pte = vtopte(addr);
+	if ((*pte & PG_V) == 0)
+		return (FALSE);
+	return (TRUE);
+}
+
+/*
  *	Clear the given bit in each of the given page's ptes.
  */
 static __inline void
diff --git a/sys/i386/i386/pmap.c b/sys/i386/i386/pmap.c
index f1ce5a3..d070f90 100644
--- a/sys/i386/i386/pmap.c
+++ b/sys/i386/i386/pmap.c
@@ -2192,104 +2192,6 @@ retry:
 }
 
 /*
- * pmap_prefault provides a quick way of clustering
- * pagefaults into a processes address space.  It is a "cousin"
- * of pmap_object_init_pt, except it runs at page fault time instead
- * of mmap time.
- */
-#define PFBAK 4
-#define PFFOR 4
-#define PAGEORDER_SIZE (PFBAK+PFFOR)
-
-static int pmap_prefault_pageorder[] = {
-	-1 * PAGE_SIZE, 1 * PAGE_SIZE,
-	-2 * PAGE_SIZE, 2 * PAGE_SIZE,
-	-3 * PAGE_SIZE, 3 * PAGE_SIZE,
-	-4 * PAGE_SIZE, 4 * PAGE_SIZE
-};
-
-void
-pmap_prefault(pmap, addra, entry)
-	pmap_t pmap;
-	vm_offset_t addra;
-	vm_map_entry_t entry;
-{
-	int i;
-	vm_offset_t starta;
-	vm_offset_t addr;
-	vm_pindex_t pindex;
-	vm_page_t m, mpte;
-	vm_object_t object;
-
-	if (!curthread || (pmap != vmspace_pmap(curthread->td_proc->p_vmspace)))
-		return;
-
-	object = entry->object.vm_object;
-
-	starta = addra - PFBAK * PAGE_SIZE;
-	if (starta < entry->start) {
-		starta = entry->start;
-	} else if (starta > addra) {
-		starta = 0;
-	}
-
-	mpte = NULL;
-	for (i = 0; i < PAGEORDER_SIZE; i++) {
-		vm_object_t backing_object, lobject;
-		pt_entry_t *pte;
-
-		addr = addra + pmap_prefault_pageorder[i];
-		if (addr > addra + (PFFOR * PAGE_SIZE))
-			addr = 0;
-
-		if (addr < starta || addr >= entry->end)
-			continue;
-
-		if ((*pmap_pde(pmap, addr)) == 0) 
-			continue;
-
-		pte = vtopte(addr);
-		if (*pte)
-			continue;
-
-		pindex = ((addr - entry->start) + entry->offset) >> PAGE_SHIFT;
-		lobject = object;
-		VM_OBJECT_LOCK(lobject);
-		while ((m = vm_page_lookup(lobject, pindex)) == NULL &&
-		    lobject->type == OBJT_DEFAULT &&
-		    (backing_object = lobject->backing_object) != NULL) {
-			if (lobject->backing_object_offset & PAGE_MASK)
-				break;
-			pindex += lobject->backing_object_offset >> PAGE_SHIFT;
-			VM_OBJECT_LOCK(backing_object);
-			VM_OBJECT_UNLOCK(lobject);
-			lobject = backing_object;
-		}
-		VM_OBJECT_UNLOCK(lobject);
-		/*
-		 * give-up when a page is not in memory
-		 */
-		if (m == NULL)
-			break;
-		vm_page_lock_queues();
-		if (((m->valid & VM_PAGE_BITS_ALL) == VM_PAGE_BITS_ALL) &&
-			(m->busy == 0) &&
-		    (m->flags & (PG_BUSY | PG_FICTITIOUS)) == 0) {
-
-			if ((m->queue - m->pc) == PQ_CACHE) {
-				vm_page_deactivate(m);
-			}
-			vm_page_busy(m);
-			vm_page_unlock_queues();
-			mpte = pmap_enter_quick(pmap, addr, m, mpte);
-			vm_page_lock_queues();
-			vm_page_wakeup(m);
-		}
-		vm_page_unlock_queues();
-	}
-}
-
-/*
  *	Routine:	pmap_change_wiring
  *	Function:	Change the wiring attribute for a map/virtual-address
  *			pair.
@@ -2764,6 +2666,25 @@ pmap_is_modified(vm_page_t m)
 }
 
