Author: alc
Date: Wed Sep 18 07:25:04 2019
New Revision: 352475
URL: https://svnweb.freebsd.org/changeset/base/352475
Log:
MFC r350463
In pmap_advise(), when we encounter a superpage mapping, we first demote
the mapping and then destroy one of the 4 KB page mappings so that there
is a potential trigger for repromotion. Currently, we destroy the first
4 KB page mapping that falls within the (current) superpage mapping or the
virtual address range [sva, eva). However, I have found empirically that
destroying the last 4 KB mapping produces slightly better results,
specifically, more promotions and fewer failed promotion attempts.
Accordingly, this revision changes pmap_advise() to destroy the last 4 KB
page mapping. It also replaces some nearby uses of boolean_t with bool.
Modified:
stable/12/sys/amd64/amd64/pmap.c
stable/12/sys/arm64/arm64/pmap.c
stable/12/sys/i386/i386/pmap.c
Directory Properties:
stable/12/ (props changed)
Modified: stable/12/sys/amd64/amd64/pmap.c
==============================================================================
--- stable/12/sys/amd64/amd64/pmap.c Wed Sep 18 07:24:33 2019
(r352474)
+++ stable/12/sys/amd64/amd64/pmap.c Wed Sep 18 07:25:04 2019
(r352475)
@@ -7462,7 +7462,7 @@ pmap_advise(pmap_t pmap, vm_offset_t sva, vm_offset_t
pt_entry_t *pte, PG_A, PG_G, PG_M, PG_RW, PG_V;
vm_offset_t va, va_next;
vm_page_t m;
- boolean_t anychanged;
+ bool anychanged;
if (advice != MADV_DONTNEED && advice != MADV_FREE)
return;
@@ -7481,7 +7481,7 @@ pmap_advise(pmap_t pmap, vm_offset_t sva, vm_offset_t
PG_M = pmap_modified_bit(pmap);
PG_V = pmap_valid_bit(pmap);
PG_RW = pmap_rw_bit(pmap);
- anychanged = FALSE;
+ anychanged = false;
pmap_delayed_invl_start();
PMAP_LOCK(pmap);
for (; sva < eva; sva = va_next) {
@@ -7523,17 +7523,25 @@ pmap_advise(pmap_t pmap, vm_offset_t sva, vm_offset_t
/*
* Unless the page mappings are wired, remove the
* mapping to a single page so that a subsequent
- * access may repromote. Since the underlying page
- * table page is fully populated, this removal never
- * frees a page table page.
+ * access may repromote. Choosing the last page
+ * within the address range [sva, min(va_next, eva))
+ * generally results in more repromotions. Since the
+ * underlying page table page is fully populated, this
+ * removal never frees a page table page.
*/
if ((oldpde & PG_W) == 0) {
- pte = pmap_pde_to_pte(pde, sva);
+ va = eva;
+ if (va > va_next)
+ va = va_next;
+ va -= PAGE_SIZE;
+ KASSERT(va >= sva,
+ ("pmap_advise: no address gap"));
+ pte = pmap_pde_to_pte(pde, va);
KASSERT((*pte & PG_V) != 0,
("pmap_advise: invalid PTE"));
- pmap_remove_pte(pmap, pte, sva, *pde, NULL,
+ pmap_remove_pte(pmap, pte, va, *pde, NULL,
&lock);
- anychanged = TRUE;
+ anychanged = true;
}
if (lock != NULL)
rw_wunlock(lock);
@@ -7565,7 +7573,7 @@ pmap_advise(pmap_t pmap, vm_offset_t sva, vm_offset_t
if (va == va_next)
va = sva;
} else
- anychanged = TRUE;
+ anychanged = true;
continue;
maybe_invlrng:
if (va != va_next) {
Modified: stable/12/sys/arm64/arm64/pmap.c
==============================================================================
--- stable/12/sys/arm64/arm64/pmap.c Wed Sep 18 07:24:33 2019
(r352474)
+++ stable/12/sys/arm64/arm64/pmap.c Wed Sep 18 07:25:04 2019
(r352475)
@@ -4882,15 +4882,23 @@ pmap_advise(pmap_t pmap, vm_offset_t sva, vm_offset_t
/*
* Unless the page mappings are wired, remove the
* mapping to a single page so that a subsequent
- * access may repromote. Since the underlying page
- * table page is fully populated, this removal never
- * frees a page table page.
