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 X-Spam-Level: X-Spam-Status: No, score=-0.9 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,UNPARSEABLE_RELAY autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5A956C04A6B for ; Fri, 10 May 2019 16:50:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3752921479 for ; Fri, 10 May 2019 16:50:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727974AbfEJQuQ (ORCPT ); Fri, 10 May 2019 12:50:16 -0400 Received: from out30-43.freemail.mail.aliyun.com ([115.124.30.43]:45002 "EHLO out30-43.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727838AbfEJQuP (ORCPT ); Fri, 10 May 2019 12:50:15 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R151e4;CH=green;DM=||false|;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01f04446;MF=yang.shi@linux.alibaba.com;NM=1;PH=DS;RN=10;SR=0;TI=SMTPD_---0TRMJzjz_1557507007; Received: from US-143344MP.local(mailfrom:yang.shi@linux.alibaba.com fp:SMTPD_---0TRMJzjz_1557507007) by smtp.aliyun-inc.com(127.0.0.1); Sat, 11 May 2019 00:50:10 +0800 Subject: Re: [PATCH] mm: vmscan: correct nr_reclaimed for THP To: Matthew Wilcox , "Huang, Ying" Cc: hannes@cmpxchg.org, mhocko@suse.com, mgorman@techsingularity.net, kirill.shutemov@linux.intel.com, hughd@google.com, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <1557447392-61607-1-git-send-email-yang.shi@linux.alibaba.com> <87y33fjbvr.fsf@yhuang-dev.intel.com> <20190510163612.GA23417@bombadil.infradead.org> From: Yang Shi Message-ID: <3a919cba-fefe-d78e-313a-8f0d81a4a75d@linux.alibaba.com> Date: Fri, 10 May 2019 09:50:04 -0700 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.12; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 MIME-Version: 1.0 In-Reply-To: <20190510163612.GA23417@bombadil.infradead.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 5/10/19 9:36 AM, Matthew Wilcox wrote: > On Fri, May 10, 2019 at 10:12:40AM +0800, Huang, Ying wrote: >>> + nr_reclaimed += (1 << compound_order(page)); >> How about to change this to >> >> >> nr_reclaimed += hpage_nr_pages(page); > Please don't. That embeds the knowledge that we can only swap out either > normal pages or THP sized pages. I'm trying to make the VM capable of > supporting arbitrary-order pages, and this would be just one more place > to fix. > > I'm sympathetic to the "self documenting" argument. My current tree has > a patch in it: > > mm: Introduce compound_nr > > Replace 1 << compound_order(page) with compound_nr(page). Minor > improvements in readability. > > It goes along with this patch: > > mm: Introduce page_size() > > It's unnecessarily hard to find out the size of a potentially huge page. > Replace 'PAGE_SIZE << compound_order(page)' with page_size(page). So you prefer keeping using  "1 << compound_order" as v1 did? Then you will convert all "1 << compound_order" to compound_nr? > > Better suggestions on naming gratefully received. I'm more happy with > page_size() than I am with compound_nr(). page_nr() gives the wrong > impression; page_count() isn't great either.