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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 05903C433F5 for ; Wed, 10 Nov 2021 06:19:12 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 8611D61107 for ; Wed, 10 Nov 2021 06:19:11 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 8611D61107 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=bytedance.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id 147FB6B006C; Wed, 10 Nov 2021 01:19:11 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 0F9106B0071; Wed, 10 Nov 2021 01:19:11 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id F01C46B0072; Wed, 10 Nov 2021 01:19:10 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0038.hostedemail.com [216.40.44.38]) by kanga.kvack.org (Postfix) with ESMTP id E02516B006C for ; Wed, 10 Nov 2021 01:19:10 -0500 (EST) Received: from smtpin28.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 98AF17F910 for ; Wed, 10 Nov 2021 06:19:10 +0000 (UTC) X-FDA: 78792018060.28.5D9E700 Received: from mail-yb1-f171.google.com (mail-yb1-f171.google.com [209.85.219.171]) by imf25.hostedemail.com (Postfix) with ESMTP id 5857EB000198 for ; Wed, 10 Nov 2021 06:18:56 +0000 (UTC) Received: by mail-yb1-f171.google.com with SMTP id v7so3895841ybq.0 for ; Tue, 09 Nov 2021 22:19:07 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20210112.gappssmtp.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=IjUT8zCp2aLFMQgSGnAyzSy9afXTEGUeSUT1uAZ7PO8=; b=v9Y/NbJGrZHSlykl99QODQr2L+E6A/yXZBeBI6qkRCLgq3bsOIp2K86NV5/7A2MCWO W5iIvM32RREMYIexhAKSHaabulV+5QCary78yorn8Bdqf/JV/KR5nDVwXmrIkMnAVJtp lJb5H2+JwqrgqysOJXa7oZtiNWZmz+3weCON1t/D7ptQpsGxFYpL1nPfmAevqYrLpxGX B3tzSoNjBm/UbNWh6Z44JTfXa4c8SsYCIcb8hnczY++B5QoKj2palcQ+u+q4n/PuU/I7 /hcmU920o2jq57EE9RKaBfIgnHI3xyRpsZf/mzDfVAj45qDsEup1eaHpm648d/IJ+diT 7eKA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=IjUT8zCp2aLFMQgSGnAyzSy9afXTEGUeSUT1uAZ7PO8=; b=rKVmkUiiw6AZFaLSUcGqo23oPBlfUmuZ+O8QtK7qbUzLC8r1RDBpCe/RotIRAiqB3Q mCy9GKNb2W0xh53X2F/D8bVykiTH/Ojtip00AR/plnrOc+A3Nv6Ke8GqbOKpub5MgMCH xl6XZepqaNzu/pnfyI92dR6L74nmJpVp26pUqoiFKR8HsQsx4LuSQgZUF+UyRBfFLwIe VfSmugeymHssi+TKVOqN4e9sDDUEh4DYVGKUyeFTfuVNT4t+R/anQu4O7KCiyK2o+sf+ ocITZ8iF0G5KJ8A0bwSkOyHKWkMR15gZJ0bEWA7MkcqiNc8PsweQ1L+zN8YxVkFTqxr+ cxJw== X-Gm-Message-State: AOAM533uhN11X4izTs7Ei7U5kYK2PVP7093XHObT3boZNYQyDyBvxszp 5qUQd+AB8zTx5aC3y9lnO73nFDjwMdkc4YzohjNu8w== X-Google-Smtp-Source: ABdhPJyohPEpBCsDPpumT7620p3FFrCbW0oBZn8eKqR9DCKf+/LwgW+c7aCl7L981TDd4Nbz5zjOd52C8OBlwTDibwo= X-Received: by 2002:a25:ef0b:: with SMTP id g11mr14790116ybd.404.1636525146779; Tue, 09 Nov 2021 22:19:06 -0800 (PST) MIME-Version: 1.0 References: <20211101031651.75851-1-songmuchun@bytedance.com> <35c5217d-eb8f-6f70-544a-a3e8bd009a46@oracle.com> In-Reply-To: <35c5217d-eb8f-6f70-544a-a3e8bd009a46@oracle.com> From: Muchun Song Date: Wed, 10 Nov 2021 14:18:28 +0800 Message-ID: Subject: Re: [PATCH v7 0/5] Free the 2nd vmemmap page associated with each HugeTLB page To: Mike Kravetz Cc: Andrew Morton , Oscar Salvador , Michal Hocko , David Hildenbrand , Jonathan Corbet , Matthew Wilcox , Xiongchun duan , fam.zheng@bytedance.com, Muchun Song , Qi Zheng , linux-doc@vger.kernel.org, LKML , Linux Memory Management List , "Song Bao Hua (Barry Song)" , Barry Song <21cnbao@gmail.com>, Chen Huang , "Bodeddula, Balasubramaniam" Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 5857EB000198 X-Stat-Signature: p4i1uzetxje8xksa19ty9fgqw1wuxekq Authentication-Results: imf25.hostedemail.com; dkim=pass header.d=bytedance-com.20210112.gappssmtp.com header.s=20210112 header.b="v9Y/NbJG"; dmarc=pass (policy=none) header.from=bytedance.com; spf=pass (imf25.hostedemail.com: domain of songmuchun@bytedance.com designates 209.85.219.171 as permitted sender) smtp.mailfrom=songmuchun@bytedance.com X-HE-Tag: 1636525136-994491 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 Tue, Nov 9, 2021 at 3:33 AM Mike Kravetz wrote: > > On 11/8/21 12:16 AM, Muchun Song wrote: > > On Mon, Nov 1, 2021 at 11:22 AM Muchun Song wrote: > >> > >> This series can minimize the overhead of struct page for 2MB HugeTLB pages > >> significantly. It further reduces the overhead of struct page by 12.5% for > >> a 2MB HugeTLB compared to the previous approach, which means 2GB per 1TB > >> HugeTLB. It is a nice gain. Comments and reviews are welcome. Thanks. > >> > > > > Hi, > > > > Ping guys. Does anyone have any comments or suggestions > > on this series? > > > > Thanks. > > > > I did look over the series earlier. I have no issue with the hugetlb and > vmemmap modifications as they are enhancements to the existing > optimizations. My primary concern is the (small) increased overhead > for the helpers as outlined in your cover letter. Since these helpers > are not limited to hugetlb and used throughout the kernel, I would > really like to get comments from others with a better understanding of > the potential impact. Thanks Mike. I'd like to hear others' comments about this as well. >From my point of view, maybe the (small) overhead is acceptable since it only affects the head page, however Matthew Wilcox's folio series could reduce this situation as well. Looking forward to others' comments. Thanks. > > -- > Mike Kravetz