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Add a vm_page_change_lock() helper, the common code to not relock page

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lock if both old and new pages use the same underlying lock.  Convert
existing places to use the helper instead of inlining it.  Use the
optimization in vm_object_page_remove().

Suggested and reviewed by:	alc, markj
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
This commit is contained in:
kib 2017-09-09 17:35:19 +00:00
parent fa1f526510
commit d27f2b11c2
3 changed files with 34 additions and 53 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

26
sys/vm/vm_object.c
View File

@ -1917,6 +1917,7 @@ vm_object_page_remove(vm_object_t object, vm_pindex_t start, vm_pindex_t end,
int options)
{
vm_page_t p, next;
struct mtx *mtx;
VM_OBJECT_ASSERT_WLOCKED(object);
KASSERT((object->flags & OBJ_UNMANAGED) == 0 ||
@ -1927,6 +1928,7 @@ vm_object_page_remove(vm_object_t object, vm_pindex_t start, vm_pindex_t end,
vm_object_pip_add(object, 1);
again:
p = vm_page_find_least(object, start);
mtx = NULL;
/*
* Here, the variable "p" is either (1) the page with the least pindex
@ -1943,7 +1945,7 @@ again:
* however, be invalidated if the option OBJPR_CLEANONLY is
* not specified.
*/
vm_page_lock(p);
vm_page_change_lock(p, &mtx);
if (vm_page_xbusied(p)) {
VM_OBJECT_WUNLOCK(object);
vm_page_busy_sleep(p, "vmopax", true);
@ -1957,7 +1959,7 @@ again:
p->valid = 0;
vm_page_undirty(p);
}
goto next;
continue;
}
if (vm_page_busied(p)) {
VM_OBJECT_WUNLOCK(object);
@ -1971,14 +1973,14 @@ again:
if ((options & OBJPR_NOTMAPPED) == 0)
pmap_remove_write(p);
if (p->dirty)
goto next;
continue;
}
if ((options & OBJPR_NOTMAPPED) == 0)
pmap_remove_all(p);
vm_page_free(p);
next:
vm_page_unlock(p);
}
if (mtx != NULL)
mtx_unlock(mtx);
vm_object_pip_wakeup(object);
}
@ -2001,7 +2003,7 @@ next:
void
vm_object_page_noreuse(vm_object_t object, vm_pindex_t start, vm_pindex_t end)
{
struct mtx *mtx, *new_mtx;
struct mtx *mtx;
vm_page_t p, next;
VM_OBJECT_ASSERT_LOCKED(object);
@ -2018,17 +2020,7 @@ vm_object_page_noreuse(vm_object_t object, vm_pindex_t start, vm_pindex_t end)
mtx = NULL;
for (; p != NULL && (p->pindex < end || end == 0); p = next) {
next = TAILQ_NEXT(p, listq);
/*
* Avoid releasing and reacquiring the same page lock.
*/
new_mtx = vm_page_lockptr(p);
if (mtx != new_mtx) {
if (mtx != NULL)
mtx_unlock(mtx);
mtx = new_mtx;
mtx_lock(mtx);
}
vm_page_change_lock(p, &mtx);
vm_page_deactivate_noreuse(p);
}
if (mtx != NULL)

60
sys/vm/vm_page.c
View File

@ -937,6 +937,23 @@ vm_page_flash(vm_page_t m)
wakeup(m);
}
/*
* Avoid releasing and reacquiring the same page lock.
*/
void
vm_page_change_lock(vm_page_t m, struct mtx **mtx)
{
struct mtx *mtx1;
mtx1 = vm_page_lockptr(m);
if (*mtx == mtx1)
return;
if (*mtx != NULL)
mtx_unlock(*mtx);
*mtx = mtx1;
mtx_lock(mtx1);
}
/*
* Keep page from being freed by the page daemon
* much of the same effect as wiring, except much lower
@ -970,20 +987,11 @@ vm_page_unhold(vm_page_t mem)
void
vm_page_unhold_pages(vm_page_t *ma, int count)
{
struct mtx *mtx, *new_mtx;
struct mtx *mtx;
mtx = NULL;
for (; count != 0; count--) {
/*
* Avoid releasing and reacquiring the same page lock.
*/
new_mtx = vm_page_lockptr(*ma);
if (mtx != new_mtx) {
if (mtx != NULL)
mtx_unlock(mtx);
mtx = new_mtx;
mtx_lock(mtx);
}
vm_page_change_lock(*ma, &mtx);
vm_page_unhold(*ma);
ma++;
}
@ -2023,7 +2031,7 @@ vm_page_t
vm_page_scan_contig(u_long npages, vm_page_t m_start, vm_page_t m_end,
u_long alignment, vm_paddr_t boundary, int options)
{
struct mtx *m_mtx, *new_mtx;
struct mtx *m_mtx;
vm_object_t object;
vm_paddr_t pa;
vm_page_t m, m_run;
@ -2066,16 +2074,7 @@ vm_page_scan_contig(u_long npages, vm_page_t m_start, vm_page_t m_end,
} else
KASSERT(m_run != NULL, ("m_run == NULL"));
/*
* Avoid releasing and reacquiring the same page lock.
*/
new_mtx = vm_page_lockptr(m);
if (m_mtx != new_mtx) {
if (m_mtx != NULL)
mtx_unlock(m_mtx);
m_mtx = new_mtx;
mtx_lock(m_mtx);
}
vm_page_change_lock(m, &m_mtx);
m_inc = 1;
retry:
if (m->wire_count != 0 || m->hold_count != 0)
@ -2225,7 +2224,7 @@ static int
vm_page_reclaim_run(int req_class, u_long npages, vm_page_t m_run,
vm_paddr_t high)
{
struct mtx *m_mtx, *new_mtx;
struct mtx *m_mtx;
struct spglist free;
vm_object_t object;
vm_paddr_t pa;
@ -2246,13 +2245,7 @@ vm_page_reclaim_run(int req_class, u_long npages, vm_page_t m_run,
/*
* Avoid releasing and reacquiring the same page lock.
*/
new_mtx = vm_page_lockptr(m);
if (m_mtx != new_mtx) {
if (m_mtx != NULL)
mtx_unlock(m_mtx);
m_mtx = new_mtx;
mtx_lock(m_mtx);
}
vm_page_change_lock(m, &m_mtx);
retry:
if (m->wire_count != 0 || m->hold_count != 0)
error = EBUSY;
@ -2365,12 +2358,7 @@ retry:
* The new page must be deactivated
* before the object is unlocked.
*/
new_mtx = vm_page_lockptr(m_new);
if (m_mtx != new_mtx) {
mtx_unlock(m_mtx);
m_mtx = new_mtx;
mtx_lock(m_mtx);
}
vm_page_change_lock(m_new, &m_mtx);
vm_page_deactivate(m_new);
} else {
m->flags &= ~PG_ZERO;

1
sys/vm/vm_page.h
View File

@ -470,6 +470,7 @@ vm_page_t vm_page_alloc_contig(vm_object_t object, vm_pindex_t pindex, int req,
u_long npages, vm_paddr_t low, vm_paddr_t high, u_long alignment,
vm_paddr_t boundary, vm_memattr_t memattr);
vm_page_t vm_page_alloc_freelist(int, int);
void vm_page_change_lock(vm_page_t m, struct mtx **mtx);
vm_page_t vm_page_grab (vm_object_t, vm_pindex_t, int);
int vm_page_grab_pages(vm_object_t object, vm_pindex_t pindex, int allocflags,
vm_page_t *ma, int count);