 /*
+ *	pmap_is_prefaultable:
+ *
+ *	Return whether or not the specified virtual address is elgible
+ *	for prefault.
+ */
+boolean_t
+pmap_is_prefaultable(pmap_t pmap, vm_offset_t addr)
+{
+	pt_entry_t *pte;
+
+	if ((*pmap_pde(pmap, addr)) == 0) 
+		return (FALSE);
+	pte = vtopte(addr);
+	if (*pte)
+		return (FALSE);
+	return (TRUE);
+}
+
+/*
  *	Clear the given bit in each of the given page's ptes.
  */
 static __inline void
diff --git a/sys/ia64/ia64/pmap.c b/sys/ia64/ia64/pmap.c
index a404707..40400cf 100644
--- a/sys/ia64/ia64/pmap.c
+++ b/sys/ia64/ia64/pmap.c
@@ -1736,101 +1736,6 @@ pmap_object_init_pt(pmap_t pmap, vm_offset_t addr,
 }
 
 /*
- * pmap_prefault provides a quick way of clustering
- * pagefaults into a processes address space.  It is a "cousin"
- * of pmap_object_init_pt, except it runs at page fault time instead
- * of mmap time.
- */
-#define PFBAK 4
-#define PFFOR 4
-#define PAGEORDER_SIZE (PFBAK+PFFOR)
-
-static int pmap_prefault_pageorder[] = {
-	-1 * PAGE_SIZE, 1 * PAGE_SIZE,
-	-2 * PAGE_SIZE, 2 * PAGE_SIZE,
-	-3 * PAGE_SIZE, 3 * PAGE_SIZE,
-	-4 * PAGE_SIZE, 4 * PAGE_SIZE
-};
-
-void
-pmap_prefault(pmap, addra, entry)
-	pmap_t pmap;
-	vm_offset_t addra;
-	vm_map_entry_t entry;
-{
-	int i;
-	vm_offset_t starta;
-	vm_offset_t addr;
-	vm_pindex_t pindex;
-	vm_page_t m, mpte;
-	vm_object_t object;
-
-	if (!curthread || (pmap != vmspace_pmap(curthread->td_proc->p_vmspace)))
-		return;
-
-	object = entry->object.vm_object;
-
-	starta = addra - PFBAK * PAGE_SIZE;
-	if (starta < entry->start) {
-		starta = entry->start;
-	} else if (starta > addra) {
-		starta = 0;
-	}
-
-	mpte = NULL;
-	for (i = 0; i < PAGEORDER_SIZE; i++) {
-		vm_object_t backing_object, lobject;
-		struct ia64_lpte *pte;
-
-		addr = addra + pmap_prefault_pageorder[i];
-		if (addr > addra + (PFFOR * PAGE_SIZE))
-			addr = 0;
-
-		if (addr < starta || addr >= entry->end)
-			continue;
-
-		pte = pmap_find_vhpt(addr);
-		if (pte && pte->pte_p)
-			continue;
-
-		pindex = ((addr - entry->start) + entry->offset) >> PAGE_SHIFT;
-		lobject = object;
-		VM_OBJECT_LOCK(lobject);
-		while ((m = vm_page_lookup(lobject, pindex)) == NULL &&
-		    lobject->type == OBJT_DEFAULT &&
-		    (backing_object = lobject->backing_object) != NULL) {
-			if (lobject->backing_object_offset & PAGE_MASK)
-				break;
-			pindex += lobject->backing_object_offset >> PAGE_SHIFT;
-			VM_OBJECT_LOCK(backing_object);
-			VM_OBJECT_UNLOCK(lobject);
-			lobject = backing_object;
-		}
-		VM_OBJECT_UNLOCK(lobject);
-		/*
-		 * give-up when a page is not in memory
-		 */
-		if (m == NULL)
-			break;
-		vm_page_lock_queues();
-		if (((m->valid & VM_PAGE_BITS_ALL) == VM_PAGE_BITS_ALL) &&
-			(m->busy == 0) &&
-		    (m->flags & (PG_BUSY | PG_FICTITIOUS)) == 0) {
-
-			if ((m->queue - m->pc) == PQ_CACHE) {
-				vm_page_deactivate(m);
-			}
-			vm_page_busy(m);
-			vm_page_unlock_queues();
-			pmap_enter_quick(pmap, addr, m, NULL);
-			vm_page_lock_queues();
-			vm_page_wakeup(m);
-		}
-		vm_page_unlock_queues();
-	}
-}
-
-/*
  *	Routine:	pmap_change_wiring
  *	Function:	Change the wiring attribute for a map/virtual-address
  *			pair.
@@ -2148,6 +2053,23 @@ pmap_is_modified(vm_page_t m)
 }
 
