| Message ID | 1589882610-7291-3-git-send-email-maobibo@loongson.cn (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [v4,1/4] MIPS: Do not flush tlb page when updating PTE entry | expand |
On Tue, 19 May 2020 18:03:29 +0800 Bibo Mao <maobibo@loongson.cn> wrote: > 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. > > --- a/arch/mips/include/asm/pgtable.h > +++ b/arch/mips/include/asm/pgtable.h > @@ -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; } > > --- a/include/asm-generic/pgtable.h > +++ b/include/asm-generic/pgtable.h > @@ -227,6 +227,21 @@ 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; > +} > +#endif Yup, that's neat enough. Thanks for making this change. It looks like all architectures include asm-generic/pgtable.h so that's fine. It's conventional to add a #define pte_sw_mkyoung pte_sw_mkyoung immediately above the #endif there, so we can't try to implement pte_sw_mkyoung() twice if this header gets included twice. But the header has #ifndef _ASM_GENERIC_PGTABLE_H around the whole thing so that should be OK.
On 05/20/2020 09:30 AM, Andrew Morton wrote: > On Tue, 19 May 2020 18:03:29 +0800 Bibo Mao <maobibo@loongson.cn> wrote: > >> 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. >> >> --- a/arch/mips/include/asm/pgtable.h >> +++ b/arch/mips/include/asm/pgtable.h >> @@ -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; } >> >> --- a/include/asm-generic/pgtable.h >> +++ b/include/asm-generic/pgtable.h >> @@ -227,6 +227,21 @@ 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; >> +} >> +#endif > > Yup, that's neat enough. Thanks for making this change. It looks like > all architectures include asm-generic/pgtable.h so that's fine. > > It's conventional to add a > > #define pte_sw_mkyoung pte_sw_mkyoung > > immediately above the #endif there, so we can't try to implement > pte_sw_mkyoung() twice if this header gets included twice. But the > header has #ifndef _ASM_GENERIC_PGTABLE_H around the whole thing so > that should be OK. Sure, will do, and thanks for your kindly help and guidance
diff --git a/arch/mips/include/asm/pgtable.h b/arch/mips/include/asm/pgtable.h index 0d625c2..755d534 100644 --- a/arch/mips/include/asm/pgtable.h +++ b/arch/mips/include/asm/pgtable.h @@ -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; } diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h index 329b8c8..2542ef1 100644 --- a/include/asm-generic/pgtable.h +++ b/include/asm-generic/pgtable.h @@ -227,6 +227,21 @@ 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; +} +#endif + #ifndef pte_savedwrite #define pte_savedwrite pte_write #endif diff --git a/mm/memory.c b/mm/memory.c index 2eb59a9..d9700b1 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -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 */
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: Bibo Mao <maobibo@loongson.cn> --- arch/mips/include/asm/pgtable.h | 2 ++ include/asm-generic/pgtable.h | 15 +++++++++++++++ mm/memory.c | 3 +++ 3 files changed, 20 insertions(+)