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Date: Tue, 25 Mar 2014 12:20:15 +0530 From: Madhavan Srinivasan <maddy@...ux.vnet.ibm.com> To: linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org, linux-mm@...ck.org, linux-arch@...r.kernel.org, x86@...nel.org Cc: benh@...nel.crashing.org, paulus@...ba.org, kirill.shutemov@...ux.intel.com, rusty@...tcorp.com.au, akpm@...ux-foundation.org, riel@...hat.com, mgorman@...e.de, ak@...ux.intel.com, peterz@...radead.org, mingo@...nel.org, Madhavan Srinivasan <maddy@...ux.vnet.ibm.com> Subject: [PATCH 1/1] mm: move FAULT_AROUND_ORDER to arch/ Kirill A. Shutemov with the commit 96bacfe542 introduced vm_ops->map_pages() for mapping easy accessible pages around fault address in hope to reduce number of minor page faults. Based on his workload runs, suggested FAULT_AROUND_ORDER (knob to control the numbers of pages to map) is 4. This patch moves the FAULT_AROUND_ORDER macro to arch/ for architecture maintainers to decide on suitable FAULT_AROUND_ORDER value based on performance data for that architecture. Signed-off-by: Madhavan Srinivasan <maddy@...ux.vnet.ibm.com> --- arch/powerpc/include/asm/pgtable.h | 6 ++++++ arch/x86/include/asm/pgtable.h | 5 +++++ include/asm-generic/pgtable.h | 10 ++++++++++ mm/memory.c | 2 -- 4 files changed, 21 insertions(+), 2 deletions(-) diff --git a/arch/powerpc/include/asm/pgtable.h b/arch/powerpc/include/asm/pgtable.h index 3ebb188..9fcbd48 100644 --- a/arch/powerpc/include/asm/pgtable.h +++ b/arch/powerpc/include/asm/pgtable.h @@ -19,6 +19,12 @@ struct mm_struct; #endif /* + * With a few real world workloads that were run, + * the performance data showed that a value of 3 is more advantageous. + */ +#define FAULT_AROUND_ORDER 3 + +/* * We save the slot number & secondary bit in the second half of the * PTE page. We use the 8 bytes per each pte entry. */ diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h index 938ef1d..8387a65 100644 --- a/arch/x86/include/asm/pgtable.h +++ b/arch/x86/include/asm/pgtable.h @@ -7,6 +7,11 @@ #include <asm/pgtable_types.h> /* + * Based on Kirill's test results, fault around order is set to 4 + */ +#define FAULT_AROUND_ORDER 4 + +/* * Macro to mark a page protection value as UC- */ #define pgprot_noncached(prot) \ diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h index 1ec08c1..62f7f07 100644 --- a/include/asm-generic/pgtable.h +++ b/include/asm-generic/pgtable.h @@ -7,6 +7,16 @@ #include <linux/mm_types.h> #include <linux/bug.h> + +/* + * Fault around order is a control knob to decide the fault around pages. + * Default value is set to 0UL (disabled), but the arch can override it as + * desired. + */ +#ifndef FAULT_AROUND_ORDER +#define FAULT_AROUND_ORDER 0UL +#endif + /* * On almost all architectures and configurations, 0 can be used as the * upper ceiling to free_pgtables(): on many architectures it has the same diff --git a/mm/memory.c b/mm/memory.c index b02c584..fd79ffc 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3358,8 +3358,6 @@ void do_set_pte(struct vm_area_struct *vma, unsigned long address, update_mmu_cache(vma, address, pte); } -#define FAULT_AROUND_ORDER 4 - #ifdef CONFIG_DEBUG_FS static unsigned int fault_around_order = FAULT_AROUND_ORDER; -- 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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