Author: alc
Date: Fri Jul 2 19:59:18 2010
New Revision: 209650
URL: http://svn.freebsd.org/changeset/base/209650
Log:
Use vm_page_prev() instead of vm_page_lookup() in the implementation of
vm_fault()'s automatic delete-behind heuristic.
vm_page_prev() is typically faster.
Modified:
head/sys/vm/vm_fault.c
Modified: head/sys/vm/vm_fault.c
==============================================================================
--- head/sys/vm/vm_fault.c Fri Jul 2 17:22:15 2010 (r209649)
+++ head/sys/vm/vm_fault.c Fri Jul 2 19:59:18 2010 (r209650)
@@ -214,7 +214,7 @@ vm_fault(vm_map_t map, vm_offset_t vaddr
boolean_t growstack, wired;
int map_generation;
vm_object_t next_object;
- vm_page_t marray[VM_FAULT_READ];
+ vm_page_t marray[VM_FAULT_READ], mt, mt_prev;
int hardfault;
int faultcount, ahead, behind, alloc_req;
struct faultstate fs;
@@ -465,26 +465,28 @@ readrest:
fs.first_object->type != OBJT_DEVICE &&
fs.first_object->type != OBJT_PHYS &&
fs.first_object->type != OBJT_SG) {
- vm_pindex_t firstpindex, tmppindex;
+ vm_pindex_t firstpindex;
if (fs.first_pindex < 2 * VM_FAULT_READ)
firstpindex = 0;
else
firstpindex = fs.first_pindex - 2 *
VM_FAULT_READ;
+ mt = fs.first_object != fs.object ?
+ fs.first_m : fs.m;
+ KASSERT(mt != NULL, ("vm_fault: missing mt"));
+ KASSERT((mt->oflags & VPO_BUSY) != 0,
+ ("vm_fault: mt %p not busy", mt));
+ mt_prev = vm_page_prev(mt);
/*
* note: partially valid pages cannot be
* included in the lookahead - NFS piecemeal
* writes will barf on it badly.
*/
- for (tmppindex = fs.first_pindex - 1;
- tmppindex >= firstpindex;
- --tmppindex) {
- vm_page_t mt;
-
- mt = vm_page_lookup(fs.first_object,
tmppindex);
- if (mt == NULL || (mt->valid !=
VM_PAGE_BITS_ALL))
- break;
+ while ((mt = mt_prev) != NULL &&
+ mt->pindex >= firstpindex &&
+ mt->valid == VM_PAGE_BITS_ALL) {
+ mt_prev = vm_page_prev(mt);
if (mt->busy ||
(mt->oflags & VPO_BUSY))
continue;
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