From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ob0-f170.google.com (mail-ob0-f170.google.com [209.85.214.170]) by kanga.kvack.org (Postfix) with ESMTP id 3A7266B0005 for ; Mon, 15 Feb 2016 05:07:56 -0500 (EST) Received: by mail-ob0-f170.google.com with SMTP id wb13so205916207obb.1 for ; Mon, 15 Feb 2016 02:07:56 -0800 (PST) Received: from szxga02-in.huawei.com (szxga02-in.huawei.com. [119.145.14.65]) by mx.google.com with ESMTPS id j79si16172575oib.97.2016.02.15.02.07.54 for (version=TLS1 cipher=AES128-SHA bits=128/128); Mon, 15 Feb 2016 02:07:55 -0800 (PST) Message-ID: <56C1A310.9090305@huawei.com> Date: Mon, 15 Feb 2016 18:06:08 +0800 From: Xishi Qiu MIME-Version: 1.0 Subject: Re: [PATCH v2 3/3] mm/compaction: speed up pageblock_pfn_to_page() when zone is contiguous References: <1454566775-30973-1-git-send-email-iamjoonsoo.kim@lge.com> <1454566775-30973-3-git-send-email-iamjoonsoo.kim@lge.com> <20160204164929.a2f12b8a7edcdfa596abd850@linux-foundation.org> <56C0550F.8020402@huawei.com> <20160215024220.GA30918@js1304-P5Q-DELUXE> In-Reply-To: <20160215024220.GA30918@js1304-P5Q-DELUXE> Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Joonsoo Kim Cc: zhong jiang , Andrew Morton , Vlastimil Babka , Aaron Lu , Mel Gorman , Rik van Riel , David Rientjes , LKML , Linux Memory Management List On 2016/2/15 10:42, Joonsoo Kim wrote: >> >> I have a question about the zone continuity. because hole exists at >> arbitrary position in a page block. Therefore, only pageblock_pf_to_page() >> is insufficiency, whether pageblock aligned pfn or not , the pfn_valid_within() >> is necessary. >> >> eh: 120M-122M is a range of page block, but the 120.5M-121.5M is holes, only by >> pageblock_pfn_to_page() to conclude in the result is inaccurate > > contiguous may be misleading word. It doesn't represent there are no > hole. It only represents that all pageblocks within zone span belong to > corresponding zone and validity of all pageblock aligned pfn is > checked. So, if it is set, we can safely call pfn_to_page() for pageblock > aligned pfn in that zone without checking pfn_valid(). > > Thanks. > Hi Joonsoo, So "contiguous" here only means that struct page is exist, and don't care whether the memory is exist, right? Thanks, Xishi Qiu > > . > -- 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