Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
From:   "Zi Yan" <ziy@nvidia.com>
To:     "David Hildenbrand" <david@redhat.com>
Cc:     "Oscar Salvador" <osalvador@suse.de>,
        "Michael Ellerman" <mpe@ellerman.id.au>,
        "Benjamin Herrenschmidt" <benh@kernel.crashing.org>,
        "Thomas Gleixner" <tglx@linutronix.de>, x86@kernel.org,
        "Andy Lutomirski" <luto@kernel.org>,
        "Rafael J . Wysocki" <rafael@kernel.org>,
        "Andrew Morton" <akpm@linux-foundation.org>,
        "Mike Rapoport" <rppt@kernel.org>,
        "Anshuman Khandual" <anshuman.khandual@arm.com>,
        "Michal Hocko" <mhocko@suse.com>,
        "Dan Williams" <dan.j.williams@intel.com>,
        "Wei Yang" <richard.weiyang@linux.alibaba.com>,
        linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org,
        linuxppc-dev@lists.ozlabs.org, linux-mm@kvack.org
Subject: Re: [RFC PATCH 0/7] Memory hotplug/hotremove at subsection size
Date:   Thu, 06 May 2021 11:50:08 -0400
Message-ID: <16962E62-7D1E-4E06-B832-EC91F54CC359@nvidia.com>
In-Reply-To: <3a51f564-f3d1-c21f-93b5-1b91639523ec@redhat.com>
References: <20210506152623.178731-1-zi.yan@sent.com>
 <fb60eabd-f8ef-2cb1-7338-7725efe3c286@redhat.com>
 <9D7FD316-988E-4B11-AC1C-64FF790BA79E@nvidia.com>
 <3a51f564-f3d1-c21f-93b5-1b91639523ec@redhat.com>
Content-Type: multipart/signed;
 boundary="=_MailMate_EF181C5B-F560-456C-BCA4-7AD984E499FD_=";
 micalg=pgp-sha512; protocol="application/pgp-signature"
MIME-Version: 1.0
X-MS-Exchange-MessageSentRepresentingType: 1
Received: from [10.2.63.7] (216.228.112.22) by MN2PR05CA0059.namprd05.prod.outlook.com (2603:10b6:208:236::28) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4129.11 via Frontend Transport; Thu, 6 May 2021 15:50:10 +0000
X-MS-PublicTrafficType: Email
X-MS-Office365-Filtering-Correlation-Id: 4a2db97e-f624-4c48-62e7-08d910a6a382
X-MS-TrafficTypeDiagnostic: BL0PR12MB2468:
X-MS-Exchange-Transport-Forked: True
X-Microsoft-Antispam-PRVS: <BL0PR12MB2468B754CC1E5FE3B1B1021AC2589@BL0PR12MB2468.namprd12.prod.outlook.com>
X-MS-Oob-TLC-OOBClassifiers: OLM:9508;
X-MS-Exchange-SenderADCheck: 1
X-Microsoft-Antispam: BCL:0;
X-Microsoft-Antispam-Message-Info: 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
X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:MN2PR12MB3823.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(4636009)(39860400002)(346002)(376002)(366004)(136003)(396003)(66946007)(235185007)(33656002)(8936002)(66476007)(2906002)(186003)(16526019)(66556008)(6916009)(956004)(2616005)(5660300002)(4326008)(8676002)(26005)(16576012)(7416002)(36756003)(478600001)(316002)(6486002)(53546011)(83380400001)(54906003)(38100700002)(33964004)(86362001)(72826003)(45980500001);DIR:OUT;SFP:1101;
X-MS-Exchange-AntiSpam-MessageData: =?utf-8?B?amN6YUpLNkIyRXdJNmFSRmVPVkdFVGdqcWd5eGlUVVlNTUg4NDdXUnlMdEFT?=
 =?utf-8?B?U3NYNWdER1gxdkt6R2ZHR3daamU5SlRIQkFsTFRFYS84V0tHWFpHVzJhVjRi?=
 =?utf-8?B?bGIxZ2YvNVFZemV3QUJGN2oxLzdxM2E2aEpDd1o4eWRGb09MUXdkaGU2bjR3?=
 =?utf-8?B?eVZPUFpIN1NDS1RIY0k5OXlZSENIMGNwQW1nWjhxNEpnekVTVXU3WFVVVXRx?=
 =?utf-8?B?UVZHOG5vUzFYbUI0VGc2YjVRTW50M2t2emlITHpkVkgwY3JqTGljckhOWkl0?=
 =?utf-8?B?YmJrT01uTms0L01BWldNOTNxSFdjYzAvRldNSlZBQ0tWT3VPNWtINk1XTUxG?=
 =?utf-8?B?L3JXU1RtQUFOcG1IbjcvclppdXJFS2VKazRyaG9RMDc5OUJIc1BLaHBDbEw1?=
 =?utf-8?B?aStUWEFKVDlTdUR6TEk4SndmV0l4MU1BM2dqdmZHU2RqOXhNdTQvNWxya1p3?=
 =?utf-8?B?QkhBRW8xMzJFOVA5bWF5akJTTjFwTVppQngxRHdXNDkwbWN3NC9IQVhPaUZk?=
 =?utf-8?B?U2JjWHVhazRvdldpbjEwd2hrdWYrQVB1R1AwR1lkWUs4YU5rN3htdDFJZGRz?=
 =?utf-8?B?QUljdFhUVmRwRWgzU1M3RFhCNTIzVEtoaG5PbUYyRUlQZWZHZlBzT3ZtMGQ2?=
 =?utf-8?B?UlloYzV5czU2N0c4aWpsUjkzNGxwMnE4STlWS0tIYVlRMS9LR2xSY0w4MU1h?=
 =?utf-8?B?a3F1WmRwT0hBLzBxT0xnNmJJSjJBQldlRWRCcG9ZdTE3bWJTTHJ0bEwyMzFF?=
 =?utf-8?B?dlM2TzRtZ3FJRWtnNDhiMFgvaG5zY0Y5eXBNSTFId3kwUjQzU3dUSUl3ajkr?=
 =?utf-8?B?ZERrcTlxYTR4NUtkamJZU0lFU0tpQXROeTZyb0g3YmRGMHRuMHloWWtYQUNC?=
 =?utf-8?B?WStpZEpZUWpNOVJ0T1lralZGWmtvOGErd01xTkoxNUhDbXc4eGFxQkFjUWdO?=
 =?utf-8?B?Zis0Y3plVCtYNndTRUdFd0VXQkRxRWt2eCs3K0JXYk9sdU5jdi9ZaSt3NUEw?=
 =?utf-8?B?WTRqS3VhenpVRWRVTm9mOU44QWFyMjZDNHR0WC9sbU1tRU5sR2ZiQ0tTV0tT?=
 =?utf-8?B?OUYrV09OZE9DY1hjZWRYN3VMZkVUR3NuVXEzeDlrZ2tRTHg4alJ0cmtsK1VX?=
 =?utf-8?B?dGRuSUJ1dExPbkM0YkNiVXNvV2tlV25qc01neG10ZlZ0cnpmRFBvSmQxNXUr?=
 =?utf-8?B?eDJveVJTZEZ1YWkvby9PQndoL0ZuQldiU0dyWEJBNGcwYjgySEN3Wk5HdWxl?=
 =?utf-8?B?ekppQ1JXb2NaSERJMDJsbWcxbWtvTEZaeTg4YkdmbHRTbmcvWVZFK0cxWWpi?=
 =?utf-8?B?KysxeStDQ1Z6V2VGL3pCV3RKWEo0MnhkMXBCakhMd0ZyQiszbzM3QUl2MTVw?=
 =?utf-8?B?QUNvQWpmRXEvZWp6UHk0N09STFZibU0wa29ubmNaTHJ0K1Z1RG8zdzdVR1Ez?=
 =?utf-8?B?U3JsSkJiajBtUlk3aUVaT1I1TklQbDVhd1NNbnB1RFlPdEU1cVJlSWpvS0JW?=
 =?utf-8?B?OHFBeHdGbVhvL09MSktKMmtwbHVNU0ZVSlh5amhUQ1NIdzFrVWFyeTdqS0pk?=
 =?utf-8?B?NHNzY2cwQUEzN2tIVDEvR0loaURQV0ZEeGNRNjRlcmVaWXVHYnpHazQ1MVBQ?=
 =?utf-8?B?QXFPOU5NL0RkWFFqNUlWNE1GUncycDVjcjhwMFRQQUM2NGR6S2luQ1VlSzcy?=
 =?utf-8?B?eW9hQURzVUhYVmIwcHM2VVNHM0cxQzNnWnVYbXZQNW82bm11cXVYRlpzYXo3?=
 =?utf-8?Q?TVVK0zxzGP/ol0BudmIpFc4urkN5Kdka5CEGccn?=
X-OriginatorOrg: Nvidia.com
X-MS-Exchange-CrossTenant-Network-Message-Id: 4a2db97e-f624-4c48-62e7-08d910a6a382
X-MS-Exchange-CrossTenant-AuthSource: MN2PR12MB3823.namprd12.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 06 May 2021 15:50:14.6251
 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a
X-MS-Exchange-CrossTenant-MailboxType: HOSTED
X-MS-Exchange-CrossTenant-UserPrincipalName: CSlfpw9kMOus/VnZHVM7zSMn6gYy3gYbyvASz5mWyiCkWbWBDH1hPjGsZAygXRag
X-MS-Exchange-Transport-CrossTenantHeadersStamped: BL0PR12MB2468
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

