diff options
| -rw-r--r-- | sys/i386/i386/pmap.c | 121 |
1 files changed, 69 insertions, 52 deletions
diff --git a/sys/i386/i386/pmap.c b/sys/i386/i386/pmap.c index f09abee..a3b93a7 100644 --- a/sys/i386/i386/pmap.c +++ b/sys/i386/i386/pmap.c @@ -2639,8 +2639,8 @@ pmap_demote_pde(pmap_t pmap, pd_entry_t *pde, vm_offset_t va) oldpde = *pde; KASSERT((oldpde & (PG_PS | PG_V)) == (PG_PS | PG_V), ("pmap_demote_pde: oldpde is missing PG_PS and/or PG_V")); - mpte = pmap_lookup_pt_page(pmap, va); - if (mpte != NULL) + if ((oldpde & PG_A) != 0 && (mpte = pmap_lookup_pt_page(pmap, va)) != + NULL) pmap_remove_pt_page(pmap, mpte); else { KASSERT((oldpde & PG_W) == 0, @@ -4744,6 +4744,8 @@ retry: rw_wunlock(&pvh_global_lock); } +#define PMAP_TS_REFERENCED_MAX 5 + /* * pmap_ts_referenced: * @@ -4760,73 +4762,88 @@ int pmap_ts_referenced(vm_page_t m) { struct md_page *pvh; - pv_entry_t pv, pvf, pvn; + pv_entry_t pv, pvf; pmap_t pmap; - pd_entry_t oldpde, *pde; + pd_entry_t *pde; pt_entry_t *pte; - vm_offset_t va; + vm_paddr_t pa; int rtval = 0; KASSERT((m->oflags & VPO_UNMANAGED) == 0, ("pmap_ts_referenced: page %p is not managed", m)); - pvh = pa_to_pvh(VM_PAGE_TO_PHYS(m)); + pa = VM_PAGE_TO_PHYS(m); + pvh = pa_to_pvh(pa); rw_wlock(&pvh_global_lock); sched_pin(); - if ((m->flags & PG_FICTITIOUS) != 0) + if ((m->flags & PG_FICTITIOUS) != 0 || + (pvf = TAILQ_FIRST(&pvh->pv_list)) == NULL) goto small_mappings; - TAILQ_FOREACH_SAFE(pv, &pvh->pv_list, pv_next, pvn) { - va = pv->pv_va; + pv = pvf; + do { pmap = PV_PMAP(pv); PMAP_LOCK(pmap); - pde = pmap_pde(pmap, va); - oldpde = *pde; - if ((oldpde & PG_A) != 0) { - if (pmap_demote_pde(pmap, pde, va)) { - if ((oldpde & PG_W) == 0) { - /* - * Remove the mapping to a single page - * so that a subsequent access may - * repromote. Since the underlying - * page table page is fully populated, - * this removal never frees a page - * table page. - */ - va += VM_PAGE_TO_PHYS(m) - (oldpde & - PG_PS_FRAME); - pmap_remove_page(pmap, va, NULL); - rtval++; - if (rtval > 4) { - PMAP_UNLOCK(pmap); - goto out; - } - } + pde = pmap_pde(pmap, pv->pv_va); + if ((*pde & PG_A) != 0) { + /* + * Since this reference bit is shared by either 1024 + * or 512 4KB pages, it should not be cleared every + * time it is tested. Apply a simple "hash" function + * on the physical page number, the virtual superpage + * number, and the pmap address to select one 4KB page + * out of the 1024 or 512 on which testing the + * reference bit will result in clearing that bit. + * This function is designed to avoid the selection of + * the same 4KB page for every 2- or 4MB page mapping. + * + * On demotion, a mapping that hasn't been referenced + * is simply destroyed. To avoid the possibility of a + * subsequent page fault on a demoted wired mapping, + * always leave its reference bit set. Moreover, + * since the superpage is wired, the current state of + * its reference bit won't affect page replacement. + */ + if ((((pa >> PAGE_SHIFT) ^ (pv->pv_va >> PDRSHIFT) ^ + (uintptr_t)pmap) & (NPTEPG - 1)) == 0 && + (*pde & PG_W) == 0) { + atomic_clear_int((u_int *)pde, PG_A); + pmap_invalidate_page(pmap, pv->pv_va); } + rtval++; } PMAP_UNLOCK(pmap); - } + /* Rotate the PV list if it has more than one entry. */ + if (TAILQ_NEXT(pv, pv_next) != NULL) { + TAILQ_REMOVE(&pvh->pv_list, pv, pv_next); + TAILQ_INSERT_TAIL(&pvh->pv_list, pv, pv_next); + } + if (rtval >= PMAP_TS_REFERENCED_MAX) + goto out; + } while ((pv = TAILQ_FIRST(&pvh->pv_list)) != pvf); small_mappings: - if ((pv = TAILQ_FIRST(&m->md.pv_list)) != NULL) { - pvf = pv; - do { - pvn = TAILQ_NEXT(pv, pv_next); + if ((pvf = TAILQ_FIRST(&m->md.pv_list)) == NULL) + goto out; + pv = pvf; + do { + pmap = PV_PMAP(pv); + PMAP_LOCK(pmap); + pde = pmap_pde(pmap, pv->pv_va); + KASSERT((*pde & PG_PS) == 0, + ("pmap_ts_referenced: found a 4mpage in page %p's pv list", + m)); + pte = pmap_pte_quick(pmap, pv->pv_va); + if ((*pte & PG_A) != 0) { + atomic_clear_int((u_int *)pte, PG_A); + pmap_invalidate_page(pmap, pv->pv_va); + rtval++; + } + PMAP_UNLOCK(pmap); + /* Rotate the PV list if it has more than one entry. */ + if (TAILQ_NEXT(pv, pv_next) != NULL) { TAILQ_REMOVE(&m->md.pv_list, pv, pv_next); TAILQ_INSERT_TAIL(&m->md.pv_list, pv, pv_next); - pmap = PV_PMAP(pv); - PMAP_LOCK(pmap); - pde = pmap_pde(pmap, pv->pv_va); - KASSERT((*pde & PG_PS) == 0, ("pmap_ts_referenced:" - " found a 4mpage in page %p's pv list", m)); - pte = pmap_pte_quick(pmap, pv->pv_va); - if ((*pte & PG_A) != 0) { - atomic_clear_int((u_int *)pte, PG_A); - pmap_invalidate_page(pmap, pv->pv_va); - rtval++; - if (rtval > 4) - pvn = NULL; - } - PMAP_UNLOCK(pmap); - } while ((pv = pvn) != NULL && pv != pvf); - } + } + } while ((pv = TAILQ_FIRST(&m->md.pv_list)) != pvf && rtval < + PMAP_TS_REFERENCED_MAX); out: sched_unpin(); rw_wunlock(&pvh_global_lock); |
