From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4EBBEC6FA8F for ; Wed, 30 Aug 2023 07:02:42 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id BFB58280029; Wed, 30 Aug 2023 03:02:41 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id BAB588E0009; Wed, 30 Aug 2023 03:02:41 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A7293280029; Wed, 30 Aug 2023 03:02:41 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id 947C18E0009 for ; Wed, 30 Aug 2023 03:02:41 -0400 (EDT) Received: from smtpin15.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 66EBD120291 for ; Wed, 30 Aug 2023 07:02:41 +0000 (UTC) X-FDA: 81179878122.15.F335A0C Received: from dggsgout12.his.huawei.com (unknown [45.249.212.56]) by imf17.hostedemail.com (Postfix) with ESMTP id 41A8B40013 for ; Wed, 30 Aug 2023 07:02:33 +0000 (UTC) Authentication-Results: imf17.hostedemail.com; dkim=none; dmarc=none; spf=none (imf17.hostedemail.com: domain of shikemeng@huaweicloud.com has no SPF policy when checking 45.249.212.56) smtp.mailfrom=shikemeng@huaweicloud.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1693378955; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=BJzdk6I8mel4m9j4nHw8TBABiYfkpA2UeiDtdWyUfBA=; b=wOQZF9xAXwwqO+5gqjUOU+GEOfDzQ38AB90DJQlGHU5d3M+h44FK9kOV/N6P2Q0DBvjb92 rMFNqidr2LLWFyCWVmJg4IlDmSN9UM4WBQJAGk4cMMeMGf5JDuYLHfJFe9aCQmP6+Zhug4 N4jMtQihWTGJCCbEoZd4NNEv3XXGnC8= ARC-Authentication-Results: i=1; imf17.hostedemail.com; dkim=none; dmarc=none; spf=none (imf17.hostedemail.com: domain of shikemeng@huaweicloud.com has no SPF policy when checking 45.249.212.56) smtp.mailfrom=shikemeng@huaweicloud.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1693378955; a=rsa-sha256; cv=none; b=fxIqZfUATGHP8TPwSWfyq55XBTeosdHycqQSwB39/IXZDvvIN4i03I6MX7riQhqjkbOTmR g6wMoJeovz1GrnsGlRqyJ1478yXKUvifhjZV5l+QprZ1AmWIQeHp8s48RxPEX36kuy18rr lMVugI9HLaRludtcfi73bqTs6/BApEA= Received: from mail02.huawei.com (unknown [172.30.67.153]) by dggsgout12.his.huawei.com (SkyGuard) with ESMTP id 4RbFbY3bLBz4f3jJC for ; Wed, 30 Aug 2023 15:02:17 +0800 (CST) Received: from [10.174.178.129] (unknown [10.174.178.129]) by APP1 (Coremail) with SMTP id cCh0CgAnnip76e5kzm5HBw--.65103S2; Wed, 30 Aug 2023 15:02:21 +0800 (CST) Subject: Re: [PATCH v2 4/7] mm/compaction: simplify pfn iteration in isolate_freepages_range To: Mel Gorman Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, baolin.wang@linux.alibaba.com, david@redhat.com, willy@infradead.org References: <20230826153617.4019189-1-shikemeng@huaweicloud.com> <20230826153617.4019189-5-shikemeng@huaweicloud.com> <20230829150153.j4lw36s7yx5be7al@techsingularity.net> From: Kemeng Shi Message-ID: Date: Wed, 30 Aug 2023 15:02:19 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.5.0 MIME-Version: 1.0 In-Reply-To: <20230829150153.j4lw36s7yx5be7al@techsingularity.net> Content-Type: text/plain; charset=iso-8859-15 Content-Transfer-Encoding: 7bit X-CM-TRANSID:cCh0CgAnnip76e5kzm5HBw--.65103S2 X-Coremail-Antispam: 1UD129KBjvJXoW7uryUKw4Utr4kZr1rtrW7twb_yoW8Ww4xpa y5Ga1I9r1kGayUWFnxAw1DZ3WrK39IvF47XrW5Xr1fX395Xa4xZF93Ar4YkFyxtrnrCr1q vrZFgrZ2q3WDXa7anT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUkjb4IE77IF4wAFF20E14v26r4j6ryUM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28lY4IEw2IIxxk0rwA2F7IY1VAKz4 vEj48ve4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_Xr0_Ar1l84ACjcxK6xIIjxv20xvEc7Cj xVAFwI0_Cr0_Gr1UM28EF7xvwVC2z280aVAFwI0_GcCE3s1l84ACjcxK6I8E87Iv6xkF7I 0E14v26rxl6s0DM2AIxVAIcxkEcVAq07x20xvEncxIr21l5I8CrVACY4xI64kE6c02F40E x7xfMcIj6xIIjxv20xvE14v26r106r15McIj6I8E87Iv67AKxVWUJVW8JwAm72CE4IkC6x 