From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-io0-f200.google.com (mail-io0-f200.google.com [209.85.223.200]) by kanga.kvack.org (Postfix) with ESMTP id 146336B0003 for ; Thu, 29 Mar 2018 04:06:58 -0400 (EDT) Received: by mail-io0-f200.google.com with SMTP id w197so4529800iod.23 for ; Thu, 29 Mar 2018 01:06:58 -0700 (PDT) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id o34sor2564393ioi.141.2018.03.29.01.06.56 for (Google Transport Security); Thu, 29 Mar 2018 01:06:56 -0700 (PDT) Subject: Re: [PATCH v3 2/5] mm: page_alloc: reduce unnecessary binary search in memblock_next_valid_pfn() References: <1522033340-6575-1-git-send-email-hejianet@gmail.com> <1522033340-6575-3-git-send-email-hejianet@gmail.com> <20180328092620.GA98648@WeideMacBook-Pro.local> From: Jia He Message-ID: <2c41a24b-1fa6-7115-c312-a11157619a16@gmail.com> Date: Thu, 29 Mar 2018 16:06:38 +0800 MIME-Version: 1.0 In-Reply-To: <20180328092620.GA98648@WeideMacBook-Pro.local> Content-Type: text/plain; charset=gbk; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Wei Yang Cc: Andrew Morton , Michal Hocko , Catalin Marinas , Mel Gorman , Will Deacon , Mark Rutland , Ard Biesheuvel , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , 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 On 3/28/2018 5:26 PM, Wei Yang Wrote: > On Sun, Mar 25, 2018 at 08:02:16PM -0700, Jia He wrote: >> 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 */ > ^^^ pfn Thanks >> + if (*last_idx != -1) { >> + start_pfn = PFN_DOWN(type->regions[*last_idx].base); > To me, it should be PFN_UP(). hmm.., seems all the base of memory region is pfn aligned (0x10000 aligned). So PFN_UP is the same as PFN_DOWN here? I got this logic from memblock_search_pfn_nid() Cheers, Jia > >> + end_pfn = PFN_DOWN(type->regions[*last_idx].base + >> + type->regions[*last_idx].size); >> + >> + if (pfn < end_pfn && pfn > start_pfn) > Could be (pfn < end_pfn && pfn >= start_pfn)? > > pfn == start_pfn is also a valid address. No, pfn=pfn+1 at the beginning, so 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*/ > The same comment as Daniel, you are moving the function out of > CONFIG_HAVE_MEMBLOCK_NODE_MAP. >> + >> 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