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Avoid some cases of unnecessary page queues locking by vm_fault's delete-

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behind heuristic.
This commit is contained in:
Alan Cox 2009-02-09 06:23:21 +00:00
parent d66a21e9f2
commit c722e407dc
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=188383
1 changed files with 11 additions and 5 deletions
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16
sys/vm/vm_fault.c
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@ -212,7 +212,7 @@ vm_fault(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type,
{
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 @@ RetryFault:;
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 @@ RetryFault:;
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 @@ RetryFault:;
vm_page_cache(mt);
}
}
vm_page_unlock_queues();
if (are_queues_locked)
vm_page_unlock_queues();
ahead += behind;
behind = 0;
}