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=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,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 BD9F9C5ACD7 for ; Wed, 18 Mar 2020 13:50:26 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 5B16E20776 for ; Wed, 18 Mar 2020 13:50:26 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="TY8IPwcC" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5B16E20776 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id B7FF46B0006; Wed, 18 Mar 2020 09:50:25 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id B31E26B0007; Wed, 18 Mar 2020 09:50:25 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 9F9126B000A; Wed, 18 Mar 2020 09:50:25 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0111.hostedemail.com [216.40.44.111]) by kanga.kvack.org (Postfix) with ESMTP id 84CEF6B0006 for ; Wed, 18 Mar 2020 09:50:25 -0400 (EDT) Received: from smtpin25.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 45AE1181AEF1A for ; Wed, 18 Mar 2020 13:50:25 +0000 (UTC) X-FDA: 76608617610.25.paste31_3dd235998ae3c X-HE-Tag: paste31_3dd235998ae3c X-Filterd-Recvd-Size: 8710 Received: from us-smtp-delivery-74.mimecast.com (us-smtp-delivery-74.mimecast.com [63.128.21.74]) by imf25.hostedemail.com (Postfix) with ESMTP for ; Wed, 18 Mar 2020 13:50:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1584539424; h=from:from: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:autocrypt:autocrypt; bh=gXZwvmBo8DHFVt6LhIa/MMBfh0m6YycvZpBWNrfzRaY=; b=TY8IPwcC7nD6K/lxwj7NNFeIfvbcuWmgmewB0vJuZBjPMxT7RF6e59IZINXDKZZY6Z+qdY 9cMXCm07F1H4M5qiCAw2l64zgK2mtwJfk667H8bncsgC9l2IjAUpGnMjyFP01k3Poxmioc GPjlwvELQ2/F3Qu3VT0F8XZ9f3tm/64= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-292-Gw8ViglfPhSkSGPwrex7pw-1; Wed, 18 Mar 2020 09:50:22 -0400 X-MC-Unique: Gw8ViglfPhSkSGPwrex7pw-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id B6728800D5A; Wed, 18 Mar 2020 13:50:17 +0000 (UTC) Received: from [10.36.114.65] (ovpn-114-65.ams2.redhat.com [10.36.114.65]) by smtp.corp.redhat.com (Postfix) with ESMTP id 9584160BF1; Wed, 18 Mar 2020 13:50:12 +0000 (UTC) Subject: Re: [PATCH v2 0/8] mm/memory_hotplug: allow to specify a default online_type To: Baoquan He Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, linux-hyperv@vger.kernel.org, Vitaly Kuznetsov , Yumei Huang , Igor Mammedov , Eduardo Habkost , Milan Zamazal , Andrew Morton , Benjamin Herrenschmidt , Greg Kroah-Hartman , Haiyang Zhang , "K. Y. Srinivasan" , Michael Ellerman , Michal Hocko , Michal Hocko , Oscar Salvador , Paul Mackerras , "Rafael J. Wysocki" , Stephen Hemminger , Wei Liu , Wei Yang References: <20200317104942.11178-1-david@redhat.com> <20200318130517.GC30899@MiWiFi-R3L-srv> From: David Hildenbrand Autocrypt: addr=david@redhat.com; prefer-encrypt=mutual; keydata= mQINBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABtCREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT6JAlgEEwEIAEICGwMFCQlmAYAGCwkIBwMCBhUI AgkKCwQWAgMBAh4BAheAFiEEG9nKrXNcTDpGDfzKTd4Q9wD/g1oFAl3pImkCGQEACgkQTd4Q 9wD/g1o+VA//SFvIHUAvul05u6wKv/pIR6aICPdpF9EIgEU448g+7FfDgQwcEny1pbEzAmiw zAXIQ9H0NZh96lcq+yDLtONnXk/bEYWHHUA014A1wqcYNRY8RvY1+eVHb0uu0KYQoXkzvu+s Dncuguk470XPnscL27hs8PgOP6QjG4jt75K2LfZ0eAqTOUCZTJxA8A7E9+XTYuU0hs7QVrWJ jQdFxQbRMrYz7uP8KmTK9/Cnvqehgl4EzyRaZppshruKMeyheBgvgJd5On1wWq4ZUV5PFM4x II3QbD3EJfWbaJMR55jI9dMFa+vK7MFz3rhWOkEx/QR959lfdRSTXdxs8V3zDvChcmRVGN8U Vo93d1YNtWnA9w6oCW1dnDZ4kgQZZSBIjp6iHcA08apzh7DPi08jL7M9UQByeYGr8KuR4i6e RZI6xhlZerUScVzn35ONwOC91VdYiQgjemiVLq1WDDZ3B7DIzUZ4RQTOaIWdtXBWb8zWakt/ ztGhsx0e39Gvt3391O1PgcA7ilhvqrBPemJrlb9xSPPRbaNAW39P8ws/UJnzSJqnHMVxbRZC Am4add/SM+OCP0w3xYss1jy9T+XdZa0lhUvJfLy7tNcjVG/sxkBXOaSC24MFPuwnoC9WvCVQ ZBxouph3kqc4Dt5X1EeXVLeba+466P1fe1rC8MbcwDkoUo65Ag0EVcufkQEQAOfX3n0g0fZz Bgm/S2zF/kxQKCEKP8ID+Vz8sy2GpDvveBq4H2Y34XWsT1zLJdvqPI4af4ZSMxuerWjXbVWb T6d4odQIG0fKx4F8NccDqbgHeZRNajXeeJ3R7gAzvWvQNLz4piHrO/B4tf8svmRBL0ZB5P5A 2uhdwLU3NZuK22zpNn4is87BPWF8HhY0L5fafgDMOqnf4guJVJPYNPhUFzXUbPqOKOkL8ojk