 /*
+ *	pmap_is_prefaultable:
+ *
+ *	Return whether or not the specified virtual address is elgible
+ *	for prefault.
+ */
+boolean_t
+pmap_is_prefaultable(pmap_t pmap, vm_offset_t addr)
+{
+	struct ia64_lpte *pte;
+
+	pte = pmap_find_vhpt(addr);
+	if (pte && pte->pte_p)
+		return (FALSE);
+	return (TRUE);
+}
+
+/*
  *	Clear the modify bits on the specified physical page.
  */
 void
diff --git a/sys/powerpc/aim/mmu_oea.c b/sys/powerpc/aim/mmu_oea.c
index 1c789f7..30ce2f8 100644
--- a/sys/powerpc/aim/mmu_oea.c
+++ b/sys/powerpc/aim/mmu_oea.c
@@ -1117,6 +1117,19 @@ pmap_is_modified(vm_page_t m)
 	return (pmap_query_bit(m, PTE_CHG));
 }
 
+/*
+ *	pmap_is_prefaultable:
+ *
+ *	Return whether or not the specified virtual address is elgible
+ *	for prefault.
+ */
+boolean_t
+pmap_is_prefaultable(pmap_t pmap, vm_offset_t addr)
+{
+
+	return (FALSE);
+}
+
 void
 pmap_clear_reference(vm_page_t m)
 {
@@ -1424,14 +1437,6 @@ pmap_pinit2(pmap_t pmap)
 	/* XXX: Remove this stub when no longer called */
 }
 
-void
-pmap_prefault(pmap_t pm, vm_offset_t va, vm_map_entry_t entry)
-{
-	KASSERT(pm == &curproc->p_vmspace->vm_pmap || pm == kernel_pmap,
-	    ("pmap_prefault: non current pmap"));
-	/* XXX */
-}
-
 /*
  * Set the physical protection on the specified range of this map as requested.
  */
diff --git a/sys/powerpc/powerpc/mmu_oea.c b/sys/powerpc/powerpc/mmu_oea.c
index 1c789f7..30ce2f8 100644
--- a/sys/powerpc/powerpc/mmu_oea.c
+++ b/sys/powerpc/powerpc/mmu_oea.c
@@ -1117,6 +1117,19 @@ pmap_is_modified(vm_page_t m)
 	return (pmap_query_bit(m, PTE_CHG));
 }
 
+/*
+ *	pmap_is_prefaultable:
+ *
+ *	Return whether or not the specified virtual address is elgible
+ *	for prefault.
+ */
+boolean_t
+pmap_is_prefaultable(pmap_t pmap, vm_offset_t addr)
+{
+
+	return (FALSE);
+}
+
 void
 pmap_clear_reference(vm_page_t m)
 {
@@ -1424,14 +1437,6 @@ pmap_pinit2(pmap_t pmap)
 	/* XXX: Remove this stub when no longer called */
 }
 
-void
-pmap_prefault(pmap_t pm, vm_offset_t va, vm_map_entry_t entry)
-{
-	KASSERT(pm == &curproc->p_vmspace->vm_pmap || pm == kernel_pmap,
-	    ("pmap_prefault: non current pmap"));
-	/* XXX */
-}
-
 /*
  * Set the physical protection on the specified range of this map as requested.
  */
diff --git a/sys/powerpc/powerpc/pmap.c b/sys/powerpc/powerpc/pmap.c
index 1c789f7..30ce2f8 100644
--- a/sys/powerpc/powerpc/pmap.c
+++ b/sys/powerpc/powerpc/pmap.c
@@ -1117,6 +1117,19 @@ pmap_is_modified(vm_page_t m)
 	return (pmap_query_bit(m, PTE_CHG));
 }
 
