svn commit: r351569 - in head/sys: kern vm

Mark Johnston markj at FreeBSD.org
Wed Aug 28 16:08:07 UTC 2019


Author: markj
Date: Wed Aug 28 16:08:06 2019
New Revision: 351569
URL: https://svnweb.freebsd.org/changeset/base/351569

Log:
  Wire pages in vm_page_grab() when appropriate.
  
  uiomove_object_page() and exec_map_first_page() would previously wire a
  page after having grabbed it.  Ask vm_page_grab() to perform the wiring
  instead: this removes some redundant code, and is cheaper in the case
  where the requested page is not resident since the page allocator can be
  asked to initialize the page as wired, whereas a separate vm_page_wire()
  call requires the page lock.
  
  In vm_imgact_hold_page(), use vm_page_unwire_noq() instead of
  vm_page_unwire(PQ_NONE).  The latter ensures that the page is dequeued
  before returning, but this is unnecessary since vm_page_free() will
  trigger a batched dequeue of the page.
  
  Reviewed by:	alc, kib
  Tested by:	pho (part of a larger patch)
  MFC after:	1 week
  Sponsored by:	Netflix
  Differential Revision:	https://reviews.freebsd.org/D21440

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	Wed Aug 28 08:09:10 2019	(r351568)
+++ head/sys/kern/kern_exec.c	Wed Aug 28 16:08:06 2019	(r351569)
@@ -972,11 +972,13 @@ exec_map_first_page(struct image_params *imgp)
 #if VM_NRESERVLEVEL > 0
 	vm_object_color(object, 0);
 #endif
-	ma[0] = vm_page_grab(object, 0, VM_ALLOC_NORMAL | VM_ALLOC_NOBUSY);
+	ma[0] = vm_page_grab(object, 0, VM_ALLOC_NORMAL | VM_ALLOC_NOBUSY |
+	    VM_ALLOC_WIRED);
 	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_unwire_noq(ma[0]);
 			vm_page_free(ma[0]);
 			vm_page_unlock(ma[0]);
 			VM_OBJECT_WUNLOCK(object);
@@ -1004,6 +1006,8 @@ exec_map_first_page(struct image_params *imgp)
 		if (rv != VM_PAGER_OK) {
 			for (i = 0; i < initial_pagein; i++) {
 				vm_page_lock(ma[i]);
+				if (i == 0)
+					vm_page_unwire_noq(ma[i]);
 				vm_page_free(ma[i]);
 				vm_page_unlock(ma[i]);
 			}
@@ -1014,9 +1018,6 @@ exec_map_first_page(struct image_params *imgp)
 		for (i = 1; i < initial_pagein; i++)
 			vm_page_readahead_finish(ma[i]);
 	}
-	vm_page_lock(ma[0]);
-	vm_page_wire(ma[0]);
-	vm_page_unlock(ma[0]);
 	VM_OBJECT_WUNLOCK(object);
 
 	imgp->firstpage = sf_buf_alloc(ma[0], 0);

Modified: head/sys/kern/uipc_shm.c
==============================================================================
--- head/sys/kern/uipc_shm.c	Wed Aug 28 08:09:10 2019	(r351568)
+++ head/sys/kern/uipc_shm.c	Wed Aug 28 16:08:06 2019	(r351569)
@@ -188,7 +188,8 @@ uiomove_object_page(vm_object_t obj, size_t len, struc
 	 * lock to page out tobj's pages because tobj is a OBJT_SWAP
 	 * type object.
 	 */
-	m = vm_page_grab(obj, idx, VM_ALLOC_NORMAL | VM_ALLOC_NOBUSY);
+	m = vm_page_grab(obj, idx, VM_ALLOC_NORMAL | VM_ALLOC_NOBUSY |
+	    VM_ALLOC_WIRED);
 	if (m->valid != VM_PAGE_BITS_ALL) {
 		vm_page_xbusy(m);
 		if (vm_pager_has_page(obj, idx, NULL, NULL)) {
@@ -198,6 +199,7 @@ uiomove_object_page(vm_object_t obj, size_t len, struc
 	    "uiomove_object: vm_obj %p idx %jd valid %x pager error %d\n",
 				    obj, idx, m->valid, rv);
 				vm_page_lock(m);
+				vm_page_unwire_noq(m);
 				vm_page_free(m);
 				vm_page_unlock(m);
 				VM_OBJECT_WUNLOCK(obj);
@@ -207,9 +209,6 @@ uiomove_object_page(vm_object_t obj, size_t len, struc
 			vm_page_zero_invalid(m, TRUE);
 		vm_page_xunbusy(m);
 	}
-	vm_page_lock(m);
-	vm_page_wire(m);
-	vm_page_unlock(m);
 	VM_OBJECT_WUNLOCK(obj);
 	error = uiomove_fromphys(&m, offset, tlen, uio);
 	if (uio->uio_rw == UIO_WRITE && error == 0) {

Modified: head/sys/vm/vm_glue.c
==============================================================================
--- head/sys/vm/vm_glue.c	Wed Aug 28 08:09:10 2019	(r351568)
+++ head/sys/vm/vm_glue.c	Wed Aug 28 16:08:06 2019	(r351569)
@@ -230,7 +230,7 @@ vm_imgact_hold_page(vm_object_t object, vm_ooffset_t o
 		rv = vm_pager_get_pages(object, &m, 1, NULL, NULL);
 		if (rv != VM_PAGER_OK) {
 			vm_page_lock(m);
-			vm_page_unwire(m, PQ_NONE);
+			vm_page_unwire_noq(m);
 			vm_page_free(m);
 			vm_page_unlock(m);
 			m = NULL;


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