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Date: Sun, 1 Apr 2018 19:30:33 -0700 From: Jia He <hejianet@...il.com> To: Russell King <linux@...linux.org.uk>, Catalin Marinas <catalin.marinas@....com>, Will Deacon <will.deacon@....com>, Mark Rutland <mark.rutland@....com>, Ard Biesheuvel <ard.biesheuvel@...aro.org>, Andrew Morton <akpm@...ux-foundation.org>, Michal Hocko <mhocko@...e.com> Cc: Wei Yang <richard.weiyang@...il.com>, Kees Cook <keescook@...omium.org>, Laura Abbott <labbott@...hat.com>, Vladimir Murzin <vladimir.murzin@....com>, Philip Derrin <philip@....systems>, Grygorii Strashko <grygorii.strashko@...aro.org>, AKASHI Takahiro <takahiro.akashi@...aro.org>, James Morse <james.morse@....com>, Steve Capper <steve.capper@....com>, Pavel Tatashin <pasha.tatashin@...cle.com>, Gioh Kim <gi-oh.kim@...fitbricks.com>, Vlastimil Babka <vbabka@...e.cz>, Mel Gorman <mgorman@...e.de>, Johannes Weiner <hannes@...xchg.org>, Kemi Wang <kemi.wang@...el.com>, Petr Tesarik <ptesarik@...e.com>, YASUAKI ISHIMATSU <yasu.isimatu@...il.com>, Andrey Ryabinin <aryabinin@...tuozzo.com>, Nikolay Borisov <nborisov@...e.com>, Daniel Jordan <daniel.m.jordan@...cle.com>, Daniel Vacek <neelx@...hat.com>, Eugeniu Rosca <erosca@...adit-jv.com>, linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, linux-mm@...ck.org, Jia He <hejianet@...il.com>, Jia He <jia.he@...-semitech.com> Subject: [PATCH v5 2/5] arm: arm64: page_alloc: reduce unnecessary binary search in memblock_next_valid_pfn() Commit b92df1de5d28 ("mm: page_alloc: skip over regions of invalid pfns where possible") optimized the loop in memmap_init_zone(). But there is still some room for improvement. E.g. if pfn and pfn+1 are in the same memblock region, we can simply pfn++ instead of doing the binary search in memblock_next_valid_pfn. Signed-off-by: Jia He <jia.he@...-semitech.com> --- arch/arm/include/asm/page.h | 1 + arch/arm/mm/init.c | 28 ++++++++++++++++++++++------ arch/arm64/include/asm/page.h | 1 + arch/arm64/mm/init.c | 28 ++++++++++++++++++++++------ 4 files changed, 46 insertions(+), 12 deletions(-) diff --git a/arch/arm/include/asm/page.h b/arch/arm/include/asm/page.h index 489875c..f38909c 100644 --- a/arch/arm/include/asm/page.h +++ b/arch/arm/include/asm/page.h @@ -157,6 +157,7 @@ extern void copy_page(void *to, const void *from); typedef struct page *pgtable_t; #ifdef CONFIG_HAVE_ARCH_PFN_VALID +extern int early_region_idx; extern int pfn_valid(unsigned long); extern unsigned long memblock_next_valid_pfn(unsigned long pfn); #define skip_to_last_invalid_pfn(pfn) (memblock_next_valid_pfn(pfn) - 1) diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c index 0fb85ca..06ed190 100644 --- a/arch/arm/mm/init.c +++ b/arch/arm/mm/init.c @@ -193,6 +193,8 @@ static void __init zone_sizes_init(unsigned long min, unsigned long max_low, } #ifdef CONFIG_HAVE_ARCH_PFN_VALID +int early_region_idx __meminitdata = -1; + int pfn_valid(unsigned long pfn) { return memblock_is_map_memory(__pfn_to_phys(pfn)); @@ -203,28 +205,42 @@ EXPORT_SYMBOL(pfn_valid); unsigned long __init_memblock memblock_next_valid_pfn(unsigned long pfn) { struct memblock_type *type = &memblock.memory; + struct memblock_region *regions = type->regions; unsigned int right = type->cnt; unsigned int mid, left = 0; + unsigned long start_pfn, end_pfn; phys_addr_t