+/*
+ *	pmap_is_prefaultable:
+ *
+ *	Return whether or not the specified virtual address is elgible
+ *	for prefault.
+ */
+boolean_t
+pmap_is_prefaultable(pmap_t pmap, vm_offset_t addr)
+{
+
+	return (FALSE);
+}
+
 void
 pmap_clear_reference(vm_page_t m)
 {
@@ -1424,14 +1437,6 @@ pmap_pinit2(pmap_t pmap)
 	/* XXX: Remove this stub when no longer called */
 }
 
-void
-pmap_prefault(pmap_t pm, vm_offset_t va, vm_map_entry_t entry)
-{
-	KASSERT(pm == &curproc->p_vmspace->vm_pmap || pm == kernel_pmap,
-	    ("pmap_prefault: non current pmap"));
-	/* XXX */
-}
-
 /*
  * Set the physical protection on the specified range of this map as requested.
  */
diff --git a/sys/sparc64/sparc64/pmap.c b/sys/sparc64/sparc64/pmap.c
index a1cbf99..2d7ad37 100644
--- a/sys/sparc64/sparc64/pmap.c
+++ b/sys/sparc64/sparc64/pmap.c
@@ -1374,12 +1374,6 @@ pmap_object_init_pt(pmap_t pm, vm_offset_t addr, vm_object_t object,
 	    ("pmap_object_init_pt: non-device object"));
 }
 
-void
-pmap_prefault(pmap_t pm, vm_offset_t va, vm_map_entry_t entry)
-{
-	/* XXX */
-}
-
 /*
  * Change the wiring attribute for a map/virtual-address pair.
  * The mapping must already exist in the pmap.
@@ -1724,6 +1718,19 @@ pmap_is_modified(vm_page_t m)
 	return (FALSE);
 }
 
+/*
+ *	pmap_is_prefaultable:
+ *
+ *	Return whether or not the specified virtual address is elgible
+ *	for prefault.
+ */
+boolean_t
+pmap_is_prefaultable(pmap_t pmap, vm_offset_t addr)
+{
+
+	return (FALSE);
+}
+
 void
 pmap_clear_modify(vm_page_t m)
 {
diff --git a/sys/vm/pmap.h b/sys/vm/pmap.h
index 8776966..a6eff6ef 100644
--- a/sys/vm/pmap.h
+++ b/sys/vm/pmap.h
@@ -111,6 +111,7 @@ vm_page_t	 pmap_extract_and_hold(pmap_t pmap, vm_offset_t va,
 void		 pmap_growkernel(vm_offset_t);
 void		 pmap_init(vm_paddr_t, vm_paddr_t);
 boolean_t	 pmap_is_modified(vm_page_t m);
+boolean_t	 pmap_is_prefaultable(pmap_t pmap, vm_offset_t va);
 boolean_t	 pmap_ts_referenced(vm_page_t m);
 vm_offset_t	 pmap_map(vm_offset_t *, vm_paddr_t, vm_paddr_t, int);
 void		 pmap_object_init_pt(pmap_t pmap, vm_offset_t addr,
@@ -130,7 +131,6 @@ void		 pmap_remove_pages(pmap_t, vm_offset_t, vm_offset_t);
 void		 pmap_zero_page(vm_page_t);
 void		 pmap_zero_page_area(vm_page_t, int off, int size);
 void		 pmap_zero_page_idle(vm_page_t);
-void		 pmap_prefault(pmap_t, vm_offset_t, vm_map_entry_t);
 int		 pmap_mincore(pmap_t pmap, vm_offset_t addr);
 void		 pmap_activate(struct thread *td);
 vm_offset_t	 pmap_addr_hint(vm_object_t obj, vm_offset_t addr, vm_size_t size);
diff --git a/sys/vm/vm_fault.c b/sys/vm/vm_fault.c
index 855ff71..76fe277 100644
--- a/sys/vm/vm_fault.c
+++ b/sys/vm/vm_fault.c
@@ -97,7 +97,19 @@ __FBSDID("$FreeBSD$");
 #include <vm/vnode_pager.h>
 #include <vm/vm_extern.h>
 