+ * access may repromote. Choosing the last page
+ * within the address range [sva, min(va_next, eva))
+ * generally results in more repromotions. Since the
+ * underlying page table page is fully populated, this
+ * removal never frees a page table page.
*/
if ((oldl2 & ATTR_SW_WIRED) == 0) {
- l3 = pmap_l2_to_l3(l2, sva);
+ va = eva;
+ if (va > va_next)
+ va = va_next;
+ va -= PAGE_SIZE;
+ KASSERT(va >= sva,
+ ("pmap_advise: no address gap"));
+ l3 = pmap_l2_to_l3(l2, va);
KASSERT(pmap_load(l3) != 0,
("pmap_advise: invalid PTE"));
- pmap_remove_l3(pmap, l3, sva, pmap_load(l2),
+ pmap_remove_l3(pmap, l3, va, pmap_load(l2),
NULL, &lock);
}
if (lock != NULL)
Modified: stable/12/sys/i386/i386/pmap.c
==============================================================================
--- stable/12/sys/i386/i386/pmap.c Wed Sep 18 07:24:33 2019
(r352474)
+++ stable/12/sys/i386/i386/pmap.c Wed Sep 18 07:25:04 2019
(r352475)
@@ -5246,19 +5246,19 @@ pmap_advise(pmap_t pmap, vm_offset_t sva, vm_offset_t
pt_entry_t *pte;
vm_offset_t va, pdnxt;
vm_page_t m;
- boolean_t anychanged, pv_lists_locked;
+ bool anychanged, pv_lists_locked;
if (advice != MADV_DONTNEED && advice != MADV_FREE)
return;
if (pmap_is_current(pmap))
- pv_lists_locked = FALSE;
+ pv_lists_locked = false;
else {
- pv_lists_locked = TRUE;
+ pv_lists_locked = true;
resume:
rw_wlock(&pvh_global_lock);
sched_pin();
}
- anychanged = FALSE;
+ anychanged = false;
PMAP_LOCK(pmap);
for (; sva < eva; sva = pdnxt) {
pdnxt = (sva + NBPDR) & ~PDRMASK;
@@ -5272,7 +5272,7 @@ resume:
if ((oldpde & PG_MANAGED) == 0)
continue;
if (!pv_lists_locked) {
- pv_lists_locked = TRUE;
+ pv_lists_locked = true;
if (!rw_try_wlock(&pvh_global_lock)) {
if (anychanged)
pmap_invalidate_all(pmap);
@@ -5291,16 +5291,24 @@ resume:
/*
* Unless the page mappings are wired, remove the
* mapping to a single page so that a subsequent
- * access may repromote. Since the underlying page
- * table page is fully populated, this removal never
- * frees a page table page.
+ * access may repromote. Choosing the last page
+ * within the address range [sva, min(pdnxt, eva))
+ * generally results in more repromotions. Since the
+ * underlying page table page is fully populated, this
+ * removal never frees a page table page.
*/
if ((oldpde & PG_W) == 0) {
- pte = pmap_pte_quick(pmap, sva);
+ va = eva;
+ if (va > pdnxt)
+ va = pdnxt;
+ va -= PAGE_SIZE;
+ KASSERT(va >= sva,
+ ("pmap_advise: no address gap"));
+ pte = pmap_pte_quick(pmap, va);
KASSERT((*pte & PG_V) != 0,
("pmap_advise: invalid PTE"));
- pmap_remove_pte(pmap, pte, sva, NULL);
- anychanged = TRUE;
+ pmap_remove_pte(pmap, pte, va, NULL);
+ anychanged = true;
}
}
if (pdnxt > eva)
@@ -5329,7 +5337,7 @@ resume:
if (va == pdnxt)
va = sva;
} else
- anychanged = TRUE;
+ anychanged = true;
continue;
maybe_invlrng:
if (va != pdnxt) {
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