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=-17.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 0B803C49EAB for ; Mon, 28 Jun 2021 09:38:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E3EC861C51 for ; Mon, 28 Jun 2021 09:38:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232519AbhF1Jku (ORCPT ); Mon, 28 Jun 2021 05:40:50 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:35293 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232348AbhF1Jks (ORCPT ); Mon, 28 Jun 2021 05:40:48 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1624873099; h=from:from:reply-to: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; bh=KbstVO6yJsjAAz2Rw4pFG159iQgUyoPxnfRs5v5lilk=; b=ZqIAoS7zESNCpH8om+WBC9jRWVOJC4BKH0Q3u9CUp4c9m5LdVAr7vkMnBckFpX9nEAEaEN vN2fwKsgE1WmBuGzlS/j1ozxZ1ZC1nadxeT9vpz0iFl28hTKQUvc5WI7y4SlIWGITuu1lW YtF8kIJzkEn5WpuVphYH54pWodO+3B0= 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-424-XZYQWhsCMlauT0z5wfc2VA-1; Mon, 28 Jun 2021 05:38:17 -0400 X-MC-Unique: XZYQWhsCMlauT0z5wfc2VA-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 79ADE802E62; Mon, 28 Jun 2021 09:38:16 +0000 (UTC) Received: from [10.64.54.204] (vpn2-54-204.bne.redhat.com [10.64.54.204]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 0CE705B826; Mon, 28 Jun 2021 09:38:13 +0000 (UTC) Reply-To: Gavin Shan Subject: Re: [PATCH v4] Documentation, dt, numa: Add note to empty NUMA node To: Andrew Jones Cc: devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, rdunlap@infradead.org, robh+dt@kernel.org, shan.gavin@gmail.com References: <20210625052338.4875-1-gshan@redhat.com> <20210625070217.4ffmfe7nwlusbbjc@gator> <20210625070656.j373hveemf5cdch4@gator> <41643136-798b-a0f3-aee7-b6af94a2fc67@redhat.com> <20210625101821.3t3vgj2pnw3hqpzm@gator> <62d04903-e4f3-2302-d530-5942e33ae116@redhat.com> <20210628083420.v47xbbtcgjj2mu47@gator> From: Gavin Shan Message-ID: <60a2b930-40cc-ea32-878f-d063523b5fec@redhat.com> Date: Mon, 28 Jun 2021 19:38:11 +1000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.0 MIME-Version: 1.0 In-Reply-To: <20210628083420.v47xbbtcgjj2mu47@gator> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 6/28/21 6:34 PM, Andrew Jones wrote: > On Fri, Jun 25, 2021 at 09:14:49PM +1000, Gavin Shan wrote: >> On 6/25/21 8:18 PM, Andrew Jones wrote: >>> On Fri, Jun 25, 2021 at 06:36:48PM +1000, Gavin Shan wrote: >>>> On 6/25/21 5:06 PM, Andrew Jones wrote: >>>>> On Fri, Jun 25, 2021 at 09:02:17AM +0200, Andrew Jones wrote: >>>>>> On Fri, Jun 25, 2021 at 01:23:38PM +0800, Gavin Shan wrote: >>>>>>> The empty memory nodes, where no memory resides in, are allowed. >>>>>>> For these empty memory nodes, the 'len' of 'reg' property is zero. >>>>>>> The NUMA node IDs are still valid and parsed, but memory can be >>>>>>> added to them through hotplug afterwards. I finds difficulty to >>>>>>> get where it's properly documented. >>>>>>> >>>>>>> So lets add note to empty memory nodes in the NUMA binding doc. >>>>>>> >>>>>>> Signed-off-by: Gavin Shan >>>>>>> --- >>>>>>> Documentation/devicetree/bindings/numa.txt | 4 ++++ >>>>>>> 1 file changed, 4 insertions(+) >>>>>>> >>>>>>> diff --git a/Documentation/devicetree/bindings/numa.txt b/Documentation/devicetree/bindings/numa.txt >>>>>>> index 21b35053ca5a..0fc882e44270 100644 >>>>>>> --- a/Documentation/devicetree/bindings/numa.txt >>>>>>> +++ b/Documentation/devicetree/bindings/numa.txt >>>>>>> @@ -109,6 +109,10 @@ Example: >>>>>>> Dual socket system consists of 2 boards connected through ccn bus and >>>>>>> each board having one socket/soc of 8 cpus, memory and pci bus. >>>>>>> +Note that empty memory nodes, which no memory resides in, are allowed. >>>>>>> +The NUMA node IDs in these empty memory nodes are still valid, but >>>>>>> +memory can be