[src/trunk]: src/sys/rump/librump/rumpkern Don't reorder page on the age queu...

[pooka <pooka%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/29b9b4cc6dcc
branches:  trunk
changeset: 758009:29b9b4cc6dcc
user:      pooka <pooka%NetBSD.org@localhost>
date:      Wed Oct 13 11:01:04 2010 +0000

description:
Don't reorder page on the age queue if the lookup is done by the
pagedaemon.  This mimics normal kernel behaviour where pmap_kentered
mappings are not tracked for references.  Without this change the
vnode pager's clustering could cause one page to be released by
the pagedaemon, and the rest of the pages in the pageout cluster
made unlikely candidates to be released soon.

diffstat:

 sys/rump/librump/rumpkern/vm.c |  17 +++++++++++++----
 1 files changed, 13 insertions(+), 4 deletions(-)

diffs (44 lines):

diff -r 5e5f39e030f7 -r 29b9b4cc6dcc sys/rump/librump/rumpkern/vm.c
--- a/sys/rump/librump/rumpkern/vm.c    Wed Oct 13 10:56:56 2010 +0000
+++ b/sys/rump/librump/rumpkern/vm.c    Wed Oct 13 11:01:04 2010 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: vm.c,v 1.96 2010/09/24 22:51:51 rmind Exp $    */
+/*     $NetBSD: vm.c,v 1.97 2010/10/13 11:01:04 pooka Exp $    */
 
 /*
  * Copyright (c) 2007-2010 Antti Kantee.  All Rights Reserved.
@@ -41,7 +41,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: vm.c,v 1.96 2010/09/24 22:51:51 rmind Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vm.c,v 1.97 2010/10/13 11:01:04 pooka Exp $");
 
 #include <sys/param.h>
 #include <sys/atomic.h>
@@ -464,14 +464,23 @@
        return pg;
 }
 
-/* Called with the vm object locked */
+/*
+ * Called with the vm object locked.
+ *
+ * Put vnode object pages at the end of the access queue to indicate
+ * they have been recently accessed and should not be immediate
+ * candidates for pageout.  Do not do this for lookups done by
+ * the pagedaemon to mimic pmap_kentered mappings which don't track
+ * access information.
+ */
 struct vm_page *
 uvm_pagelookup(struct uvm_object *uobj, voff_t off)
 {
        struct vm_page *pg;
+       bool ispagedaemon = curlwp == uvm.pagedaemon_lwp;
 
        pg = rb_tree_find_node(&uobj->rb_tree, &off);
-       if (pg && !UVM_OBJ_IS_AOBJ(pg->uobject)) {
+       if (pg && !UVM_OBJ_IS_AOBJ(pg->uobject) && !ispagedaemon) {
                mutex_enter(&uvm_pageqlock);
                TAILQ_REMOVE(&vmpage_lruqueue, pg, pageq.queue);
                TAILQ_INSERT_TAIL(&vmpage_lruqueue, pg, pageq.queue);