0Yz7v_Jr0_Gr1lF7xvr2IY64vIr41lc7I2V7IY0VAS07AlzVAYIcxG8wCF04k20xvY0x0E wIxGrwCFx2IqxVCFs4IE7xkEbVWUJVW8JwC20s026c02F40E14v26r1j6r18MI8I3I0E74 80Y4vE14v26r106r1rMI8E67AF67kF1VAFwI0_JF0_Jw1lIxkGc2Ij64vIr41lIxAIcVC0 I7IYx2IY67AKxVWUJVWUCwCI42IY6xIIjxv20xvEc7CjxVAFwI0_Gr0_Cr1lIxAIcVCF04 k26cxKx2IYs7xG6rWUJVWrZr1UMIIF0xvEx4A2jsIE14v26r1j6r4UMIIF0xvEx4A2jsIE c7CjxVAFwI0_Gr0_Gr1UYxBIdaVFxhVjvjDU0xZFpf9x07UQzVbUUUUU= X-CM-SenderInfo: 5vklyvpphqwq5kxd4v5lfo033gof0z/ X-CFilter-Loop: Reflected X-Rspamd-Queue-Id: 41A8B40013 X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: xd6g71fpiy8skyshnykcy7bor1he75b3 X-HE-Tag: 1693378953-196198 X-HE-Meta: U2FsdGVkX1/5+gXGuJDSX+/p8cyS8eTBKVhrlRP9ICb+wOeGzaW5Yr4mNuMwg/T1s1CNsnw1N/IDoHWqSyceSETV6l7XYuBQcp5K2brC40AFNuBZkT8K3sqtfSkGqm+DHPAJKkN0iofHPJni+SlR3B1Lv7QMAENKYmL3ekd/hejuKDvEIwLMSYldLCfrcMjamx5NVtjcDQQxkpmr74HxgHqcjzQ1BV+CK5rPHA9b+xAVZLaYvBFyWyo46K6QquUVszW35TtjUEmzhWKnEVjy0sHG3RNoRxxe1uGaFEi6UBWNjK3OLQ1YBfioNlMNmGJmVf1BdhULxfoYgp3jXwjpLhCNrkjPMcy0WgawJ9YFGaDPAQW8xGhccbUJeJLiuCQAp5WT2b/mCi1z07p8NFzZCYytBa61YQgnUsLE/Tx/D+Aox9jL5t4Qec7gfzPgptoYB54jePobKwG8QqL37VVlD2KiWu7a4Kqlken7pT934EwGcwDXPmgiFhM6oDcVvtIMRsHAf7IVt61BjQNK9zWYoz3xfnKSlqPhb3/AGwfrXOInUOgGYLD3cZC8zfB+tkNSXKm1WF3vh662VhjazKUT2J1Uqa/1N1dw/PyzvXplGM3Y5CBZnwD5luG79+icD5Y1fpnZ4gov/cxZObl/USpRJ4K5vtQeHpT7RXk3kaqKHVmKebGBBcowroxjj4vrKLgGJt3wH+BotNUufkOD4gLd/U7Of1UjiC95QvYPWdaaMQM/9LR7nCFTRbVaQUEBRklz97OOS8RSSrq58on3SUWNlYlAAyNQn+jJMpE7cZy7wI+q11TDknD1nd/9xiqygCttQcLbiRkOqd64PNeENak5lqFx9Zlu19dLsKKnsOijv60Li0s7k1VuTsl8xMaB/x2NNXA6I3bk6SreOBN3Be2qHtL3RdMpEsv0/za96Oh7HgOVajisrevSy8YwL5obC9amNKzE1qCnnn0G3RomB4r irjdH+jR +i815J979ddFsO7R9UG91XjMeS8LWrtdEat0fq23VW7W4oOFOmyx6AlRs4ikgLh8aC8AA3OoU8agVlGQYfuQNEp6xU2RaEgzn5P1AbNqJOB/uPinhsblweOffVuCD4a+ab/qwEY8Wt1mUIZBPFhkRJcT9AMdNs5apsNC7TDnf0fgAGOtCQoQ7W9qAWpzLoWUuWbFwuYdgk7jPtXY69HyiglWTomvhXt++F7UNfcXMm3L8ZJQ/jk/s9yYjGX+K58g0gdf2c6HNyPJvz/1dzFPuTntLspCdheA9O1ZJcL3eNF6jLciwxeaN6/eAzQ== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: on 8/29/2023 11:01 PM, Mel Gorman wrote: > On Sat, Aug 26, 2023 at 11:36:14PM +0800, Kemeng Shi wrote: >> We call isolate_freepages_block in strict mode, continuous pages in >> pageblock will be isolated if isolate_freepages_block successed. >> Then pfn + isolated will point to start of next pageblock to scan >> no matter how many pageblocks are isolated in isolate_freepages_block. >> Use pfn + isolated as start of next pageblock to scan to simplify the >> iteration. >> >> The pfn + isolated always points to start of next pageblock as: >> In case isolated buddy page has order higher than pageblock: >> 1. page in buddy page is aligned with it's order >> 2. order of page is higher than pageblock order >> Then page is aligned with pageblock order. So pfn of page and isolated >> pages count are both aligned pageblock order. So pfn + isolated is >> pageblock order aligned. >> >> In case isolated buddy page has order lower than pageblock: >> Buddy page with order N contains two order N - 1 pages as following: >> | order N | >> |order N - 1|order N - 1| >> So buddy pages with order N - 1 will never cross boudary of order N. >> Similar, buddy pages with order N - 2 will never cross boudary of order >> N - 1 and so on. Then any pages with order less than pageblock order >> will never crosa boudary of pageblock. >> >> Signed-off-by: Kemeng Shi >> Reviewed-by: Baolin Wang > > While I don't think the patch is wrong, I also don't think it > meaningfully simplifies the code or optimises enough to be justified. > Even though a branch is eliminated, the whole path is not cheap. > OK, I will drop this in next version if you insistant.