Simplify the implementation of pmap_emulate_reference(). The new version
simply manipulates the pte which faulted instead of traversing the mapping list for that page. This makes it possible to complete the trap without needing locks and incidentally improves the accuracy of some statistics used by the VM system.
This commit is contained in:
Doug Rabson
parent
5007eafa5e
commit
d4127edb9d
@ -1189,7 +1189,6 @@ pmap_pinit0(pmap)
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int i;
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pmap->pm_lev1 = Lev1map;
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pmap->pm_flags = 0;
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pmap->pm_count = 1;
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pmap->pm_ptphint = NULL;
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pmap->pm_active = 0;
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@ -1239,7 +1238,6 @@ pmap_pinit(pmap)
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pmap->pm_lev1[PTLEV1I] = pmap_phys_to_pte(VM_PAGE_TO_PHYS(lev1pg))
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| PG_V | PG_KRE | PG_KWE;
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pmap->pm_flags = 0;
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pmap->pm_count = 1;
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pmap->pm_ptphint = NULL;
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pmap->pm_active = 0;
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@ -2107,16 +2105,10 @@ validate:
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newpte = pmap_phys_to_pte(pa) | pte_prot(pmap, prot) | PG_V | managed;
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if (managed) {
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vm_page_t om;
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/*
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* Set up referenced/modified emulation for the new mapping
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*/
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om = PHYS_TO_VM_PAGE(pa);
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if ((om->md.pv_flags & PV_TABLE_REF) == 0)
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newpte |= PG_FOR | PG_FOW | PG_FOE;
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else if ((om->md.pv_flags & PV_TABLE_MOD) == 0)
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newpte |= PG_FOW;
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newpte |= origpte & (PG_FOR | PG_FOW | PG_FOE);
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}
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if (wired)
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@ -2745,16 +2737,32 @@ pmap_phys_address(ppn)
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int
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pmap_ts_referenced(vm_page_t m)
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{
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pv_entry_t pv;
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pt_entry_t *pte;
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int count;
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if (!pmap_initialized || (m->flags & PG_FICTITIOUS))
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return 0;
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if (m->md.pv_flags & PV_TABLE_REF) {
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pmap_changebit(m, PG_FOR|PG_FOE|PG_FOW, TRUE);
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m->md.pv_flags &= ~PV_TABLE_REF;
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return 1;
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/*
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* Loop over current mappings looking for any which have don't
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* have PG_FOR set (i.e. ones where we have taken an emulate
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* reference trap recently).
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*/
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count = 0;
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for (pv = TAILQ_FIRST(&m->md.pv_list);
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pv;
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pv = TAILQ_NEXT(pv, pv_list)) {
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pte = pmap_lev3pte(pv->pv_pmap, pv->pv_va);
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if (!(*pte & PG_FOR)) {
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count++;
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*pte |= PG_FOR | PG_FOE;
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pmap_invalidate_page(pv->pv_pmap, pv->pv_va);
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}
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}
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return 0;
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return count;
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}
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/*
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@ -2766,11 +2774,25 @@ pmap_ts_referenced(vm_page_t m)
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boolean_t
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pmap_is_modified(vm_page_t m)
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{
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pv_entry_t pv;
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pt_entry_t *pte;
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if (!pmap_initialized || (m->flags & PG_FICTITIOUS))
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return FALSE;
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return (m->md.pv_flags & PV_TABLE_MOD) != 0;
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/*
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* A page is modified if any mapping has had its PG_FOW flag
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* cleared.
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*/
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for (pv = TAILQ_FIRST(&m->md.pv_list);
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pv;
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pv = TAILQ_NEXT(pv, pv_list)) {
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pte = pmap_lev3pte(pv->pv_pmap, pv->pv_va);
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if (!(*pte & PG_FOW))
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return 1;
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}
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return 0;
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}
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/*
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@ -2779,12 +2801,24 @@ pmap_is_modified(vm_page_t m)
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void
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pmap_clear_modify(vm_page_t m)
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{
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pv_entry_t pv;
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pt_entry_t *pte;
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if (!pmap_initialized || (m->flags & PG_FICTITIOUS))
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return;
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if (m->md.pv_flags & PV_TABLE_MOD) {
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pmap_changebit(m, PG_FOW, TRUE);
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m->md.pv_flags &= ~PV_TABLE_MOD;
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/*
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* Loop over current mappings setting PG_FOW where needed.
