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=-2.5 required=3.0 tests=MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 BEDD4C32751 for ; Wed, 31 Jul 2019 14:37:17 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 8B1772089E for ; Wed, 31 Jul 2019 14:37:17 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8B1772089E 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 313828E0005; Wed, 31 Jul 2019 10:37:17 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 2C39C8E0001; Wed, 31 Jul 2019 10:37:17 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 18C2D8E0005; Wed, 31 Jul 2019 10:37:17 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from mail-ed1-f70.google.com (mail-ed1-f70.google.com [209.85.208.70]) by kanga.kvack.org (Postfix) with ESMTP id C10FE8E0001 for ; Wed, 31 Jul 2019 10:37:16 -0400 (EDT) Received: by mail-ed1-f70.google.com with SMTP id y24so42603673edb.1 for ; Wed, 31 Jul 2019 07:37:16 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-original-authentication-results:x-gm-message-state:date:from:to :cc:subject:message-id:references:mime-version:content-disposition :in-reply-to:user-agent; bh=So2BqeAhYIGhnn9/LcBQ8ANJy/L5YQB8n4YH5s7LXo0=; b=pVj5rxqbADg3G5mJ7VSI6DmW6OKwSPTytjedz++CkFkdfwMOCjfGmjvm8R30lLzLD4 IJ3f/5yPUnNJd57LlpCdC/6AV4fkc5527gFkYqMbn9vZekRYr9bslFe/Fe2ic9Opyd3c BHQcGdlQxmjnOeeUqE45uEDjGYS8pBREK5QLX+8ONYRxViirczT1zlFYQyuh0h67XpvS xTwZK1HE+ZWlO3S9Rl/Vo35+Vy+dc3Exd1HE+5eJHfL6132rxXPff/DER4Ksrsl9+tVG L9lChksUUdbBS9kDf4Xh9t2M0pCo+b2JxQprYrRlwOyZormjIf+N5VJrBVTOqh8c7MQr RruA== X-Original-Authentication-Results: mx.google.com; spf=softfail (google.com: domain of transitioning mhocko@kernel.org does not designate 195.135.220.15 as permitted sender) smtp.mailfrom=mhocko@kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=kernel.org X-Gm-Message-State: APjAAAXRWBvLvDSFOyT6SzF8Y1Ht+2bsYgOVVTTW2MbSa85OehCsNMpB lPfmkkae+eKrMdzVjuyNsoAUfY3QDYfd2oEze/nXCq72gYL+7DlWW3BfuXeEqvJHo76Kd04ggSC k3ciQ/lWT3VX8tbumcnRpja26zgayTfNArjZuwXOlOVKFU1D++LlE6fc5JsFBgME= X-Received: by 2002:a50:9822:: with SMTP id g31mr104798705edb.175.1564583836342; Wed, 31 Jul 2019 07:37:16 -0700 (PDT) X-Google-Smtp-Source: APXvYqzY3yBMPSiZCAbwoiCwLRwa0YEIG2qD3KZ+su3IkzjfrotwGrggKODt+2SI2kVRWXzlTt2q X-Received: by 2002:a50:9822:: with SMTP id g31mr104798608edb.175.1564583835428; Wed, 31 Jul 2019 07:37:15 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1564583835; cv=none; d=google.com; s=arc-20160816; b=SUBYUAWpccim1NzvjhDxGXReEwhV3sIFkYK/McANNVXQLbmGxqanjIwV32toqn7bip Nvym/+phLYXdF8UIqgf4ofKcqScPVIyxaklcLyOzZU0yoaCLRIs0nwMtuucLdvC0uuKi iynrPlUVZHcDIeYnEjsqcEWgGYtL8w8fX+Q/BaCu1YBvksPswehnDMY1uOTLBsdX1RSn pFqWdPD/c1AQwfBUInjpjgic8X1pGt10POnnVBc3MVXH1aMMxIMc1rWVGhYmSjUksjl8 g16nyD/8uWWV3Hi4ts/mQIum/TCP7vjOuFy6KuqyPQoQfXE5Po/DgSiaL0xN8PQqsE5t rQHA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=user-agent:in-reply-to:content-disposition:mime-version:references :message-id:subject:cc:to:from:date; bh=So2BqeAhYIGhnn9/LcBQ8ANJy/L5YQB8n4YH5s7LXo0=; b=IJx8d19L3IHTz5VEXDNOS28/KZBg0yLL51E0/UwVQaxRxMolrdefIkMFrskXndvRJ/ nVuvV7ldYBpsUIrYeHcAeke/KyL9PxabqreSZtYIMPPsz/OkplcTiWojxmECtqXYtQMk E9w/dD2ZFuheZ1d5O7gWVbTpG2ctRUOIl8qwPQ16H193wLnYiPfABHuA+JSG1KbxpIj4 evG9v0yfAlrFJXwqqNBoRlTOFaYA/haWGkpowGUfa3YAdrxPe7Rxh2hDR3Q2tSYVyn3w qUcUFkSpKyXHzOqHGF+Qtn8fK5GR+FOqDXzw1LKip+g9umdlUeOlEbar+yjshquWgolQ o+pw== ARC-Authentication-Results: i=1; mx.google.com; spf=softfail (google.com: domain of transitioning mhocko@kernel.org does not designate 195.135.220.15 as permitted sender) smtp.mailfrom=mhocko@kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: from mx1.