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riscv: 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.

1d5ebad06c made the change for amd64 and arm64.

Reviewed by:	markj, alc
MFC after:	1 week
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D36563
This commit is contained in:
Mitchell Horne 2022-10-05 14:10:45 -03:00
parent dd18b62cec
commit 95b1c27069
1 changed files with 31 additions and 20 deletions
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51
sys/riscv/riscv/pmap.c
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@ -3120,13 +3120,12 @@ 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)
{
@ -3144,18 +3143,20 @@ pmap_enter_2mpage(pmap_t pmap, vm_offset_t va, vm_page_t m, vm_prot_t prot,
if (va < VM_MAXUSER_ADDRESS)
new_l2 |= PTE_U;
return (pmap_enter_l2(pmap, va, new_l2, PMAP_ENTER_NOSLEEP |
PMAP_ENTER_NOREPLACE | PMAP_ENTER_NORECLAIM, NULL, lockp) ==
KERN_SUCCESS);
PMAP_ENTER_NOREPLACE | PMAP_ENTER_NORECLAIM, NULL, lockp));
}
/*
* 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_SHORTAGE 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.
*
* The parameter "m" is only used when creating a managed, writeable mapping.
*/
@ -3183,11 +3184,19 @@ pmap_enter_l2(pmap_t pmap, vm_offset_t va, pd_entry_t new_l2, u_int flags,
KASSERT(l2pg->ref_count > 1,
("pmap_enter_l2: l2pg's ref count is too low"));
if ((flags & PMAP_ENTER_NOREPLACE) != 0) {
l2pg->ref_count--;
CTR2(KTR_PMAP,
"pmap_enter_l2: failed to replace existing mapping"
" for va %#lx in pmap %p", va, pmap);
return (KERN_FAILURE);
if ((oldl2 & PTE_RWX) != 0) {
l2pg->ref_count--;
CTR2(KTR_PMAP,
"pmap_enter_l2: no space for va %#lx"
" in pmap %p", va, pmap);
return (KERN_NO_SPACE);
} else {
l2pg->ref_count--;
CTR2(KTR_PMAP, "pmap_enter_l2:"
" failed to replace existing mapping"
" for va %#lx in pmap %p", va, pmap);
return (KERN_FAILURE);
}
}
SLIST_INIT(&free);
if ((oldl2 & PTE_RWX) != 0)
@ -3280,6 +3289,7 @@ 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);
@ -3293,7 +3303,8 @@ 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,