Author: alc
Date: Mon Jun 10 01:48:21 2013
New Revision: 251591
URL: http://svnweb.freebsd.org/changeset/base/251591
Log:
Revise the interface between vm_object_madvise() and vm_page_dontneed() so
that pointless calls to pmap_is_modified() can be easily avoided when
performing madvise(..., MADV_FREE).
Sponsored by: EMC / Isilon Storage Division
Modified:
head/sys/vm/vm_object.c
head/sys/vm/vm_page.c
head/sys/vm/vm_page.h
Modified: head/sys/vm/vm_object.c
==============================================================================
--- head/sys/vm/vm_object.c Sun Jun 9 23:51:26 2013 (r251590)
+++ head/sys/vm/vm_object.c Mon Jun 10 01:48:21 2013 (r251591)
@@ -1175,28 +1175,8 @@ shadowlookup:
}
if (advise == MADV_WILLNEED) {
vm_page_activate(m);
- } else if (advise == MADV_DONTNEED) {
- vm_page_dontneed(m);
- } else if (advise == MADV_FREE) {
- /*
- * Mark the page clean. This will allow the page
- * to be freed up by the system. However, such pages
- * are often reused quickly by malloc()/free()
- * so we do not do anything that would cause
- * a page fault if we can help it.
- *
- * Specifically, we do not try to actually free
- * the page now nor do we try to put it in the
- * cache (which would cause a page fault on reuse).
- *
- * But we do make the page is freeable as we
- * can without actually taking the step of unmapping
- * it.
- */
- pmap_clear_modify(m);
- m->dirty = 0;
- m->act_count = 0;
- vm_page_dontneed(m);
+ } else {
+ vm_page_advise(m, advise);
}
vm_page_unlock(m);
if (advise == MADV_FREE && tobject->type == OBJT_SWAP)
Modified: head/sys/vm/vm_page.c
==============================================================================
--- head/sys/vm/vm_page.c Sun Jun 9 23:51:26 2013 (r251590)
+++ head/sys/vm/vm_page.c Mon Jun 10 01:48:21 2013 (r251591)
@@ -93,6 +93,7 @@ __FBSDID("$FreeBSD$");
#include <sys/kernel.h>
#include <sys/limits.h>
#include <sys/malloc.h>
+#include <sys/mman.h>
#include <sys/msgbuf.h>
#include <sys/mutex.h>
#include <sys/proc.h>
@@ -2238,15 +2239,15 @@ vm_page_cache(vm_page_t m)
}
/*
- * vm_page_dontneed
+ * vm_page_advise
*
* Cache, deactivate, or do nothing as appropriate. This routine
- * is typically used by madvise() MADV_DONTNEED.
+ * is used by madvise().
*
* Generally speaking we want to move the page into the cache so
* it gets reused quickly. However, this can result in a silly syndrome
* due to the page recycling too quickly. Small objects will not be
- * fully cached. On the otherhand, if we move the page to the inactive
+ * fully cached. On the other hand, if we move the page to the inactive
* queue we wind up with a problem whereby very large objects
* unnecessarily blow away our inactive and cache queues.
*
@@ -2261,13 +2262,31 @@ vm_page_cache(vm_page_t m)
* The object and page must be locked.
*/
void
-vm_page_dontneed(vm_page_t m)
+vm_page_advise(vm_page_t m, int advice)
{
- int dnw;
- int head;
+ int dnw, head;
- vm_page_lock_assert(m, MA_OWNED);
+ vm_page_assert_locked(m);
VM_OBJECT_ASSERT_WLOCKED(m->object);
+ if (advice == MADV_FREE) {
+ /*
+ * Mark the page clean. This will allow the page to be freed
+ * up by the system. However, such pages are often reused
+ * quickly by malloc() so we do not do anything that would
+ * cause a page fault if we can help it.
+ *
+ * Specifically, we do not try to actually free the page now
+ * nor do we try to put it in the cache (which would cause a
+ * page fault on reuse).
+ *
+ * But we do make the page is freeable as we can without
+ * actually taking the step of unmapping it.
+ */
+ pmap_clear_modify(m);
+ m->dirty = 0;
+ m->act_count = 0;
+ } else if (advice != MADV_DONTNEED)
+ return;
dnw = PCPU_GET(dnweight);
PCPU_INC(dnweight);
@@ -2294,7 +2313,7 @@ vm_page_dontneed(vm_page_t m)
pmap_clear_reference(m);
vm_page_aflag_clear(m, PGA_REFERENCED);
- if (m->dirty == 0 && pmap_is_modified(m))
+ if (advice != MADV_FREE && m->dirty == 0 && pmap_is_modified(m))
vm_page_dirty(m);
if (m->dirty || (dnw & 0x0070) == 0) {
Modified: head/sys/vm/vm_page.h
==============================================================================
--- head/sys/vm/vm_page.h Sun Jun 9 23:51:26 2013 (r251590)
+++ head/sys/vm/vm_page.h Mon Jun 10 01:48:21 2013 (r251591)
@@ -370,6 +370,7 @@ void vm_page_free_zero(vm_page_t m);
void vm_page_wakeup(vm_page_t m);
void vm_page_activate (vm_page_t);
+void vm_page_advise(vm_page_t m, int advice);
vm_page_t vm_page_alloc (vm_object_t, vm_pindex_t, int);
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,
@@ -381,7 +382,6 @@ void vm_page_cache_free(vm_object_t, vm_
void vm_page_cache_transfer(vm_object_t, vm_pindex_t, vm_object_t);
int vm_page_try_to_cache (vm_page_t);
int vm_page_try_to_free (vm_page_t);
-void vm_page_dontneed(vm_page_t);
void vm_page_deactivate (vm_page_t);
void vm_page_dequeue(vm_page_t m);
void vm_page_dequeue_locked(vm_page_t m);
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