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=-3.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 82BDAC433DB for ; Wed, 17 Feb 2021 21:32:11 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 1A0826186A for ; Wed, 17 Feb 2021 21:32:11 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1A0826186A Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 989886B0006; Wed, 17 Feb 2021 16:32:10 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 8EB236B006C; Wed, 17 Feb 2021 16:32:10 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 7DCCB6B006E; Wed, 17 Feb 2021 16:32:10 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0254.hostedemail.com [216.40.44.254]) by kanga.kvack.org (Postfix) with ESMTP id 640CF6B0006 for ; Wed, 17 Feb 2021 16:32:10 -0500 (EST) Received: from smtpin21.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 26326184B1FE9 for ; Wed, 17 Feb 2021 21:32:10 +0000 (UTC) X-FDA: 77829058020.21.3F7EB26 Received: from mail-pg1-f172.google.com (mail-pg1-f172.google.com [209.85.215.172]) by imf09.hostedemail.com (Postfix) with ESMTP id F09A36002496 for ; Wed, 17 Feb 2021 21:32:06 +0000 (UTC) Received: by mail-pg1-f172.google.com with SMTP id m2so9330281pgq.5 for ; Wed, 17 Feb 2021 13:32:09 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=q5lpJnSfMK2r040N1CTw4nW5Tu3iCtr8TbUrRfyRBDw=; b=XYyy4U5xgETcDbter4ThfNo1nWOwUyn5Zka4yGJXnczgDxpu8OzC2SeQfO652VBz7b PhM7QTV1nG24H/7zGkXgEEhj/sHZrIFSN4mAbV2dY9SLWPJlGs19V6yFIlVlLuIKi0+g wvGTrsrkHtC2g/q+Soxs3lXAbEaXYrcKABklOK2ADvRnTMSyDsCEP5mJ84z2Gz/3/f1F Fe2+uauF3lqBsuqdWiy8H7XsjDQf5z+wsYjgoxt6tRWBNpz1CM2ORMfGHl7tcI2WcR16 SFybEEpwND09gVKNl0Tg/ZnbK0DCh62p7azXT5Yb8Q9Uce5XFRBkrgSOcggkaNrjK/FH nHKQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to; bh=q5lpJnSfMK2r040N1CTw4nW5Tu3iCtr8TbUrRfyRBDw=; b=o8WGthpCedaKa28s6N2WujTFxbsZMd6iKaKhzTjmlFB1h79VLvwx4syf4RMQmS/Ab8 FwZjpCvP4jZAnft+Utb61GqsyIJ5NVSvxXmGfFfpBMIhVuPbLoTvoXTLnB/5bj9+ocVP SJlzdoyX7OVRs4ouvi4Pa2x+0a6CXF1ZT0x+7OL6RdvaJ6siM6LMaQnf6esxM8UY0LfA lzefJ7ycBcl+gRWgG4emnm0DYsPjnyrxaXyJjndWkDRH4+zILD0ZCNvpKDONj4MO5CZi bev303gA0lJmbY5UNDXTZ2GqaMDG6kXHsY4KtXXFcxRTlMM8qwfwx6uAwkrQ/9SWsZ/y 9dAA== X-Gm-Message-State: AOAM532MR8UPBHMVa5pLJUZcS0U7XaMcWnhzbZ5M4rgq9zFe7Y/+C2Qo hoLAX1Irp2psvSzL3HpPtCVFIraj+ko= X-Google-Smtp-Source: ABdhPJysKKbh3uXsS1n47LDBCg2iETu9A7l0d8w0U7tJONzrFie6igTVAhyGJBI9zbY82LKAKpN9zA== X-Received: by 2002:a65:4082:: with SMTP id t2mr1174216pgp.140.1613597528714; Wed, 17 Feb 2021 13:32:08 -0800 (PST) Received: from google.com ([2620:15c:211:201:157d:8a19:5427:ea9e]) by smtp.gmail.com with ESMTPSA id bj9sm3132679pjb.49.2021.02.17.13.32.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 17 Feb 2021 13:32:07 -0800 (PST) Date: Wed, 17 Feb 2021 13:32:05 -0800 From: Minchan Kim To: Matthew Wilcox Cc: Michal Hocko , Andrew Morton , linux-mm , LKML , cgoldswo@codeaurora.org, linux-fsdevel@vger.kernel.org, david@redhat.com, vbabka@suse.cz, viro@zeniv.linux.org.uk, joaodias@google.com Subject: Re: [RFC 1/2] mm: disable LRU pagevec during the migration temporarily Message-ID: References: <20210216170348.1513483-1-minchan@kernel.org> <20210217211612.GO2858050@casper.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210217211612.GO2858050@casper.infradead.org> X-Stat-Signature: xhpw6u4f48temfordkzt3jxyswermoro X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: F09A36002496 Received-SPF: none (gmail.com>: No applicable sender policy available) receiver=imf09; identity=mailfrom; envelope-from=""; helo=mail-pg1-f172.google.com; client-ip=209.85.215.172 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1613597526-235814 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 Wed, Feb 17, 2021 at 09:16:12PM +0000, Matthew Wilcox wrote: > On Wed, Feb 17, 2021 at 12:46:19PM -0800, Minchan Kim wrote: > > > I suspect you do not want to add atomic_read inside hot paths, right? Is > > > this really something that we have to microoptimize for? atomic_read is > > > a simple READ_ONCE on many archs. > > > > It's also spin_lock_irq_save in some arch. If the new synchonization is > > heavily compilcated, atomic would be better for simple start but I thought > > this locking scheme is too simple so no need to add atomic operation in > > readside. > > What arch uses a spinlock for atomic_read()? I just had a quick grep and > didn't see any. Ah, my bad. I was confused with update side. Okay, let's use atomic op to make it simple. Thanks for the review, Mattew and Michal.