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Optimize pmap_pv_demote_pde().

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This commit is contained in:
Alan Cox 2012-06-28 05:42:04 +00:00
parent be4aa869c1
commit 23e59dfa8d
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=237684
1 changed files with 35 additions and 10 deletions
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45
sys/amd64/amd64/pmap.c
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@ -2469,11 +2469,14 @@ pmap_pv_demote_pde(pmap_t pmap, vm_offset_t va, vm_paddr_t pa,
struct rwlock **lockp)
{
struct md_page *pvh;
struct pv_chunk *pc;
pv_entry_t pv;
vm_offset_t va_last;
vm_page_t m;
int bit, field;
rw_assert(&pvh_global_lock, RA_LOCKED);
PMAP_LOCK_ASSERT(pmap, MA_OWNED);
KASSERT((pa & PDRMASK) == 0,
("pmap_pv_demote_pde: pa is not 2mpage aligned"));
reserve_pv_entries(pmap, NPTEPG - 1, lockp);
@ -2481,7 +2484,8 @@ pmap_pv_demote_pde(pmap_t pmap, vm_offset_t va, vm_paddr_t pa,
/*
* Transfer the 2mpage's pv entry for this mapping to the first
* page's pv list.
* page's pv list. Once this transfer begins, the pv list lock
* must not be released until the last pv entry is reinstantiated.
*/
pvh = pa_to_pvh(pa);
va = trunc_2mpage(va);
@ -2490,16 +2494,37 @@ pmap_pv_demote_pde(pmap_t pmap, vm_offset_t va, vm_paddr_t pa,
m = PHYS_TO_VM_PAGE(pa);
TAILQ_INSERT_TAIL(&m->md.pv_list, pv, pv_list);
/* Instantiate the remaining NPTEPG - 1 pv entries. */
PV_STAT(atomic_add_long(&pv_entry_allocs, NPTEPG - 1));
va_last = va + NBPDR - PAGE_SIZE;
do {
m++;
KASSERT((m->oflags & VPO_UNMANAGED) == 0,
("pmap_pv_demote_pde: page %p is not managed", m));
va += PAGE_SIZE;
pv = get_pv_entry(pmap, TRUE);
pv->pv_va = va;
TAILQ_INSERT_TAIL(&m->md.pv_list, pv, pv_list);
} while (va < va_last);
for (;;) {
pc = TAILQ_FIRST(&pmap->pm_pvchunk);
KASSERT(pc->pc_map[0] != 0 || pc->pc_map[1] != 0 ||
pc->pc_map[2] != 0, ("pmap_pv_demote_pde: missing spare"));
for (field = 0; field < _NPCM; field++) {
while (pc->pc_map[field]) {
bit = bsfq(pc->pc_map[field]);
pc->pc_map[field] &= ~(1ul << bit);
pv = &pc->pc_pventry[field * 64 + bit];
va += PAGE_SIZE;
pv->pv_va = va;
m++;
KASSERT((m->oflags & VPO_UNMANAGED) == 0,
("pmap_pv_demote_pde: page %p is not managed", m));
TAILQ_INSERT_TAIL(&m->md.pv_list, pv, pv_list);
if (va == va_last)
goto out;
}
}
TAILQ_REMOVE(&pmap->pm_pvchunk, pc, pc_list);
TAILQ_INSERT_TAIL(&pmap->pm_pvchunk, pc, pc_list);
}
out:
if (pc->pc_map[0] == 0 && pc->pc_map[1] == 0 && pc->pc_map[2] == 0) {
TAILQ_REMOVE(&pmap->pm_pvchunk, pc, pc_list);
TAILQ_INSERT_TAIL(&pmap->pm_pvchunk, pc, pc_list);
}
PV_STAT(atomic_add_long(&pv_entry_count, NPTEPG - 1));
PV_STAT(atomic_subtract_int(&pv_entry_spare, NPTEPG - 1));
}
/*