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id x15si18314058ejv.41.2019.07.31.07.37.15 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 31 Jul 2019 07:37:15 -0700 (PDT) Received-SPF: softfail (google.com: domain of transitioning mhocko@kernel.org does not designate 195.135.220.15 as permitted sender) client-ip=195.135.220.15; Authentication-Results: mx.google.com; spf=softfail (google.com: domain of transitioning mhocko@kernel.org does not designate 195.135.220.15 as permitted sender) smtp.mailfrom=mhocko@kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=kernel.org X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id E5D3EAC9A; Wed, 31 Jul 2019 14:37:14 +0000 (UTC) Date: Wed, 31 Jul 2019 16:37:14 +0200 From: Michal Hocko To: David Hildenbrand Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Greg Kroah-Hartman , "Rafael J. Wysocki" , Andrew Morton , Pavel Tatashin , Dan Williams , Oscar Salvador Subject: Re: [PATCH v1] drivers/base/memory.c: Don't store end_section_nr in memory blocks Message-ID: <20190731143714.GX9330@dhcp22.suse.cz> References: <20190731122213.13392-1-david@redhat.com> <20190731124356.GL9330@dhcp22.suse.cz> <20190731132534.GQ9330@dhcp22.suse.cz> <58bd9479-051b-a13b-b6d0-c93aac2ed1b3@redhat.com> <20190731141411.GU9330@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) 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 31-07-19 16:21:46, David Hildenbrand wrote: [...] > > Thinking about it some more, I believe that we can reasonably provide > > both APIs controlable by a command line parameter for backwards > > compatibility. It is the hotplug code to control sysfs APIs. E.g. > > create one sysfs entry per add_memory_resource for the new semantic. > > Yeah, but the real question is: who needs it. I can only think about > some DIMM scenarios (some, not all). I would be interested in more use > cases. Of course, to provide and maintain two APIs we need a good reason. Well, my 3TB machine that has 7 movable nodes could really go with less than $ find /sys/devices/system/memory -name "memory*" | wc -l 1729 when it doesn't really make any sense to offline less than a hotremovable entity which is the whole node effectivelly. I have seen reports where a similarly large machine chocked on boot just because of too many udev events... In other words allowing smaller granularity is a nice toy but real usecases usually work with the whole hotplugable entity (e.g. the whole ACPI container). > (one sysfs per add_memory_resource() won't cover all DIMMs completely as > far as I remember - I might be wrong, I remember there could be a > sequence of add_memory(). Also, some DIMMs might actually overlap with > memory indicated during boot - complicated stuff) Which is something we have to live with anyway due to nodes interleaving. So nothing really new. -- Michal Hocko SUSE Labs