Author: kib
Date: Mon Jul 5 21:13:32 2010
New Revision: 209713
URL: http://svn.freebsd.org/changeset/base/209713
Log:
Add the ability for the allocflag argument of the vm_page_grab() to
specify the increment of vm_pageout_deficit when sleeping due to page
shortage. Then, in allocbuf(), the code to allocate pages when extending
vmio buffer can be replaced by a call to vm_page_grab().
Suggested and reviewed by: alc
MFC after: 2 weeks
Modified:
head/sys/kern/vfs_bio.c
head/sys/vm/vm_page.c
head/sys/vm/vm_page.h
Modified: head/sys/kern/vfs_bio.c
==============================================================================
--- head/sys/kern/vfs_bio.c Mon Jul 5 19:01:10 2010 (r209712)
+++ head/sys/kern/vfs_bio.c Mon Jul 5 21:13:32 2010 (r209713)
@@ -3013,63 +3013,24 @@ allocbuf(struct buf *bp, int size)
VM_OBJECT_LOCK(obj);
while (bp->b_npages < desiredpages) {
vm_page_t m;
- vm_pindex_t pi;
-
- pi = OFF_TO_IDX(bp->b_offset) + bp->b_npages;
- if ((m = vm_page_lookup(obj, pi)) == NULL) {
- /*
- * note: must allocate system pages
- * since blocking here could intefere
- * with paging I/O, no matter which
- * process we are.
- */
- m = vm_page_alloc(obj, pi,
- VM_ALLOC_NOBUSY | VM_ALLOC_SYSTEM |
- VM_ALLOC_WIRED);
- if (m == NULL) {
-
atomic_add_int(&vm_pageout_deficit,
- desiredpages -
bp->b_npages);
- VM_OBJECT_UNLOCK(obj);
- VM_WAIT;
- VM_OBJECT_LOCK(obj);
- } else {
- if (m->valid == 0)
- bp->b_flags &= ~B_CACHE;
- bp->b_pages[bp->b_npages] = m;
- ++bp->b_npages;
- }
- continue;
- }
/*
- * We found a page. If we have to sleep on it,
- * retry because it might have gotten freed out
- * from under us.
+ * We must allocate system pages since blocking
+ * here could intefere with paging I/O, no
+ * matter which process we are.
*
* We can only test VPO_BUSY here. Blocking on
* m->busy might lead to a deadlock:
- *
* vm_fault->getpages->cluster_read->allocbuf
- *
- */
- 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, "pgtblk");
- continue;
- }
-
- /*
- * We have a good page.
+ * Thus, we specify VM_ALLOC_IGN_SBUSY.
*/
- vm_page_lock(m);
- vm_page_wire(m);
- vm_page_unlock(m);
+ m = vm_page_grab(obj, OFF_TO_IDX(bp->b_offset) +
+ bp->b_npages, VM_ALLOC_NOBUSY |
+ VM_ALLOC_SYSTEM | VM_ALLOC_WIRED |
+ VM_ALLOC_RETRY | VM_ALLOC_IGN_SBUSY |
+ VM_ALLOC_COUNT(desiredpages -
bp->b_npages));
+ if (m->valid == 0)
+ bp->b_flags &= ~B_CACHE;
bp->b_pages[bp->b_npages] = m;
++bp->b_npages;
}
Modified: head/sys/vm/vm_page.c
==============================================================================
--- head/sys/vm/vm_page.c Mon Jul 5 19:01:10 2010 (r209712)
+++ head/sys/vm/vm_page.c Mon Jul 5 21:13:32 2010 (r209713)
@@ -2038,11 +2038,13 @@ vm_page_t
vm_page_grab(vm_object_t object, vm_pindex_t pindex, int allocflags)
{
vm_page_t m;
+ u_int count;
VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
retrylookup:
if ((m = vm_page_lookup(object, pindex)) != NULL) {
- if ((m->oflags & VPO_BUSY) != 0 || m->busy != 0) {
+ if ((m->oflags & VPO_BUSY) != 0 ||
+ ((allocflags & VM_ALLOC_IGN_SBUSY) == 0 && m->busy != 0)) {
if ((allocflags & VM_ALLOC_RETRY) != 0) {
/*
* Reference the page before unlocking and
@@ -2067,9 +2069,13 @@ retrylookup:
return (m);
}
}
- m = vm_page_alloc(object, pindex, allocflags & ~VM_ALLOC_RETRY);
+ m = vm_page_alloc(object, pindex, allocflags & ~(VM_ALLOC_RETRY |
+ VM_ALLOC_IGN_SBUSY | VM_ALLOC_COUNT_MASK));
if (m == NULL) {
VM_OBJECT_UNLOCK(object);
+ count = (u_int)allocflags >> VM_ALLOC_COUNT_SHIFT;
+ if (count > 0)
+ atomic_add_int(&vm_pageout_deficit, count);
VM_WAIT;
VM_OBJECT_LOCK(object);
if ((allocflags & VM_ALLOC_RETRY) == 0)
Modified: head/sys/vm/vm_page.h
==============================================================================
--- head/sys/vm/vm_page.h Mon Jul 5 19:01:10 2010 (r209712)
+++ head/sys/vm/vm_page.h Mon Jul 5 21:13:32 2010 (r209713)
@@ -317,6 +317,11 @@ extern struct vpglocks vm_page_queue_loc
#define VM_ALLOC_NOBUSY 0x0200 /* Do not busy the page */
#define VM_ALLOC_IFCACHED 0x0400 /* Fail if the page is not
cached */
#define VM_ALLOC_IFNOTCACHED 0x0800 /* Fail if the page is cached */
+#define VM_ALLOC_IGN_SBUSY 0x1000 /* vm_page_grab() only */
+
+#define VM_ALLOC_COUNT_SHIFT 16
+#define VM_ALLOC_COUNT(count) ((count) << VM_ALLOC_COUNT_SHIFT)
+#define VM_ALLOC_COUNT_MASK VM_ALLOC_COUNT(0xffff)
void vm_page_flag_set(vm_page_t m, unsigned short bits);
void vm_page_flag_clear(vm_page_t m, unsigned short bits);
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