Author: kib
Date: Sun Feb 19 03:33:20 2017
New Revision: 313933
URL: https://svnweb.freebsd.org/changeset/base/313933
Log:
Microoptimize amd64/pmap.c pmap_protect_pde().
For the loop that dirties vm_pages in case superpage was written to,
check the complete condition before the loop.
Reviewed by: alc
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Modified:
head/sys/amd64/amd64/pmap.c
Modified: head/sys/amd64/amd64/pmap.c
==============================================================================
--- head/sys/amd64/amd64/pmap.c Sun Feb 19 03:17:11 2017 (r313932)
+++ head/sys/amd64/amd64/pmap.c Sun Feb 19 03:33:20 2017 (r313933)
@@ -3998,12 +3998,12 @@ pmap_protect_pde(pmap_t pmap, pd_entry_t
anychanged = FALSE;
retry:
oldpde = newpde = *pde;
- if (oldpde & PG_MANAGED) {
+ if ((oldpde & (PG_MANAGED | PG_M | PG_RW)) ==
+ (PG_MANAGED | PG_M | PG_RW)) {
eva = sva + NBPDR;
for (va = sva, m = PHYS_TO_VM_PAGE(oldpde & PG_PS_FRAME);
va < eva; va += PAGE_SIZE, m++)
- if ((oldpde & (PG_M | PG_RW)) == (PG_M | PG_RW))
- vm_page_dirty(m);
+ vm_page_dirty(m);
}
if ((prot & VM_PROT_WRITE) == 0)
newpde &= ~(PG_RW | PG_M);
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