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=-5.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 237C6C35247 for ; Thu, 6 Feb 2020 00:37:50 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id CC8942082E for ; Thu, 6 Feb 2020 00:37:49 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="BDmKe+3q" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CC8942082E 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 5F8866B0003; Wed, 5 Feb 2020 19:37:49 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 5A8D66B0006; Wed, 5 Feb 2020 19:37:49 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 4E6756B0007; Wed, 5 Feb 2020 19:37:49 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0064.hostedemail.com [216.40.44.64]) by kanga.kvack.org (Postfix) with ESMTP id 378D36B0003 for ; Wed, 5 Feb 2020 19:37:49 -0500 (EST) Received: from smtpin27.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id ED3BD180AD804 for ; Thu, 6 Feb 2020 00:37:48 +0000 (UTC) X-FDA: 76457839416.27.pipe07_44304e81b7a4d X-HE-Tag: pipe07_44304e81b7a4d X-Filterd-Recvd-Size: 5593 Received: from us-smtp-1.mimecast.com (us-smtp-delivery-1.mimecast.com [207.211.31.120]) by imf47.hostedemail.com (Postfix) with ESMTP for ; Thu, 6 Feb 2020 00:37:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1580949468; 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: in-reply-to:in-reply-to:references:references; bh=8Z6nE63gkylXxznMu19+y8UaaSgJhxKrGIJf/yXmjUY=; b=BDmKe+3qGBwa3hnRvSSeVlTDycXwKtIadDuZWOpimaQzKvndThSp6H5pHKqDuoR24CjlqU JitoUmFJRd3+M4Vc6P0DTGAv95ipDOWLFjU3ZsAOcIk3H/90PUhFT2v531xOhdiBYovhUA ZpQJRhbJ44zeBkSJNSRoVcrkWiK00eU= 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-219-fQOd-l-lNTSkXVrIatLn2g-1; Wed, 05 Feb 2020 19:37:44 -0500 X-MC-Unique: fQOd-l-lNTSkXVrIatLn2g-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 935B11005513; Thu, 6 Feb 2020 00:37:42 +0000 (UTC) Received: from localhost (ovpn-12-19.pek2.redhat.com [10.72.12.19]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 77E9D60BF7; Thu, 6 Feb 2020 00:37:39 +0000 (UTC) Date: Thu, 6 Feb 2020 08:37:36 +0800 From: Baoquan He To: Wei Yang Cc: David Hildenbrand , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Segher Boessenkool , Andrew Morton , Michal Hocko , Oscar Salvador Subject: Re: [PATCH v1] mm/memory_hotplug: Easier calculation to get pages to next section boundary Message-ID: <20200206003736.GI8965@MiWiFi-R3L-srv> References: <20200205135251.37488-1-david@redhat.com> <20200205231945.GB28446@richard> <20200205235007.GA28870@richard> <20200206001317.GH8965@MiWiFi-R3L-srv> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200206001317.GH8965@MiWiFi-R3L-srv> User-Agent: Mutt/1.10.1 (2018-07-13) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 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 02/06/20 at 08:13am, Baoquan He wrote: > On 02/06/20 at 07:50am, Wei Yang wrote: > > On Thu, Feb 06, 2020 at 07:19:45AM +0800, Wei Yang wrote: > > >On Wed, Feb 05, 2020 at 02:52:51PM +0100, David Hildenbrand wrote: > > >>Let's use a calculation that's easier to understand and calculates the > > >>same result. Reusing existing macros makes this look nicer. > > >> > > >>We always want to have the number of pages (> 0) to the next section > > >>boundary, starting from the current pfn. > > >> > > >>Suggested-by: Segher Boessenkool > > >>Cc: Andrew Morton > > >>Cc: Michal Hocko > > >>Cc: Oscar Salvador > > >>Cc: Baoquan He > > >>Cc: Wei Yang > > >>Signed-off-by: David Hildenbrand > > > > > >Reviewed-by: Wei Yang > > > > > >BTW, I got one question about hotplug size requirement. > > > > > >I thought the hotplug range should be section size aligned, while taking a > > >look into current code function check_hotplug_memory_range() guard the range. > > A good question. The current code should be block size aligned. I > remember in some places we assume each block comprise all the sections. > Can't imagine one or some of them are half section filled. I could be wrong, half filled block may not cause problem. > > It truly has a risk that system ram is very huge to make the block > size is 2G, someone try to insert a 1G memory board. However, it should > only exist in experiment environment, e.g build a guest with enough ram, > then hot add 1G DIMM. In reality, we don't need to worry about it, at > least what I saw is 512G order of magnitude. > > > > > > >This function says the range should be block_size aligned. And if I am > > >correct, block size on x86 should be in the range > > > > > > [MIN_MEMORY_BLOCK_SIZE, MEM_SIZE_FOR_LARGE_BLOCK] > > > > > >And MIN_MEMORY_BLOCK_SIZE is section size. > > No, if I got it right, the range on x86 is > [MIN_MEMORY_BLOCK_SIZE, MAX_BLOCK_SIZE]. > > MEM_SIZE_FOR_LARGE_BLOCK is the starting point from which block size can > be adjusted. Otherwise it's MIN_MEMORY_BLOCK_SIZE. > > /* Amount of ram needed to start using large blocks */ > #define MEM_SIZE_FOR_LARGE_BLOCK (64UL << 30) > > > > > > >Seems currently we support subsection hotplug? Then how a subsection range got > > >hotplug? Or this patch is a pre-requisite? > > The sub-section hotplug feature was added by your colleague Dan > Williams. It intends to fix a nvdimms issue that nvdimms device could be > mapped into a non section size aligned starting address. And nvdimms > makes use of the existing memory hotplug mechanism to manage pages. > Not sure if we are saying the same thing. > > > > > > > > One more question is we support hot-add subsection memory but not support > > hot-online subsection memory. > > > > Is my understanding correct? > > > > -- > > Wei Yang > > Help you, Help me > >