From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f41.google.com (mail-pa0-f41.google.com [209.85.220.41]) by kanga.kvack.org (Postfix) with ESMTP id 82FF46B0031 for ; Tue, 24 Sep 2013 09:21:14 -0400 (EDT) Received: by mail-pa0-f41.google.com with SMTP id bj1so4976213pad.14 for ; Tue, 24 Sep 2013 06:21:14 -0700 (PDT) Received: by mail-pb0-f44.google.com with SMTP id xa7so4564903pbc.3 for ; Tue, 24 Sep 2013 06:21:12 -0700 (PDT) Message-ID: <52419198.1010906@gmail.com> Date: Tue, 24 Sep 2013 21:20:24 +0800 From: Zhang Yanfei MIME-Version: 1.0 Subject: Re: [PATCH 3/6] x86/mm: Factor out of top-down direct mapping setup References: <524162DA.30004@cn.fujitsu.com> <52416431.1090107@cn.fujitsu.com> <20130924122712.GD2366@htj.dyndns.org> In-Reply-To: <20130924122712.GD2366@htj.dyndns.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Tejun Heo Cc: Zhang Yanfei , "Rafael J . Wysocki" , lenb@kernel.org, Thomas Gleixner , mingo@elte.hu, "H. Peter Anvin" , Andrew Morton , Toshi Kani , Wanpeng Li , Thomas Renninger , Yinghai Lu , Jiang Liu , Wen Congyang , Lai Jiangshan , isimatu.yasuaki@jp.fujitsu.com, izumi.taku@jp.fujitsu.com, Mel Gorman , Minchan Kim , mina86@mina86.com, gong.chen@linux.intel.com, vasilis.liaskovitis@profitbricks.com, lwoodman@redhat.com, Rik van Riel , jweiner@redhat.com, prarit@redhat.com, "x86@kernel.org" , linux-doc@vger.kernel.org, "linux-kernel@vger.kernel.org" , Linux MM , linux-acpi@vger.kernel.org, imtangchen@gmail.com Hello tejun, On 09/24/2013 08:27 PM, Tejun Heo wrote: > On Tue, Sep 24, 2013 at 06:06:41PM +0800, Zhang Yanfei wrote: >> +/** >> + * memory_map_top_down - Map [map_start, map_end) top down >> + * @map_start: start address of the target memory range >> + * @map_end: end address of the target memory range >> + * >> + * This function will setup direct mapping for memory range [map_start, map_end) >> + * in a heuristic way. In the beginning, step_size is small. The more memory we >> + * map memory in the next loop. >> + */ > > The comment reads a bit weird to me. The step size is increased > gradually but that really isn't really a heuristic and it doesn't > mention mapping direction. Ok, will change the words and add the comment of direction. > > ... >> @@ -430,19 +430,13 @@ void __init init_mem_mapping(void) >> min_pfn_mapped = real_end >> PAGE_SHIFT; >> last_start = start = real_end; >> >> - /* >> - * We start from the top (end of memory) and go to the bottom. >> - * The memblock_find_in_range() gets us a block of RAM from the >> - * end of RAM in [min_pfn_mapped, max_pfn_mapped) used as new pages >> - * for page table. >> - */ > > I think this comment should stay here with the variable names > updated. OK, agreed > >> - while (last_start > ISA_END_ADDRESS) { >> + while (last_start > map_start) { >> if (last_start > step_size) { >> start = round_down(last_start - 1, step_size); >> - if (start < ISA_END_ADDRESS) >> - start = ISA_END_ADDRESS; >> + if (start < map_start) >> + start = map_start; >> } else >> - start = ISA_END_ADDRESS; >> + start = map_start; >> new_mapped_ram_size = init_range_memory_mapping(start, >> last_start); >> last_start = start; >> @@ -453,8 +447,32 @@ void __init init_mem_mapping(void) >> mapped_ram_size += new_mapped_ram_size; >> } >> >> - if (real_end < end) >> - init_range_memory_mapping(real_end, end); >> + if (real_end < map_end) >> + init_range_memory_mapping(real_end, map_end); >> +} >> + >> +void __init init_mem_mapping(void) >> +{ >> + unsigned long end; >> + >> + probe_page_size_mask(); >> + >> +#ifdef CONFIG_X86_64 >> + end = max_pfn << PAGE_SHIFT; >> +#else >> + end = max_low_pfn << PAGE_SHIFT; >> +#endif >> + >> + /* the ISA range is always mapped regardless of memory holes */ >> + init_memory_mapping(0, ISA_END_ADDRESS); >> + >> + /* >> + * We start from the top (end of memory) and go to the bottom. >> + * The memblock_find_in_range() gets us a block of RAM from the >> + * end of RAM in [min_pfn_mapped, max_pfn_mapped) used as new pages >> + * for page table. >> + */ > > And just mention the range and direction in the comment here? OK, agreed. Thanks > >> + memory_map_top_down(ISA_END_ADDRESS, end); > > Thanks. > -- Thanks. Zhang Yanfei -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org