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vm_page_replace: remove redundant radix lookup

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Remove redundant lookup of the old page from vm_page_replace.  Verification
that the old page exists is already done by vm_radix_replace.

Submitted by:	Ryan Libby <rlibby@gmail.com>
Reviewed by:	alc, kib
Sponsored by:	EMC / Isilon Storage Division
Follow-up to:	https://reviews.freebsd.org/D4326
Differential Revision:	https://reviews.freebsd.org/D4471
This commit is contained in:
Conrad Meyer 2015-12-10 22:57:27 +00:00
parent 62ac7dd2bf
commit 5e09bdc821
1 changed files with 9 additions and 14 deletions
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23
sys/vm/vm_page.c
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@ -1324,22 +1324,17 @@ vm_page_prev(vm_page_t m)
vm_page_t
vm_page_replace(vm_page_t mnew, vm_object_t object, vm_pindex_t pindex)
{
vm_page_t mold, mpred;
vm_page_t mold;
VM_OBJECT_ASSERT_WLOCKED(object);
KASSERT(mnew->object == NULL,
("vm_page_replace: page already in object"));
/*
* This function mostly follows vm_page_insert() and
* vm_page_remove() without the radix, object count and vnode
* dance. Double check such functions for more comments.
*/
mpred = vm_radix_lookup(&object->rtree, pindex);
KASSERT(mpred != NULL,
("vm_page_replace: replacing page not present with pindex"));
mpred = TAILQ_PREV(mpred, respgs, listq);
if (mpred != NULL)
KASSERT(mpred->pindex < pindex,
("vm_page_insert_after: mpred doesn't precede pindex"));
mnew->object = object;
mnew->pindex = pindex;
@ -1347,17 +1342,17 @@ vm_page_replace(vm_page_t mnew, vm_object_t object, vm_pindex_t pindex)
KASSERT(mold->queue == PQ_NONE,
("vm_page_replace: mold is on a paging queue"));
/* Detach the old page from the resident tailq. */
/* Keep the resident page list in sorted order. */
TAILQ_INSERT_AFTER(&object->memq, mold, mnew, listq);
TAILQ_REMOVE(&object->memq, mold, listq);
mold->object = NULL;
vm_page_xunbusy(mold);
/* Insert the new page in the resident tailq. */
if (mpred != NULL)
TAILQ_INSERT_AFTER(&object->memq, mpred, mnew, listq);
else
TAILQ_INSERT_HEAD(&object->memq, mnew, listq);
/*
* The object's resident_page_count does not change because we have
* swapped one page for another, but OBJ_MIGHTBEDIRTY.
*/
if (pmap_page_is_write_mapped(mnew))
vm_object_set_writeable_dirty(object);
return (mold);