Push down the responsibility for zeroing a physical page from the

caller to vm_page_grab().  Although this gives VM_ALLOC_ZERO a
different meaning for vm_page_grab() than for vm_page_alloc(), I feel
such change is necessary to accomplish other goals.  Specifically, I
want to make the PG_ZERO flag immutable between the time it is
allocated by vm_page_alloc() and freed by vm_page_free() or
vm_page_free_zero() to avoid locking overheads.  Once we gave up on
the ability to automatically recognize a zeroed page upon entry to
vm_page_free(), the ability to mutate the PG_ZERO flag became useless.
Instead, I would like to say that "Once a page becomes valid, its
PG_ZERO flag must be ignored."

2 files changed, 0 insertions, 4 deletions

diff --git a/sys/dev/agp/agp.c b/sys/dev/agp/agp.c
index fc4fd1f..f507aa6 100644
--- a/sys/dev/agp/agp.c
+++ b/sys/dev/agp/agp.c
@@ -524,8 +524,6 @@ agp_generic_bind_memory(device_t dev, struct agp_memory *mem,
 		m = vm_page_grab(mem->am_obj, OFF_TO_IDX(i),
 		    VM_ALLOC_WIRED | VM_ALLOC_ZERO | VM_ALLOC_RETRY);
 		VM_OBJECT_UNLOCK(mem->am_obj);
-		if ((m->flags & PG_ZERO) == 0)
-			pmap_zero_page(m);
 		AGP_DPF("found page pa=%#x\n", VM_PAGE_TO_PHYS(m));
 
 		/*
diff --git a/sys/dev/agp/agp_i810.c b/sys/dev/agp/agp_i810.c
index 9210247..30aca50 100644
--- a/sys/dev/agp/agp_i810.c
+++ b/sys/dev/agp/agp_i810.c
@@ -612,8 +612,6 @@ agp_i810_alloc_memory(device_t dev, int type, vm_size_t size)
 		m = vm_page_grab(mem->am_obj, 0,
 		    VM_ALLOC_WIRED | VM_ALLOC_ZERO | VM_ALLOC_RETRY);
 		VM_OBJECT_UNLOCK(mem->am_obj);
-		if ((m->flags & PG_ZERO) == 0)
-			pmap_zero_page(m);
 		vm_page_lock_queues();
 		mem->am_physical = VM_PAGE_TO_PHYS(m);
 		vm_page_wakeup(m);