Commit 44bf431b authored by Bibo Mao's avatar Bibo Mao Committed by Thomas Bogendoerfer
Browse files

mm/memory.c: Add memory read privilege on page fault handling 



Here add pte_sw_mkyoung function to make page readable on MIPS
platform during page fault handling. This patch improves page
fault latency about 10% on my MIPS machine with lmbench
lat_pagefault case.

It is noop function on other arches, there is no negative
influence on those architectures.

Signed-off-by: default avatarBibo Mao <maobibo@loongson.cn>
Acked-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarThomas Bogendoerfer <tsbogend@alpha.franken.de>
parent 7df67697

arch/mips/include/asm/pgtable.h

+2 −0
Original line number Diff line number Diff line
@@ -414,6 +414,8 @@ static inline pte_t pte_mkyoung(pte_t pte) 
	return pte;

}



#define pte_sw_mkyoung	pte_mkyoung



#ifdef CONFIG_MIPS_HUGE_TLB_SUPPORT

static inline int pte_huge(pte_t pte)	{ return pte_val(pte) & _PAGE_HUGE; }

include/asm-generic/pgtable.h

+16 −0
Original line number Diff line number Diff line
@@ -244,6 +244,22 @@ static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long addres 
}

#endif



/*

 * On some architectures hardware does not set page access bit when accessing

 * memory page, it is responsibilty of software setting this bit. It brings

 * out extra page fault penalty to track page access bit. For optimization page

 * access bit can be set during all page fault flow on these arches.

 * To be differentiate with macro pte_mkyoung, this macro is used on platforms

 * where software maintains page access bit.

 */

#ifndef pte_sw_mkyoung

static inline pte_t pte_sw_mkyoung(pte_t pte)

{

	return pte;

}

#define pte_sw_mkyoung	pte_sw_mkyoung

#endif



#ifndef pte_savedwrite

#define pte_savedwrite pte_write

#endif

mm/memory.c

+3 −0
Original line number Diff line number Diff line
@@ -2704,6 +2704,7 @@ static vm_fault_t wp_page_copy(struct vm_fault *vmf) 
		}

		flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte));

		entry = mk_pte(new_page, vma->vm_page_prot);

		entry = pte_sw_mkyoung(entry);

		entry = maybe_mkwrite(pte_mkdirty(entry), vma);

		/*

		 * Clear the pte entry and flush it first, before updating the
@@ -3378,6 +3379,7 @@ static vm_fault_t do_anonymous_page(struct vm_fault *vmf) 
	__SetPageUptodate(page);



	entry = mk_pte(page, vma->vm_page_prot);

	entry = pte_sw_mkyoung(entry);

	if (vma->vm_flags & VM_WRITE)

		entry = pte_mkwrite(pte_mkdirty(entry));
@@ -3660,6 +3662,7 @@ vm_fault_t alloc_set_pte(struct vm_fault *vmf, struct mem_cgroup *memcg, 


	flush_icache_page(vma, page);

	entry = mk_pte(page, vma->vm_page_prot);

	entry = pte_sw_mkyoung(entry);

	if (write)

		entry = maybe_mkwrite(pte_mkdirty(entry), vma);

	/* copy-on-write page */

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