CXxkOFHAbjstSK5Ca3fKquY3rdX3DNo+EL7FvAiw1mUtS+5GeYE+RMnDCsVFm/C7kY8c2d0G NWkB9pJM5+mnIoFNxy7YBcldYATVeOHoY4LyaUWNnAvFYWp08dHWfZo9WCiJMuTfgtH9tc75 7QanMVdPt6fDK8UUXIBLQ2TWr/sQKE9xtFuEmoQGlE1l6bGaDnnMLcYu+Asp3kDT0w4zYGsx 5r6XQVRH4+5N6eHZiaeYtFOujp5n+pjBaQK7wUUjDilPQ5QMzIuCL4YjVoylWiBNknvQWBXS lQCWmavOT9sttGQXdPCC5ynI+1ymZC1ORZKANLnRAb0NH/UCzcsstw2TAkFnMEbo9Zu9w7Kv AxBQXWeXhJI9XQssfrf4Gusdqx8nPEpfOqCtbbwJMATbHyqLt7/oz/5deGuwxgb65pWIzufa N7eop7uh+6bezi+rugUI+w6DABEBAAGJAiUEGAECAA8FAlXLn5ECGwwFCQlmAYAACgkQTd4Q 9wD/g1qA6w/+M+ggFv+JdVsz5+ZIc6MSyGUozASX+bmIuPeIecc9UsFRatc91LuJCKMkD9Uv GOcWSeFpLrSGRQ1Z7EMzFVU//qVs6uzhsNk0RYMyS0B6oloW3FpyQ+zOVylFWQCzoyyf227y GW8HnXunJSC+4PtlL2AY4yZjAVAPLK2l6mhgClVXTQ/S7cBoTQKP+jvVJOoYkpnFxWE9pn4t H5QIFk7Ip8TKr5k3fXVWk4lnUi9MTF/5L/mWqdyIO1s7cjharQCstfWCzWrVeVctpVoDfJWp 4LwTuQ5yEM2KcPeElLg5fR7WB2zH97oI6/Ko2DlovmfQqXh9xWozQt0iGy5tWzh6I0JrlcxJ ileZWLccC4XKD1037Hy2FLAjzfoWgwBLA6ULu0exOOdIa58H4PsXtkFPrUF980EEibUp0zFz GotRVekFAceUaRvAj7dh76cToeZkfsjAvBVb4COXuhgX6N4pofgNkW2AtgYu1nUsPAo+NftU CxrhjHtLn4QEBpkbErnXQyMjHpIatlYGutVMS91XTQXYydCh5crMPs7hYVsvnmGHIaB9ZMfB njnuI31KBiLUks+paRkHQlFcgS2N3gkRBzH7xSZ+t7Re3jvXdXEzKBbQ+dC3lpJB0wPnyMcX FOTT3aZT7IgePkt5iC/BKBk3hqKteTnJFeVIT7EC+a6YUFg= Organization: Red Hat GmbH Message-ID: <67a054f6-df07-e4fb-dd4b-e503cb767276@redhat.com> Date: Wed, 18 Mar 2020 14:50:11 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 MIME-Version: 1.0 In-Reply-To: <20200318130517.GC30899@MiWiFi-R3L-srv> Content-Type: text/plain; charset=utf-8 Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Content-Transfer-Encoding: quoted-printable 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 18.03.20 14:05, Baoquan He wrote: > On 03/17/20 at 11:49am, David Hildenbrand wrote: >> Distributions nowadays use udev rules ([1] [2]) to specify if and >> how to online hotplugged memory. The rules seem to get more complex wi= th >> many special cases. Due to the various special cases, >> CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE cannot be used. All memory hotplu= g >> is handled via udev rules. >> >> Everytime we hotplug memory, the udev rule will come to the same >> conclusion. Especially Hyper-V (but also soon virtio-mem) add a lot of >> memory in separate memory blocks and wait for memory to get onlined by= user >> space before continuing to add more memory blocks (to not add memory f= aster >> than it is getting onlined). This of course slows down the whole memor= y >> hotplug process. >> >> To make the job of distributions easier and to avoid udev rules that g= et >> more and more complicated, let's extend the mechanism provided by >> - /sys/devices/system/memory/auto_online_blocks >> - "memhp_default_state=3D" on the kernel cmdline >> to be able to specify also "online_movable" as well as "online_kernel" >=20 > This patch series looks good, thanks. Since Andrew has merged it to -mm= again, > I won't add my Reviewed-by to bother.=20 >=20 > Hi David, Vitaly >=20 > There are several things unclear to me. >=20 > So, these improved interfaces are used to alleviate the burden of the=20 > existing udev rules, or try to replace it? As you know, we have been At least in RHEL, my plan is to replace it / use a udev rules as a fallback on older kernels (see the example scripts below). But other distribution can handle it as they want. > using udev rules to interact between kernel and user space on bare meta= l, > and guests who want to hot add/remove.> > And also the OOM issue in hyperV when onlining pages after adding memor= y > block. I am not a virt devel expert, could this happen on bare metal > system? Don't think it's relevant on bare metal. If you plug a big DIMM, all memory blocks will be added first in one shot and then all memory blocks will be onlined. So it doesn't matter "how fast" you online that memory. In contrast, Hyper-V (and virtio-mem) add one (or a limited number of) memory block at a time and wait for them to get onlined. --=20 Thanks, David / dhildenb