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pmap: optimize MADV_WILLNEED on existing superpages

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Specifically, avoid pointless calls to pmap_enter_quick_locked() when
madvise(MADV_WILLNEED) is applied to an existing superpage mapping.

Reported by:	mhorne
Reviewed by:	kib, markj
MFC after:	1 week
Differential Revision:	https://reviews.freebsd.org/D36801
This commit is contained in:
Alan Cox 2022-09-30 01:54:02 -05:00
parent 8707cb19e6
commit 1d5ebad06c
2 changed files with 75 additions and 48 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

64
sys/amd64/amd64/pmap.c
View File

@ -1258,7 +1258,7 @@ static boolean_t pmap_demote_pde_locked(pmap_t pmap, pd_entry_t *pde,
vm_offset_t va, struct rwlock **lockp);
static boolean_t pmap_demote_pdpe(pmap_t pmap, pdp_entry_t *pdpe,
vm_offset_t va);
static bool pmap_enter_2mpage(pmap_t pmap, vm_offset_t va, vm_page_t m,
static int pmap_enter_2mpage(pmap_t pmap, vm_offset_t va, vm_page_t m,
vm_prot_t prot, struct rwlock **lockp);
static int pmap_enter_pde(pmap_t pmap, vm_offset_t va, pd_entry_t newpde,
u_int flags, vm_page_t m, struct rwlock **lockp);
@ -7271,13 +7271,12 @@ pmap_enter(pmap_t pmap, vm_offset_t va, vm_page_t m, vm_prot_t prot,
}
/*
* Tries to create a read- and/or execute-only 2MB page mapping. Returns true
* if successful. Returns false if (1) a page table page cannot be allocated
* without sleeping, (2) a mapping already exists at the specified virtual
* address, or (3) a PV entry cannot be allocated without reclaiming another
* PV entry.
* Tries to create a read- and/or execute-only 2MB page mapping. Returns
* KERN_SUCCESS if the mapping was created. Otherwise, returns an error
* value. See pmap_enter_pde() for the possible error values when "no sleep",
* "no replace", and "no reclaim" are specified.
*/
static bool
static int
pmap_enter_2mpage(pmap_t pmap, vm_offset_t va, vm_page_t m, vm_prot_t prot,
struct rwlock **lockp)
{
@ -7295,8 +7294,7 @@ pmap_enter_2mpage(pmap_t pmap, vm_offset_t va, vm_page_t m, vm_prot_t prot,
if (va < VM_MAXUSER_ADDRESS)
newpde |= PG_U;
return (pmap_enter_pde(pmap, va, newpde, PMAP_ENTER_NOSLEEP |
PMAP_ENTER_NOREPLACE | PMAP_ENTER_NORECLAIM, NULL, lockp) ==
KERN_SUCCESS);
PMAP_ENTER_NOREPLACE | PMAP_ENTER_NORECLAIM, NULL, lockp));
}
/*
@ -7319,12 +7317,19 @@ pmap_every_pte_zero(vm_paddr_t pa)
/*
* Tries to create the specified 2MB page mapping. Returns KERN_SUCCESS if
* the mapping was created, and either KERN_FAILURE or KERN_RESOURCE_SHORTAGE
* otherwise. Returns KERN_FAILURE if PMAP_ENTER_NOREPLACE was specified and
* a mapping already exists at the specified virtual address. Returns
* KERN_RESOURCE_SHORTAGE if PMAP_ENTER_NOSLEEP was specified and a page table