added into them through hotplug afterwards. >>>>>> >>>>>> Please change the second sentence to: >>>>>> >>>>>> The NUMA node IDs in these empty memory nodes are still valid and >>>>>> memory may be added into them through hotplug afterwards. >>>>>> >>>>>> But, this doesn't look like the right place for this paragraph. You're >>>>>> adding the paragraph to the example section, but the example doesn't have >>>>>> any empty memory nodes. >>>>>> >>>>>> I think the paragraph should be added to section "2 - numa-node-id" and an >>>>> >>>>> Or maybe even create a new section for it. >>>>> >>>>>> example empty memory node should be provided. Also, the commit message >>>>>> talks about the length of 'reg' being zero, which is an important >>>>>> distinction which should also be documented. >>>>>> >>>> >>>> Drew, thanks for your comments. Yeah, it sounds sensible to create >>>> a new section for it and an example would be more helpful. Please >>>> check if below changes are fine to you. I probably need Randy's review >>>> again. >>>> >>>> I'm trying to avoid too many revisions for this sort of trivial patch, >>>> even though I already had. However, it's time frame for v5.14 and I'm >>>> pushing this to be merged during the cycle. >>> >>> We must revise until we're satisfied... Also, I wouldn't call writing >>> specifications trivial. >>> >> >> [...] >> >>> I'll just rewrite it: >>> >>> Empty memory nodes, which no memory resides in, are allowed. The 'length' >>> field of the 'reg' property is zero, but the 'base-address' is a dummy >>> address and invalid. However, the NUMA node IDs and distance maps are >>> still valid and memory may be added into them through hotplug afterwards. >>> >> >> [...] >> >>> >>> You should write how you've selected the dummy addresses for the empty >>> memory nodes, perhaps here in the /* Empty memory node */ comments or >>> above in the paragraph or both. >>> >>>> + memory@0x100000000 { >>>> + device_type = "memory"; >>>> + reg = <0x1 0x0 0x0 0x0>; >>>> + numa-node-id = <2>; >>>> + }; >>>> + >>>> + /* Empty memory node */ >>>> + memory@0x180000000 { >>>> + device_type = "memory"; >>>> + reg = <0x1 0x80000000 0x0 0x0>; >>>> + numa-node-id = <3>; >>>> + }; >>>> + >> >> [...] >> >> Thanks, Drew. As 'base-address' is dummy address and invalid. So we >> would note it as suggestion. With your suggestion integrated, how about >> something like this? >> >> ============================================================================== >> 4 - Empty memory nodes >> ============================================================================== >> >> Empty memory nodes, which no memory resides in, are allowed. The 'length' >> field of the 'reg' property is zero, but the 'base-address' is a dummy >> address and invalid. The 'base-address' could be the summation of highest >> memory address plus the NUMA node ID. However, the NUMA node IDs and >> distance maps are still valid and memory may be added into them through >> hotplug afterwards. >> >> : >> >> memory@0 { >> device_type = "memory"; >> reg = <0x0 0x0 0x0 0x80000000>; >> numa-node-id = <0>; >> }; >> >> memory@0x80000000 { >> device_type = "memory"; >> reg = <0x0 0x80000000 0x0 0x80000000>; >> numa-node-id = <1>; >> }; >> >> /* Empty memory node */ >> memory@0x100000002 { >> device_type = "memory"; >> reg = <0x1 0x2 0x0 0x0>; >> numa-node-id = <2>; >> }; >> >> /* Empty memory node */ >> memory@0x100000003 { >> device_type = "memory"; >> reg = <0x1 0x3 0x0 0x0>; >> numa-node-id = <3>; >> }; >> >> : >> >> Thanks, >> Gavin >> >> > > Looks good to me. > Thanks, Drew. v5 was posted to reflect changes, but I don't include Randy's r-b because too much changes introduced. Hopefully, Randy can take a look on v5 when getting a chance. Thanks, Gavin