svn commit: r304102 - in head/sys: kern vm

[Alan Cox]

Author: alc
Date: Sun Aug 14 22:00:45 2016
New Revision: 304102
URL: https://svnweb.freebsd.org/changeset/base/304102

Log:
  Eliminate unneeded vm_page_xbusy() and vm_page_xunbusy() operations when
  neither vm_pager_has_page() nor vm_pager_get_pages() is called.
  
  Reviewed by:	kib, markj
  MFC after:	3 weeks

Modified:
  head/sys/kern/kern_exec.c
  head/sys/kern/uipc_shm.c
  head/sys/vm/vm_glue.c

Modified: head/sys/kern/kern_exec.c
==============================================================================
--- head/sys/kern/kern_exec.c	Sun Aug 14 20:22:03 2016	(r304101)
+++ head/sys/kern/kern_exec.c	Sun Aug 14 22:00:45 2016	(r304102)
@@ -984,8 +984,9 @@ exec_map_first_page(imgp)
 #if VM_NRESERVLEVEL > 0
 	vm_object_color(object, 0);
 #endif
-	ma[0] = vm_page_grab(object, 0, VM_ALLOC_NORMAL);
+	ma[0] = vm_page_grab(object, 0, VM_ALLOC_NORMAL | VM_ALLOC_NOBUSY);
 	if (ma[0]->valid != VM_PAGE_BITS_ALL) {
+		vm_page_xbusy(ma[0]);
 		if (!vm_pager_has_page(object, 0, NULL, &after)) {
 			vm_page_lock(ma[0]);
 			vm_page_free(ma[0]);
@@ -1021,10 +1022,10 @@ exec_map_first_page(imgp)
 			VM_OBJECT_WUNLOCK(object);
 			return (EIO);
 		}
+		vm_page_xunbusy(ma[0]);
 		for (i = 1; i < initial_pagein; i++)
 			vm_page_readahead_finish(ma[i]);
 	}
-	vm_page_xunbusy(ma[0]);
 	vm_page_lock(ma[0]);
 	vm_page_hold(ma[0]);
 	vm_page_activate(ma[0]);

Modified: head/sys/kern/uipc_shm.c
==============================================================================
--- head/sys/kern/uipc_shm.c	Sun Aug 14 20:22:03 2016	(r304101)
+++ head/sys/kern/uipc_shm.c	Sun Aug 14 22:00:45 2016	(r304102)
@@ -182,8 +182,9 @@ uiomove_object_page(vm_object_t obj, siz
 	 * lock to page out tobj's pages because tobj is a OBJT_SWAP
 	 * type object.
 	 */
-	m = vm_page_grab(obj, idx, VM_ALLOC_NORMAL);
+	m = vm_page_grab(obj, idx, VM_ALLOC_NORMAL | VM_ALLOC_NOBUSY);
 	if (m->valid != VM_PAGE_BITS_ALL) {
+		vm_page_xbusy(m);
 		if (vm_pager_has_page(obj, idx, NULL, NULL)) {
 			rv = vm_pager_get_pages(obj, &m, 1, NULL, NULL);
 			if (rv != VM_PAGER_OK) {
@@ -198,8 +199,8 @@ uiomove_object_page(vm_object_t obj, siz
 			}
 		} else
 			vm_page_zero_invalid(m, TRUE);
+		vm_page_xunbusy(m);
 	}
-	vm_page_xunbusy(m);
 	vm_page_lock(m);
 	vm_page_hold(m);
 	if (m->queue == PQ_NONE) {

Modified: head/sys/vm/vm_glue.c
==============================================================================
--- head/sys/vm/vm_glue.c	Sun Aug 14 20:22:03 2016	(r304101)
+++ head/sys/vm/vm_glue.c	Sun Aug 14 22:00:45 2016	(r304102)
@@ -236,8 +236,9 @@ vm_imgact_hold_page(vm_object_t object, 
 
 	VM_OBJECT_WLOCK(object);
 	pindex = OFF_TO_IDX(offset);
-	m = vm_page_grab(object, pindex, VM_ALLOC_NORMAL);
+	m = vm_page_grab(object, pindex, VM_ALLOC_NORMAL | VM_ALLOC_NOBUSY);
 	if (m->valid != VM_PAGE_BITS_ALL) {
+		vm_page_xbusy(m);
 		rv = vm_pager_get_pages(object, &m, 1, NULL, NULL);
 		if (rv != VM_PAGER_OK) {
 			vm_page_lock(m);
@@ -246,8 +247,8 @@ vm_imgact_hold_page(vm_object_t object, 
 			m = NULL;
 			goto out;
 		}
+		vm_page_xunbusy(m);
 	}
-	vm_page_xunbusy(m);
 	vm_page_lock(m);
 	vm_page_hold(m);
 	vm_page_activate(m);