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Simplify pv_entry removal or ARMv6/v7:

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- PGA_WRITEABLE indicates that there *might be* a writable mapping for the
  particular page, so to avoid frequent sweeping of the pv_entries whenever
  pmap_nuke_pv(), pmap_modify_pv(), etc. is called, it is sufficient to
  clear that flag if there are no managed mappings for that page anymore
  (notice that only pmap_enter is authorized to set this flag).
- Avoid redundant checking for PVF_WIRED flag when this flag cannot be set
  anyway.
- Clear PGA_WRITEABLE only once for each vm_page instead of multiple,
  redundant clearing it in loop when there are no writeable mappings
  to that page anymore.

Submitted by:	Zbigniew Bodek <zbb@semihalf.com>
Reviewed by:	gber
Sponsored by:	The FreeBSD Foundation, Semihalf
This commit is contained in:
Rafal Jaworowski 2013-08-19 14:56:17 +00:00
parent 5fc98a7895
commit 06b6590c4a
1 changed files with 18 additions and 36 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

54
sys/arm/arm/pmap-v6.c
View File

@ -1072,39 +1072,22 @@ pmap_set_prot(pt_entry_t *ptep, vm_prot_t prot, uint8_t user)
* => caller should NOT adjust pmap's wire_count
* => we return the removed pve
*/
static void
pmap_nuke_pv(struct vm_page *m, pmap_t pmap, struct pv_entry *pve)
{
rw_assert(&pvh_global_lock, RA_WLOCKED);
PMAP_ASSERT_LOCKED(pmap);
TAILQ_REMOVE(&m->md.pv_list, pve, pv_list);
if (pve->pv_flags & PVF_WIRED)
--pmap->pm_stats.wired_count;
if (pve->pv_flags & PVF_WRITE) {
TAILQ_FOREACH(pve, &m->md.pv_list, pv_list)
if (pve->pv_flags & PVF_WRITE)
break;
if (!pve) {
vm_page_aflag_clear(m, PGA_WRITEABLE);
}
}
}
static struct pv_entry *
pmap_remove_pv(struct vm_page *m, pmap_t pmap, vm_offset_t va)
{
struct pv_entry *pve;
rw_assert(&pvh_global_lock, RA_WLOCKED);
PMAP_ASSERT_LOCKED(pmap);
pve = pmap_find_pv(m, pmap, va); /* find corresponding pve */
if (pve != NULL)
pmap_nuke_pv(m, pmap, pve);
if (pve != NULL) {
TAILQ_REMOVE(&m->md.pv_list, pve, pv_list);
if (pve->pv_flags & PVF_WIRED)
--pmap->pm_stats.wired_count;
}
if (TAILQ_EMPTY(&m->md.pv_list))
vm_page_aflag_clear(m, PGA_WRITEABLE);
return(pve); /* return removed pve */
}
@ -1143,14 +1126,6 @@ pmap_modify_pv(struct vm_page *m, pmap_t pmap, vm_offset_t va,
else
--pmap->pm_stats.wired_count;
}
if ((oflags & PVF_WRITE) && !(flags & PVF_WRITE)) {
TAILQ_FOREACH(npv, &m->md.pv_list, pv_list) {
if (npv->pv_flags & PVF_WRITE)
break;
}
if (!npv)
vm_page_aflag_clear(m, PGA_WRITEABLE);
}
return (oflags);
}
@ -2062,7 +2037,9 @@ pmap_remove_pages(pmap_t pmap)
pv_entry_count--;
pmap->pm_stats.resident_count--;
pc->pc_map[field] |= bitmask;
pmap_nuke_pv(m, pmap, pv);
TAILQ_REMOVE(&m->md.pv_list, pv, pv_list);
if (TAILQ_EMPTY(&m->md.pv_list))
vm_page_aflag_clear(m, PGA_WRITEABLE);
pmap_free_l2_bucket(pmap, l2b, 1);
}
}
@ -2458,7 +2435,9 @@ pmap_remove_all(vm_page_t m)
PTE_SYNC(ptep);
pmap_free_l2_bucket(pmap, l2b, 1);
pmap->pm_stats.resident_count--;
pmap_nuke_pv(m, pmap, pv);
TAILQ_REMOVE(&m->md.pv_list, pv, pv_list);
if (pv->pv_flags & PVF_WIRED)
pmap->pm_stats.wired_count--;
pmap_free_pv_entry(pmap, pv);
PMAP_UNLOCK(pmap);
}
@ -2469,6 +2448,7 @@ pmap_remove_all(vm_page_t m)
else
cpu_tlb_flushD();
}
vm_page_aflag_clear(m, PGA_WRITEABLE);
rw_wunlock(&pvh_global_lock);
}
@ -3338,7 +3318,9 @@ pmap_pv_reclaim(pmap_t locked_pmap)
"va %x pte %x", va, *ptep));
*ptep = 0;
PTE_SYNC(ptep);
pmap_nuke_pv(m, pmap, pv);
TAILQ_REMOVE(&m->md.pv_list, pv, pv_list);
if (TAILQ_EMPTY(&m->md.pv_list))
vm_page_aflag_clear(m, PGA_WRITEABLE);
pc->pc_map[field] |= 1UL << bit;
freed++;
}