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authoralc <alc@FreeBSD.org>2010-05-02 17:33:46 +0000
committeralc <alc@FreeBSD.org>2010-05-02 17:33:46 +0000
commitf35e97166b133de28351ffee3f6de3407d0272b7 (patch)
tree800dba3ed92fa905f4e1acbc91746a06e2e47bc9 /sys/fs
parent1b4eb78965d8d551d4997edd6125fd401a212f5b (diff)
downloadFreeBSD-src-f35e97166b133de28351ffee3f6de3407d0272b7.zip
FreeBSD-src-f35e97166b133de28351ffee3f6de3407d0272b7.tar.gz
It makes no sense for vm_page_sleep_if_busy()'s helper, vm_page_sleep(),
to unconditionally set PG_REFERENCED on a page before sleeping. In many cases, it's perfectly ok for the page to disappear, i.e., be reclaimed by the page daemon, before the caller to vm_page_sleep() is reawakened. Instead, we now explicitly set PG_REFERENCED in those cases where having the page persist until the caller is awakened is clearly desirable. Note, however, that setting PG_REFERENCED on the page is still only a hint, and not a guarantee that the page should persist.
Diffstat (limited to 'sys/fs')
-rw-r--r--sys/fs/tmpfs/tmpfs_vnops.c30
1 files changed, 27 insertions, 3 deletions
diff --git a/sys/fs/tmpfs/tmpfs_vnops.c b/sys/fs/tmpfs/tmpfs_vnops.c
index c17efff..3d3755d 100644
--- a/sys/fs/tmpfs/tmpfs_vnops.c
+++ b/sys/fs/tmpfs/tmpfs_vnops.c
@@ -516,8 +516,16 @@ tmpfs_mappedread(vm_object_t vobj, vm_object_t tobj, size_t len, struct uio *uio
lookupvpg:
if (((m = vm_page_lookup(vobj, idx)) != NULL) &&
vm_page_is_valid(m, offset, tlen)) {
- if (vm_page_sleep_if_busy(m, FALSE, "tmfsmr"))
+ if ((m->oflags & VPO_BUSY) != 0) {
+ /*
+ * Reference the page before unlocking and sleeping so
+ * that the page daemon is less likely to reclaim it.
+ */
+ vm_page_lock_queues();
+ vm_page_flag_set(m, PG_REFERENCED);
+ vm_page_sleep(m, "tmfsmr");
goto lookupvpg;
+ }
vm_page_busy(m);
VM_OBJECT_UNLOCK(vobj);
error = uiomove_fromphys(&m, offset, tlen, uio);
@@ -526,8 +534,16 @@ lookupvpg:
VM_OBJECT_UNLOCK(vobj);
return (error);
} else if (m != NULL && uio->uio_segflg == UIO_NOCOPY) {
- if (vm_page_sleep_if_busy(m, FALSE, "tmfsmr"))
+ if ((m->oflags & VPO_BUSY) != 0) {
+ /*
+ * Reference the page before unlocking and sleeping so
+ * that the page daemon is less likely to reclaim it.
+ */
+ vm_page_lock_queues();
+ vm_page_flag_set(m, PG_REFERENCED);
+ vm_page_sleep(m, "tmfsmr");
goto lookupvpg;
+ }
vm_page_busy(m);
VM_OBJECT_UNLOCK(vobj);
sched_pin();
@@ -627,8 +643,16 @@ tmpfs_mappedwrite(vm_object_t vobj, vm_object_t tobj, size_t len, struct uio *ui
lookupvpg:
if (((vpg = vm_page_lookup(vobj, idx)) != NULL) &&
vm_page_is_valid(vpg, offset, tlen)) {
- if (vm_page_sleep_if_busy(vpg, FALSE, "tmfsmw"))
+ if ((vpg->oflags & VPO_BUSY) != 0) {
+ /*
+ * Reference the page before unlocking and sleeping so
+ * that the page daemon is less likely to reclaim it.
+ */
+ vm_page_lock_queues();
+ vm_page_flag_set(vpg, PG_REFERENCED);
+ vm_page_sleep(vpg, "tmfsmw");
goto lookupvpg;
+ }
vm_page_busy(vpg);
vm_page_lock_queues();
vm_page_undirty(vpg);
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