addr = PFN_PHYS(++pfn); + /* fast path, return pfn+1 if next pfn is in the same region */ + if (early_region_idx != -1) { + start_pfn = PFN_DOWN(regions[early_region_idx].base); + end_pfn = PFN_DOWN(regions[early_region_idx].base + + regions[early_region_idx].size); + + if (pfn >= start_pfn && pfn < end_pfn) + return pfn; + } + + /* slow path, do the binary searching */ do { mid = (right + left) / 2; - if (addr < type->regions[mid].base) + if (addr < regions[mid].base) right = mid; - else if (addr >= (type->regions[mid].base + - type->regions[mid].size)) + else if (addr >= (regions[mid].base + regions[mid].size)) left = mid + 1; else { - /* addr is within the region, so pfn is valid */ + early_region_idx = mid; return pfn; } } while (left < right); if (right == type->cnt) return -1UL; - else - return PHYS_PFN(type->regions[right].base); + + early_region_idx = right; + + return PHYS_PFN(regions[early_region_idx].base); } EXPORT_SYMBOL(memblock_next_valid_pfn); #endif /*CONFIG_HAVE_ARCH_PFN_VALID*/ diff --git a/arch/arm64/include/asm/page.h b/arch/arm64/include/asm/page.h index e57d3f2..f0d8c8e5 100644 --- a/arch/arm64/include/asm/page.h +++ b/arch/arm64/include/asm/page.h @@ -38,6 +38,7 @@ extern void clear_page(void *to); typedef struct page *pgtable_t; #ifdef CONFIG_HAVE_ARCH_PFN_VALID +extern int early_region_idx; extern int pfn_valid(unsigned long); extern unsigned long memblock_next_valid_pfn(unsigned long pfn); #define skip_to_last_invalid_pfn(pfn) (memblock_next_valid_pfn(pfn) - 1) diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c index 13e43ff..342e4e2 100644 --- a/arch/arm64/mm/init.c +++ b/arch/arm64/mm/init.c @@ -285,6 +285,8 @@ static void __init zone_sizes_init(unsigned long min, unsigned long max) #endif /* CONFIG_NUMA */ #ifdef CONFIG_HAVE_ARCH_PFN_VALID +int early_region_idx __meminitdata = -1; + int pfn_valid(unsigned long pfn) { return memblock_is_map_memory(pfn << PAGE_SHIFT); @@ -295,28 +297,42 @@ EXPORT_SYMBOL(pfn_valid); unsigned long __init_memblock memblock_next_valid_pfn(unsigned long pfn) { struct memblock_type *type = &memblock.memory; + struct memblock_region *regions = type->regions; unsigned int right = type->cnt; unsigned int mid, left = 0; + unsigned long start_pfn, end_pfn; phys_addr_t addr = PFN_PHYS(++pfn); + /* fast path, return pfn+1 if next pfn is in the same region */ + if (early_region_idx != -1) { + start_pfn = PFN_DOWN(regions[early_region_idx].base); + end_pfn = PFN_DOWN(regions[early_region_idx].base + + regions[early_region_idx].size); + + if (pfn >= start_pfn && pfn < end_pfn) + return pfn; + } + + /* slow path, do the binary searching */ do { mid = (right + left) / 2; - if (addr < type->regions[mid].base) + if (addr < regions[mid].base) right = mid; - else if (addr >= (type->regions[mid].base + - type->regions[mid].size)) + else if (addr >= (regions[mid].base + regions[mid].size)) left = mid + 1; else { - /* addr is within the region, so pfn is valid */ + early_region_idx = mid; return pfn; } } while (left < right); if (right == type->cnt) return -1UL; - else - return PHYS_PFN(type->regions[right].base); + + early_region_idx = right; + + return PHYS_PFN(regions[early_region_idx].base); } EXPORT_SYMBOL(memblock_next_valid_pfn); #endif /*CONFIG_HAVE_ARCH_PFN_VALID*/ -- 2.7.4
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