Don't call vm_fault_prefault() on zero-fill faults. It's a waste of time.

Successful prefaults after a zero-fill fault are extremely rare.

1 files changed, 4 insertions, 1 deletions

diff --git a/sys/vm/vm_fault.c b/sys/vm/vm_fault.c
index f8e3c3f8b7e5..4a6495f58ad4 100644
--- a/sys/vm/vm_fault.c
+++ b/sys/vm/vm_fault.c
@@ -652,6 +652,8 @@ vnode_locked:
 			}
 			PCPU_INC(cnt.v_zfod);
 			fs.m->valid = VM_PAGE_BITS_ALL;
+			/* Don't try to prefault neighboring pages. */
+			faultcount = 1;
 			break;	/* break to PAGE HAS BEEN FOUND */
 		} else {
 			KASSERT(fs.object != next_object,
@@ -897,7 +899,8 @@ vnode_locked:
 	 * won't find it (yet).
 	 */
 	pmap_enter(fs.map->pmap, vaddr, fault_type, fs.m, prot, wired);
-	if ((fault_flags & VM_FAULT_CHANGE_WIRING) == 0 && wired == 0)
+	if (faultcount != 1 && (fault_flags & VM_FAULT_CHANGE_WIRING) == 0 &&
+	    wired == 0)
 		vm_fault_prefault(&fs, vaddr, faultcount, reqpage);
 	VM_OBJECT_WLOCK(fs.object);
 	vm_page_lock(fs.m);