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Peter Anvin" Cc: Pavel Tatashin , Daniel Jordan , AKASHI Takahiro , Gioh Kim , Steven Sistare , Daniel Vacek , Eugeniu Rosca , Vlastimil Babka , linux-kernel@vger.kernel.org, linux-mm@kvack.org, James Morse , Steve Capper , x86@kernel.org, Greg Kroah-Hartman , Kate Stewart , Philippe Ombredanne , Johannes Weiner , Kemi Wang , Petr Tesarik , YASUAKI ISHIMATSU , Andrey Ryabinin , Nikolay Borisov , Jia He , Jia He Subject: [PATCH v3 2/5] mm: page_alloc: reduce unnecessary binary search in memblock_next_valid_pfn() Date: Sun, 25 Mar 2018 20:02:16 -0700 Message-Id: <1522033340-6575-3-git-send-email-hejianet@gmail.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1522033340-6575-1-git-send-email-hejianet@gmail.com> References: <1522033340-6575-1-git-send-email-hejianet@gmail.com> X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1595967686923865256?= X-GMAIL-MSGID: =?utf-8?q?1595967686923865256?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 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. This patch only works when CONFIG_HAVE_ARCH_PFN_VALID is enable. Signed-off-by: Jia He --- include/linux/memblock.h | 2 +- mm/memblock.c | 73 +++++++++++++++++++++++++++++------------------- mm/page_alloc.c | 3 +- 3 files changed, 47 insertions(+), 31 deletions(-) diff --git a/include/linux/memblock.h b/include/linux/memblock.h index efbbe4b..a8fb2ab 100644 --- a/include/linux/memblock.h +++ b/include/linux/memblock.h @@ -204,7 +204,7 @@ void __next_mem_pfn_range(int *idx, int nid, unsigned long *out_start_pfn, #endif /* CONFIG_HAVE_MEMBLOCK_NODE_MAP */ #ifdef CONFIG_HAVE_ARCH_PFN_VALID -unsigned long memblock_next_valid_pfn(unsigned long pfn); +unsigned long memblock_next_valid_pfn(unsigned long pfn, int *idx); #endif /** diff --git a/mm/memblock.c b/mm/memblock.c index bea5a9c..06c1a08 100644 --- a/mm/memblock.c +++ b/mm/memblock.c @@ -1102,35 +1102,6 @@ void __init_memblock __next_mem_pfn_range(int *idx, int nid, *out_nid = r->nid; } -#ifdef CONFIG_HAVE_ARCH_PFN_VALID -unsigned long __init_memblock memblock_next_valid_pfn(unsigned long pfn) -{ - struct memblock_type *type = &memblock.memory; - unsigned int right = type->cnt; - unsigned int mid, left = 0; - phys_addr_t addr = PFN_PHYS(++pfn); - - do { - mid = (right + left) / 2; - - if (addr < type->regions[mid].base) - right = mid; - else if (addr >= (type->regions[mid].base + - type->regions[mid].size)) - left = mid + 1; - else { - /* addr is within the region, so pfn is valid */ - return pfn; - } - } while (left < right); - - if (right == type->cnt) - return -1UL; - else - return PHYS_PFN(type->regions[right].base); -} -#endif /*CONFIG_HAVE_ARCH_PFN_VALID*/ - /** * memblock_set_node - set node ID on memblock regions * @base: base of area to set node ID for @@ -1162,6 +1133,50 @@ int __init_memblock memblock_set_node(phys_addr_t base, phys_addr_t size, } #endif /* CONFIG_HAVE_MEMBLOCK_NODE_MAP */ +#ifdef CONFIG_HAVE_ARCH_PFN_VALID +unsigned long __init_memblock memblock_next_valid_pfn(unsigned long pfn, + int *last_idx) +{ + struct memblock_type *type = &memblock.memory; + 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 pfh+1 if next pfn is in the same region */ + if (*last_idx != -1) { + start_pfn = PFN_DOWN(type->regions[*last_idx].base); + end_pfn = PFN_DOWN(type->regions[*last_idx].base + + type->regions[*last_idx].size); + + if (pfn < end_pfn && pfn > start_pfn) + return pfn; + } + + /* slow path, do the binary searching */ + do { + mid = (right + left) / 2; + + if (addr < type->regions[mid].base) + right = mid; + else if (addr >= (type->regions[mid].base + + type->regions[mid].size)) + left = mid + 1; + else { + *last_idx = mid; + return pfn; + } + } while (left < right); + + if (right == type->cnt) + return -1UL; + + *last_idx = right; + + return PHYS_PFN(type->regions[*last_idx].base); +} +#endif /*CONFIG_HAVE_ARCH_PFN_VALID*/ + static phys_addr_t __init memblock_alloc_range_nid(phys_addr_t size, phys_addr_t align, phys_addr_t start, phys_addr_t end, int nid, ulong flags) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 2a967f7..0bb0274 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -5459,6 +5459,7 @@ void __meminit memmap_init_zone(unsigned long size, int nid, unsigned long zone, unsigned long end_pfn = start_pfn + size; pg_data_t *pgdat = NODE_DATA(nid); unsigned long pfn; + int idx = -1; unsigned long nr_initialised = 0; struct page *page; #ifdef CONFIG_HAVE_MEMBLOCK_NODE_MAP @@ -5490,7 +5491,7 @@ void __meminit memmap_init_zone(unsigned long size, int nid, unsigned long zone, * end_pfn), such that we hit a valid pfn (or end_pfn) * on our next iteration of the loop. */ - pfn = memblock_next_valid_pfn(pfn) - 1; + pfn = memblock_next_valid_pfn(pfn, &idx) - 1; #endif continue; } -- 2.7.4