Author: alc
Date: Thu Jul 15 16:25:51 2010
New Revision: 210124
URL: http://svn.freebsd.org/changeset/base/210124
Log:
Optimize pmap_remove()'s handling of PG_G mappings. Specifically,
instead of calling pmap_invalidate_page() for each PG_G mapping, call
pmap_invalidate_range() for each range of PG_G mappings. In addition,
eliminate a redundant call to pmap_invalidate_page(). Both
pmap_remove_pte() and pmap_remove_page() called pmap_invalidate_page()
when the mapping had the PG_G attribute. Now, only pmap_remove_page()
calls pmap_invalidate_page(). Altogether, these changes eliminate 53%
of the TLB shootdowns for a "buildworld" on a ZFS file system. On
FFS, the reduction is 3%.
MFC after: 6 weeks
Modified:
head/sys/amd64/amd64/pmap.c
Modified: head/sys/amd64/amd64/pmap.c
==============================================================================
--- head/sys/amd64/amd64/pmap.c Thu Jul 15 14:43:12 2010 (r210123)
+++ head/sys/amd64/amd64/pmap.c Thu Jul 15 16:25:51 2010 (r210124)
@@ -2602,12 +2602,6 @@ pmap_remove_pte(pmap_t pmap, pt_entry_t
oldpte = pte_load_clear(ptq);
if (oldpte & PG_W)
pmap->pm_stats.wired_count -= 1;
- /*
- * Machines that don't support invlpg, also don't support
- * PG_G.
- */
- if (oldpte & PG_G)
- pmap_invalidate_page(kernel_pmap, va);
pmap_resident_count_dec(pmap, 1);
if (oldpte & PG_MANAGED) {
m = PHYS_TO_VM_PAGE(oldpte & PG_FRAME);
@@ -2647,7 +2641,7 @@ pmap_remove_page(pmap_t pmap, vm_offset_
void
pmap_remove(pmap_t pmap, vm_offset_t sva, vm_offset_t eva)
{
- vm_offset_t va_next;
+ vm_offset_t va, va_next;
pml4_entry_t *pml4e;
pdp_entry_t *pdpe;
pd_entry_t ptpaddr, *pde;
@@ -2748,20 +2742,27 @@ pmap_remove(pmap_t pmap, vm_offset_t sva
if (va_next > eva)
va_next = eva;
+ va = va_next;
for (pte = pmap_pde_to_pte(pde, sva); sva != va_next; pte++,
sva += PAGE_SIZE) {
- if (*pte == 0)
+ if (*pte == 0) {
+ if (va != va_next) {
+ pmap_invalidate_range(pmap, va, sva);
+ va = va_next;
+ }
continue;
-
- /*
- * The TLB entry for a PG_G mapping is invalidated
- * by pmap_remove_pte().
- */
+ }
if ((*pte & PG_G) == 0)
anyvalid = 1;
- if (pmap_remove_pte(pmap, pte, sva, ptpaddr, &free))
+ else if (va == va_next)
+ va = sva;
+ if (pmap_remove_pte(pmap, pte, sva, ptpaddr, &free)) {
+ sva += PAGE_SIZE;
break;
+ }
}
+ if (va != va_next)
+ pmap_invalidate_range(pmap, va, sva);
}
out:
if (anyvalid)
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