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Use vm_page_prev() instead of vm_page_lookup() in the implementation of

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vm_fault()'s automatic delete-behind heuristic.
vm_page_prev() is typically faster.
This commit is contained in:
Alan Cox 2010-07-02 19:59:18 +00:00
parent af565edaaa
commit 4b0640310a
1 changed files with 12 additions and 10 deletions
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22
sys/vm/vm_fault.c
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@ -214,7 +214,7 @@ vm_fault(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type,
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 @@ RetryFault:;
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;