Author: alc
Date: Mon Feb 9 06:23:21 2009
New Revision: 188383
URL: http://svn.freebsd.org/changeset/base/188383
Log:
Avoid some cases of unnecessary page queues locking by vm_fault's delete-
behind heuristic.
Modified:
head/sys/vm/vm_fault.c
Modified: head/sys/vm/vm_fault.c
==============================================================================
--- head/sys/vm/vm_fault.c Mon Feb 9 05:09:52 2009 (r188382)
+++ head/sys/vm/vm_fault.c Mon Feb 9 06:23:21 2009 (r188383)
@@ -212,7 +212,7 @@ vm_fault(vm_map_t map, vm_offset_t vaddr
{
vm_prot_t prot;
int is_first_object_locked, result;
- boolean_t growstack, wired;
+ boolean_t are_queues_locked, growstack, wired;
int map_generation;
vm_object_t next_object;
vm_page_t marray[VM_FAULT_READ];
@@ -480,7 +480,7 @@ readrest:
else
firstpindex = fs.first_pindex - 2 *
VM_FAULT_READ;
- vm_page_lock_queues();
+ are_queues_locked = FALSE;
/*
* note: partially valid pages cannot be
* included in the lookahead - NFS piecemeal
@@ -495,8 +495,13 @@ readrest:
if (mt == NULL || (mt->valid !=
VM_PAGE_BITS_ALL))
break;
if (mt->busy ||
- (mt->oflags & VPO_BUSY) ||
- mt->hold_count ||
+ (mt->oflags & VPO_BUSY))
+ continue;
+ if (!are_queues_locked) {
+ are_queues_locked = TRUE;
+ vm_page_lock_queues();
+ }
+ if (mt->hold_count ||
mt->wire_count)
continue;
pmap_remove_all(mt);
@@ -506,7 +511,8 @@ readrest:
vm_page_cache(mt);
}
}
- vm_page_unlock_queues();
+ if (are_queues_locked)
+ vm_page_unlock_queues();
ahead += behind;
behind = 0;
}
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