[PATCH] x86_64: avoid some atomic operations during address space destruction (61e06037) · Commits · 戴 / test

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>

include/asm-x86_64/pgtable.h

+14 −0

Original line number	Diff line number	Diff line
		@@ -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>

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