+#define PFBAK 4
+#define PFFOR 4
+#define PAGEORDER_SIZE (PFBAK+PFFOR)
+
+static int prefault_pageorder[] = {
+	-1 * PAGE_SIZE, 1 * PAGE_SIZE,
+	-2 * PAGE_SIZE, 2 * PAGE_SIZE,
+	-3 * PAGE_SIZE, 3 * PAGE_SIZE,
+	-4 * PAGE_SIZE, 4 * PAGE_SIZE
+};
+
 static int vm_fault_additional_pages(vm_page_t, int, int, vm_page_t *, int *);
+static void vm_fault_prefault(pmap_t, vm_offset_t, vm_map_entry_t);
 
 #define VM_FAULT_READ_AHEAD 8
 #define VM_FAULT_READ_BEHIND 7
@@ -889,7 +901,7 @@ readrest:
 	}
 	pmap_enter(fs.map->pmap, vaddr, fs.m, prot, wired);
 	if (((fault_flags & VM_FAULT_WIRE_MASK) == 0) && (wired == 0)) {
-		pmap_prefault(fs.map->pmap, vaddr, fs.entry);
+		vm_fault_prefault(fs.map->pmap, vaddr, fs.entry);
 	}
 	vm_page_lock_queues();
 	vm_page_flag_clear(fs.m, PG_ZERO);
@@ -929,6 +941,84 @@ readrest:
 }
 
 /*
+ * vm_fault_prefault provides a quick way of clustering
+ * pagefaults into a processes address space.  It is a "cousin"
+ * of vm_map_pmap_enter, except it runs at page fault time instead
+ * of mmap time.
+ */
+static void
+vm_fault_prefault(pmap_t pmap, vm_offset_t addra, vm_map_entry_t entry)
+{
+	int i;
+	vm_offset_t addr, starta;
+	vm_pindex_t pindex;
+	vm_page_t m, mpte;
+	vm_object_t object;
+
+	if (!curthread || (pmap != vmspace_pmap(curthread->td_proc->p_vmspace)))
+		return;
+
+	object = entry->object.vm_object;
+
+	starta = addra - PFBAK * PAGE_SIZE;
+	if (starta < entry->start) {
+		starta = entry->start;
+	} else if (starta > addra) {
+		starta = 0;
+	}
+
+	mpte = NULL;
+	for (i = 0; i < PAGEORDER_SIZE; i++) {
+		vm_object_t backing_object, lobject;
+
+		addr = addra + prefault_pageorder[i];
+		if (addr > addra + (PFFOR * PAGE_SIZE))
+			addr = 0;
+
+		if (addr < starta || addr >= entry->end)
+			continue;
+
+		if (!pmap_is_prefaultable(pmap, addr))
+			continue;
+
+		pindex = ((addr - entry->start) + entry->offset) >> PAGE_SHIFT;
+		lobject = object;
+		VM_OBJECT_LOCK(lobject);
+		while ((m = vm_page_lookup(lobject, pindex)) == NULL &&
+		    lobject->type == OBJT_DEFAULT &&
+		    (backing_object = lobject->backing_object) != NULL) {
+			if (lobject->backing_object_offset & PAGE_MASK)
+				break;
+			pindex += lobject->backing_object_offset >> PAGE_SHIFT;
+			VM_OBJECT_LOCK(backing_object);
+			VM_OBJECT_UNLOCK(lobject);
+			lobject = backing_object;
+		}
+		VM_OBJECT_UNLOCK(lobject);
+		/*
+		 * give-up when a page is not in memory
+		 */
+		if (m == NULL)
+			break;
+		vm_page_lock_queues();
+		if (((m->valid & VM_PAGE_BITS_ALL) == VM_PAGE_BITS_ALL) &&
+			(m->busy == 0) &&
+		    (m->flags & (PG_BUSY | PG_FICTITIOUS)) == 0) {
+
+			if ((m->queue - m->pc) == PQ_CACHE) {
+				vm_page_deactivate(m);
+			}
+			vm_page_busy(m);
+			vm_page_unlock_queues();
+			mpte = pmap_enter_quick(pmap, addr, m, mpte);
+			vm_page_lock_queues();
+			vm_page_wakeup(m);
+		}
+		vm_page_unlock_queues();
+	}
+}
+
+/*
  *	vm_fault_quick:
  *
  *	Ensure that the requested virtual address, which may be in userland,