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*/
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for (pv = TAILQ_FIRST(&m->md.pv_list);
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pv;
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pv = TAILQ_NEXT(pv, pv_list)) {
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pte = pmap_lev3pte(pv->pv_pmap, pv->pv_va);
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if (!(*pte & PG_FOW)) {
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*pte |= PG_FOW;
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pmap_invalidate_page(pv->pv_pmap, pv->pv_va);
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}
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}
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}
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@ -2809,12 +2843,24 @@ pmap_page_is_free(vm_page_t m)
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void
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pmap_clear_reference(vm_page_t m)
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{
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pv_entry_t pv;
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pt_entry_t *pte;
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if (!pmap_initialized || (m->flags & PG_FICTITIOUS))
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return;
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if (m->md.pv_flags & PV_TABLE_REF) {
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pmap_changebit(m, PG_FOR|PG_FOE|PG_FOW, TRUE);
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m->md.pv_flags &= ~PV_TABLE_REF;
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/*
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* Loop over current mappings setting PG_FOR and PG_FOE where needed.
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*/
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for (pv = TAILQ_FIRST(&m->md.pv_list);
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pv;
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pv = TAILQ_NEXT(pv, pv_list)) {
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pte = pmap_lev3pte(pv->pv_pmap, pv->pv_va);
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if (!(*pte & (PG_FOR | PG_FOE))) {
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*pte |= (PG_FOR | PG_FOE);
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pmap_invalidate_page(pv->pv_pmap, pv->pv_va);
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}
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}
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}
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@ -2829,7 +2875,6 @@ pmap_emulate_reference(struct proc *p, vm_offset_t v, int user, int write)
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{
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pt_entry_t faultoff, *pte;
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vm_offset_t pa;
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vm_page_t m;
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int user_addr;
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/*
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@ -2883,36 +2928,14 @@ pmap_emulate_reference(struct proc *p, vm_offset_t v, int user, int write)
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* (1) always mark page as used, and
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* (2) if it was a write fault, mark page as modified.
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*/
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m = PHYS_TO_VM_PAGE(pa);
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m->md.pv_flags |= PV_TABLE_REF;
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faultoff = PG_FOR | PG_FOE;
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if (user_addr) {
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mtx_lock(&Giant);
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vm_page_flag_set(m, PG_REFERENCED);
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mtx_unlock(&Giant);
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}
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if (write) {
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m->md.pv_flags |= PV_TABLE_MOD;
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vm_page_dirty(m);
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faultoff |= PG_FOW;
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}
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pmap_changebit(m, faultoff, FALSE);
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if ((*pte & faultoff) != 0) {
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#if 1
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/*
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* XXX dfr - don't think its possible in our pmap
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*/
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/*
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* This is apparently normal. Why? -- cgd
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* XXX because was being called on unmanaged pages?
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*/
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panic("warning: pmap_changebit didn't.");
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#endif
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*pte &= ~faultoff;
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ALPHA_TBIS(v);
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faultoff = PG_FOR | PG_FOE | PG_FOW;
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} else {
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faultoff = PG_FOR | PG_FOE;
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}
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*pte = (*pte & ~faultoff);
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ALPHA_TBIS(v);
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}
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/*
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@ -2975,7 +2998,6 @@ pmap_mincore(pmap, addr)
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pmap_t pmap;
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vm_offset_t addr;
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{
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pt_entry_t *pte;
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int val = 0;
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@ -2999,7 +3021,7 @@ pmap_mincore(pmap, addr)
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/*
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* Modified by us
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*/
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if (m->md.pv_flags & PV_TABLE_MOD)
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if ((*pte & PG_FOW) == 0)
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val |= MINCORE_MODIFIED|MINCORE_MODIFIED_OTHER;
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/*
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* Modified by someone
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@ -3009,7 +3031,7 @@ pmap_mincore(pmap, addr)
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/*
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* Referenced by us
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*/
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if (m->md.pv_flags & PV_TABLE_REF)
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if ((*pte & (PG_FOR | PG_FOE)) == 0)
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val |= MINCORE_REFERENCED|MINCORE_REFERENCED_OTHER;
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/*
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@ -434,11 +434,10 @@ trap(a0, a1, a2, entry, framep)
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case ALPHA_MMCSR_FOR:
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case ALPHA_MMCSR_FOE:
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case ALPHA_MMCSR_FOW:
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{
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pmap_emulate_reference(p, a0, user,
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a1 == ALPHA_MMCSR_FOW);
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goto out;
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}
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case ALPHA_MMCSR_INVALTRANS:
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case ALPHA_MMCSR_ACCESS:
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{
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@ -165,15 +165,11 @@ struct md_page {
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TAILQ_HEAD(,pv_entry) pv_list;
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};
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#define PV_TABLE_MOD 0x01 /* modified */
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#define PV_TABLE_REF 0x02 /* referenced */
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struct pmap {
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pt_entry_t *pm_lev1; /* KVA of lev0map */
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vm_object_t pm_pteobj; /* Container for pte's */
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TAILQ_HEAD(,pv_entry) pm_pvlist; /* list of mappings in pmap */
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int pm_count; /* reference count */
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int pm_flags; /* pmap flags */
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u_int32_t pm_active; /* active cpus */
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struct {
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u_int32_t asn:8; /* address space number */
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