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[PATCH] x86_64: avoid some atomic operations during address space destruction 

Any architecture that has hardware updated A/D bits that require
synchronization against other processors during PTE operations can benefit
from doing non-atomic PTE updates during address space destruction.
Originally done on i386, now ported to x86_64.

Doing a read/write pair instead of an xchg() operation saves the implicit
lock, which turns out to be a big win on 32-bit (esp w PAE).

Signed-off-by: Zachary Amsden <zach@vmware.com>
Cc: Andi Kleen <ak@muc.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Zachary Amsden 2005-09-03 15:55:06 -07:00 committed by Linus Torvalds
parent a600388d28
commit 61e06037e7
1 changed files with 14 additions and 0 deletions
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14
include/asm-x86_64/pgtable.h
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@ -104,6 +104,19 @@ extern inline void pgd_clear (pgd_t * pgd)
((unsigned long) __va(pud_val(pud) & PHYSICAL_PAGE_MASK))
#define ptep_get_and_clear(mm,addr,xp) __pte(xchg(&(xp)->pte, 0))
static inline pte_t ptep_get_and_clear_full(struct mm_struct *mm, unsigned long addr, pte_t *ptep, int full)
{
pte_t pte;
if (full) {
pte = *ptep;
*ptep = __pte(0);
} else {
pte = ptep_get_and_clear(mm, addr, ptep);
}
return pte;
}
#define pte_same(a, b) ((a).pte == (b).pte)
#define PMD_SIZE (1UL << PMD_SHIFT)
@ -434,6 +447,7 @@ extern int kern_addr_valid(unsigned long addr);
#define __HAVE_ARCH_PTEP_TEST_AND_CLEAR_YOUNG
#define __HAVE_ARCH_PTEP_TEST_AND_CLEAR_DIRTY
#define __HAVE_ARCH_PTEP_GET_AND_CLEAR
#define __HAVE_ARCH_PTEP_GET_AND_CLEAR_FULL
#define __HAVE_ARCH_PTEP_SET_WRPROTECT
#define __HAVE_ARCH_PTE_SAME
#include <asm-generic/pgtable.h>