* page allocation failed. Returns KERN_RESOURCE_SHORTAGE if
* PMAP_ENTER_NORECLAIM was specified and a PV entry allocation failed.
* the mapping was created, and one of KERN_FAILURE, KERN_NO_SPACE,
* KERN_PROTECTION_FAILURE, or KERN_RESOURCE_FAILURE otherwise. Returns
* KERN_FAILURE if either (1) PMAP_ENTER_NOREPLACE was specified and a 4KB
* page mapping already exists within the 2MB virtual address range starting
* at the specified virtual address or (2) the requested 2MB page mapping is
* not supported due to hardware errata. Returns KERN_NO_SPACE if
* PMAP_ENTER_NOREPLACE was specified and a 2MB page mapping already exists at
* the specified virtual address. Returns KERN_PROTECTION_FAILURE if the PKRU
* settings are not the same across the 2MB virtual address range starting at
* the specified virtual address. Returns KERN_RESOURCE_SHORTAGE if either
* (1) PMAP_ENTER_NOSLEEP was specified and a page table page allocation
* failed or (2) PMAP_ENTER_NORECLAIM was specified and a PV entry allocation
* failed.
*
* The parameter "m" is only used when creating a managed, writeable mapping.
*/
@ -7380,14 +7385,23 @@ pmap_enter_pde(pmap_t pmap, vm_offset_t va, pd_entry_t newpde, u_int flags,
if ((oldpde & PG_V) != 0) {
KASSERT(pdpg == NULL || pdpg->ref_count > 1,
("pmap_enter_pde: pdpg's reference count is too low"));
if ((flags & PMAP_ENTER_NOREPLACE) != 0 && (va <
VM_MAXUSER_ADDRESS || (oldpde & PG_PS) != 0 ||
!pmap_every_pte_zero(oldpde & PG_FRAME))) {
if (pdpg != NULL)
pdpg->ref_count--;
CTR2(KTR_PMAP, "pmap_enter_pde: failure for va %#lx"
" in pmap %p", va, pmap);
return (KERN_FAILURE);
if ((flags & PMAP_ENTER_NOREPLACE) != 0) {
if ((oldpde & PG_PS) != 0) {
if (pdpg != NULL)
pdpg->ref_count--;
CTR2(KTR_PMAP,
"pmap_enter_pde: no space for va %#lx"
" in pmap %p", va, pmap);
return (KERN_NO_SPACE);
} else if (va < VM_MAXUSER_ADDRESS ||
!pmap_every_pte_zero(oldpde & PG_FRAME)) {
if (pdpg != NULL)
pdpg->ref_count--;
CTR2(KTR_PMAP,
"pmap_enter_pde: failure for va %#lx"
" in pmap %p", va, pmap);
return (KERN_FAILURE);
}
}
/* Break the existing mapping(s). */
SLIST_INIT(&free);
@ -7482,6 +7496,7 @@ pmap_enter_object(pmap_t pmap, vm_offset_t start, vm_offset_t end,
vm_offset_t va;
vm_page_t m, mpte;
vm_pindex_t diff, psize;
int rv;
VM_OBJECT_ASSERT_LOCKED(m_start->object);
@ -7494,7 +7509,8 @@ pmap_enter_object(pmap_t pmap, vm_offset_t start, vm_offset_t end,
va = start + ptoa(diff);
if ((va & PDRMASK) == 0 && va + NBPDR <= end &&
m->psind == 1 && pmap_ps_enabled(pmap) &&
pmap_enter_2mpage(pmap, va, m, prot, &lock))
((rv = pmap_enter_2mpage(pmap, va, m, prot, &lock)) ==
KERN_SUCCESS || rv == KERN_NO_SPACE))
m = &m[NBPDR / PAGE_SIZE - 1];
else
mpte = pmap_enter_quick_locked(pmap, va, m, prot,

