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With the changes over the past year to how accesses to the page's dirty

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field are synchronized, there is no need for pmap_protect() to acquire
the page queues lock unless it is going to access the pv lists.

Reviewed by:	kib
This commit is contained in:
alc 2012-03-17 22:04:58 +00:00
parent 26b44e3c9d
commit eb494d678d
1 changed files with 24 additions and 5 deletions
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29
sys/amd64/amd64/pmap.c
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@ -2940,6 +2940,7 @@ pmap_protect(pmap_t pmap, vm_offset_t sva, vm_offset_t eva, vm_prot_t prot)
pd_entry_t ptpaddr, *pde;
pt_entry_t *pte;
int anychanged;
boolean_t pv_lists_locked;
if ((prot & VM_PROT_READ) == VM_PROT_NONE) {
pmap_remove(pmap, sva, eva);
@ -2950,9 +2951,10 @@ pmap_protect(pmap_t pmap, vm_offset_t sva, vm_offset_t eva, vm_prot_t prot)
(VM_PROT_WRITE|VM_PROT_EXECUTE))
return;
pv_lists_locked = FALSE;
resume:
anychanged = 0;
vm_page_lock_queues();
PMAP_LOCK(pmap);
for (; sva < eva; sva = va_next) {
@ -3001,9 +3003,25 @@ pmap_protect(pmap_t pmap, vm_offset_t sva, vm_offset_t eva, vm_prot_t prot)
if (pmap_protect_pde(pmap, pde, sva, prot))
anychanged = 1;
continue;
} else if (!pmap_demote_pde(pmap, pde, sva)) {
/* The large page mapping was destroyed. */
continue;
} else {
if (!pv_lists_locked) {
pv_lists_locked = TRUE;
if (!mtx_trylock(&vm_page_queue_mtx)) {
if (anychanged)
pmap_invalidate_all(
pmap);
PMAP_UNLOCK(pmap);
vm_page_lock_queues();
goto resume;
}
}
if (!pmap_demote_pde(pmap, pde, sva)) {
/*
* The large page mapping was
* destroyed.
*/
continue;
}
}
}
@ -3043,7 +3061,8 @@ retry:
}
if (anychanged)
pmap_invalidate_all(pmap);
vm_page_unlock_queues();
if (pv_lists_locked)
vm_page_unlock_queues();
PMAP_UNLOCK(pmap);
}