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Utilize pmap_enter(..., psind=1) in vm_fault_soft_fast() on amd64. (The

Browse Source 
Differential Revision discusses the benefits of this change.)

Add a function, vm_reserv_to_superpage(), that returns the superpage
containing the specified base page.

Reviewed by:	kib, markj
Tested by:	pho
MFC after:	10 days
Differential Revision:	https://reviews.freebsd.org/D11556
This commit is contained in:
Alan Cox 2017-07-23 16:28:13 +00:00
parent aca38eab8a
commit 8b5e1472d2
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=321386
3 changed files with 55 additions and 5 deletions
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45
sys/vm/vm_fault.c
View File

@ -266,8 +266,11 @@ static int
vm_fault_soft_fast(struct faultstate *fs, vm_offset_t vaddr, vm_prot_t prot,
int fault_type, int fault_flags, boolean_t wired, vm_page_t *m_hold)
{
vm_page_t m;
int rv;
vm_page_t m, m_map;
#if defined(__amd64__) && VM_NRESERVLEVEL > 0
vm_page_t m_super;
#endif
int flags, psind, rv;
MPASS(fs->vp == NULL);
m = vm_page_lookup(fs->first_object, fs->first_pindex);
@ -275,14 +278,46 @@ vm_fault_soft_fast(struct faultstate *fs, vm_offset_t vaddr, vm_prot_t prot,
if (m == NULL || ((prot & VM_PROT_WRITE) != 0 &&
vm_page_busied(m)) || m->valid != VM_PAGE_BITS_ALL)
return (KERN_FAILURE);
rv = pmap_enter(fs->map->pmap, vaddr, m, prot, fault_type |
PMAP_ENTER_NOSLEEP | (wired ? PMAP_ENTER_WIRED : 0), 0);
m_map = m;
psind = 0;
#if defined(__amd64__) && VM_NRESERVLEVEL > 0
if ((m->flags & PG_FICTITIOUS) == 0 &&
(m_super = vm_reserv_to_superpage(m)) != NULL &&
rounddown2(vaddr, pagesizes[m_super->psind]) >= fs->entry->start &&
roundup2(vaddr + 1, pagesizes[m_super->psind]) <= fs->entry->end &&
(vaddr & (pagesizes[m_super->psind] - 1)) == (VM_PAGE_TO_PHYS(m) &
(pagesizes[m_super->psind] - 1)) &&
pmap_ps_enabled(fs->map->pmap)) {
flags = PS_ALL_VALID;
if ((prot & VM_PROT_WRITE) != 0) {
/*
* Create a superpage mapping allowing write access
* only if none of the constituent pages are busy and
* all of them are already dirty (except possibly for
* the page that was faulted on).
*/
flags |= PS_NONE_BUSY;
if ((fs->first_object->flags & OBJ_UNMANAGED) == 0)
flags |= PS_ALL_DIRTY;
}
if (vm_page_ps_test(m_super, flags, m)) {
m_map = m_super;
psind = m_super->psind;
vaddr = rounddown2(vaddr, pagesizes[psind]);
/* Preset the modified bit for dirty superpages. */
if ((flags & PS_ALL_DIRTY) != 0)
fault_type |= VM_PROT_WRITE;
}
}
#endif
rv = pmap_enter(fs->map->pmap, vaddr, m_map, prot, fault_type |
PMAP_ENTER_NOSLEEP | (wired ? PMAP_ENTER_WIRED : 0), psind);
if (rv != KERN_SUCCESS)
return (rv);
vm_fault_fill_hold(m_hold, m);
vm_fault_dirty(fs->entry, m, prot, fault_type, fault_flags, false);
VM_OBJECT_RUNLOCK(fs->first_object);
if (!wired)
if (psind == 0 && !wired)
vm_fault_prefault(fs, vaddr, PFBAK, PFFOR);
vm_map_lookup_done(fs->map, fs->entry);
curthread->td_ru.ru_minflt++;

14
sys/vm/vm_reserv.c
View File

@ -1121,4 +1121,18 @@ vm_reserv_startup(vm_offset_t *vaddr, vm_paddr_t end, vm_paddr_t high_water)
return (new_end);
}
/*
* Returns the superpage containing the given page.
*/
vm_page_t
vm_reserv_to_superpage(vm_page_t m)
{
vm_reserv_t rv;
VM_OBJECT_ASSERT_LOCKED(m->object);
rv = vm_reserv_from_page(m);
return (rv->object == m->object && rv->popcnt == VM_LEVEL_0_NPAGES ?
rv->pages : NULL);
}
#endif /* VM_NRESERVLEVEL > 0 */

1
sys/vm/vm_reserv.h
View File

@ -64,6 +64,7 @@ void vm_reserv_rename(vm_page_t m, vm_object_t new_object,
int vm_reserv_size(int level);
vm_paddr_t vm_reserv_startup(vm_offset_t *vaddr, vm_paddr_t end,
vm_paddr_t high_water);
vm_page_t vm_reserv_to_superpage(vm_page_t m);
#endif /* VM_NRESERVLEVEL > 0 */
#endif /* _KERNEL */