59
sys/arm64/arm64/pmap.c
View File

@ -4419,13 +4419,12 @@ pmap_enter(pmap_t pmap, vm_offset_t va, vm_page_t m, vm_prot_t prot,
}
/*
* Tries to create a read- and/or execute-only 2MB page mapping. Returns true
* if successful. Returns false if (1) a page table page cannot be allocated
* without sleeping, (2) a mapping already exists at the specified virtual
* address, or (3) a PV entry cannot be allocated without reclaiming another
* PV entry.
* Tries to create a read- and/or execute-only 2MB page mapping. Returns
* KERN_SUCCESS if the mapping was created. Otherwise, returns an error
* value. See pmap_enter_l2() for the possible error values when "no sleep",
* "no replace", and "no reclaim" are specified.
*/
static bool
static int
pmap_enter_2mpage(pmap_t pmap, vm_offset_t va, vm_page_t m, vm_prot_t prot,
struct rwlock **lockp)
{
@ -4453,8 +4452,7 @@ pmap_enter_2mpage(pmap_t pmap, vm_offset_t va, vm_page_t m, vm_prot_t prot,
if (pmap != kernel_pmap)
new_l2 |= ATTR_S1_nG;
return (pmap_enter_l2(pmap, va, new_l2, PMAP_ENTER_NOSLEEP |
PMAP_ENTER_NOREPLACE | PMAP_ENTER_NORECLAIM, m, lockp) ==
KERN_SUCCESS);
PMAP_ENTER_NOREPLACE | PMAP_ENTER_NORECLAIM, m, lockp));
}
/*
@ -4477,12 +4475,15 @@ pmap_every_pte_zero(vm_paddr_t pa)
/*
* Tries to create the specified 2MB page mapping. Returns KERN_SUCCESS if
* the mapping was created, and either KERN_FAILURE or KERN_RESOURCE_SHORTAGE
* otherwise. Returns KERN_FAILURE if PMAP_ENTER_NOREPLACE was specified and
* a mapping already exists at the specified virtual address. Returns
* KERN_RESOURCE_SHORTAGE if PMAP_ENTER_NOSLEEP was specified and a page table
* page allocation failed. Returns KERN_RESOURCE_SHORTAGE if
* PMAP_ENTER_NORECLAIM was specified and a PV entry allocation failed.
* the mapping was created, and one of KERN_FAILURE, KERN_NO_SPACE, or
* KERN_RESOURCE_FAILURE otherwise. Returns KERN_FAILURE if
* PMAP_ENTER_NOREPLACE was specified and a 4KB page mapping already exists
* within the 2MB virtual address range starting at the specified virtual
* address. Returns KERN_NO_SPACE if PMAP_ENTER_NOREPLACE was specified and a
* 2MB page mapping already exists at the specified virtual address. Returns
* KERN_RESOURCE_SHORTAGE if either (1) PMAP_ENTER_NOSLEEP was specified and a
* page table page allocation failed or (2) PMAP_ENTER_NORECLAIM was specified
* and a PV entry allocation failed.
*/
static int
pmap_enter_l2(pmap_t pmap, vm_offset_t va, pd_entry_t new_l2, u_int flags,
@ -4509,15 +4510,23 @@ pmap_enter_l2(pmap_t pmap, vm_offset_t va, pd_entry_t new_l2, u_int flags,
if ((old_l2 = pmap_load(l2)) != 0) {
KASSERT(l2pg == NULL || l2pg->ref_count > 1,
("pmap_enter_l2: l2pg's ref count is too low"));
if ((flags & PMAP_ENTER_NOREPLACE) != 0 &&
(!ADDR_IS_KERNEL(va) ||
(old_l2 & ATTR_DESCR_MASK) == L2_BLOCK ||
!pmap_every_pte_zero(old_l2 & ~ATTR_MASK))) {
if (l2pg != NULL)
l2pg->ref_count--;
CTR2(KTR_PMAP, "pmap_enter_l2: failure for va %#lx"
" in pmap %p", va, pmap);
return (KERN_FAILURE);
if ((flags & PMAP_ENTER_NOREPLACE) != 0) {
if ((old_l2 & ATTR_DESCR_MASK) == L2_BLOCK) {
if (l2pg != NULL)
l2pg->ref_count--;
CTR2(KTR_PMAP,
"pmap_enter_l2: no space for va %#lx"
" in pmap %p", va, pmap);
return (KERN_NO_SPACE);
} else if (!ADDR_IS_KERNEL(va) ||
!pmap_every_pte_zero(old_l2 & ~ATTR_MASK)) {
if (l2pg != NULL)
l2pg->ref_count--;
CTR2(KTR_PMAP,
"pmap_enter_l2: failure for va %#lx"
" in pmap %p", va, pmap);
return (KERN_FAILURE);
}
}
SLIST_INIT(&free);
if ((old_l2 & ATTR_DESCR_MASK) == L2_BLOCK)
@ -4617,6 +4626,7 @@ pmap_enter_object(pmap_t pmap, vm_offset_t start, vm_offset_t end,
vm_offset_t va;
vm_page_t m, mpte;
vm_pindex_t diff, psize;
int rv;
VM_OBJECT_ASSERT_LOCKED(m_start->object);
@ -4629,7 +4639,8 @@ pmap_enter_object(pmap_t pmap, vm_offset_t start, vm_offset_t end,
va = start + ptoa(diff);
if ((va & L2_OFFSET) == 0 && va + L2_SIZE <= end &&
m->psind == 1 && pmap_ps_enabled(pmap) &&
pmap_enter_2mpage(pmap, va, m, prot, &lock))
((rv = pmap_enter_2mpage(pmap, va, m, prot, &lock)) ==
KERN_SUCCESS || rv == KERN_NO_SPACE))
m = &m[L2_SIZE / PAGE_SIZE - 1];
else
mpte = pmap_enter_quick_locked(pmap, va, m, prot, mpte,