--=_MailMate_EF181C5B-F560-456C-BCA4-7AD984E499FD_=
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

On 6 May 2021, at 11:40, David Hildenbrand wrote:

>>>> The last patch increases SECTION_SIZE_BITS to demonstrate the use of=
 memory
>>>> hotplug/hotremove subsection, but is not intended to be merged as is=
=2E It is
>>>> there in case one wants to try this out and will be removed during t=
he final
>>>> submission.
>>>>
>>>> Feel free to give suggestions and comments. I am looking forward to =
your
>>>> feedback.
>>>
>>> Please not like this.
>>
>> Do you mind sharing more useful feedback instead of just saying a lot =
of No?
>
> I remember reasoning about this already in another thread, no? Either y=
ou're ignoring my previous feedback or my mind is messing with me.

I definitely remember all your suggestions:

1. do not use CMA allocation for 1GB THP.
2. section size defines the minimum size in which we can add_memory(), so=
 we cannot increase it.

I am trying an alternative here. I am not using CMA allocation and not in=
creasing the minimum size of add_memory() by decoupling the memory block =
size from section size, so that add_memory() can add a memory block small=
er (as small as 2MB, the subsection size) than section size. In this way,=
 section size can be increased freely. I do not see the strong tie betwee=
n add_memory() and section size, especially we have subsection bitmap sup=
port.


=E2=80=94
Best Regards,
Yan Zi

--=_MailMate_EF181C5B-F560-456C-BCA4-7AD984E499FD_=
Content-Description: OpenPGP digital signature
Content-Disposition: attachment; filename=signature.asc
Content-Type: application/pgp-signature; name=signature.asc

-----BEGIN PGP SIGNATURE-----
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=8W9n
-----END PGP SIGNATURE-----

--=_MailMate_EF181C5B-F560-456C-BCA4-7AD984E499FD_=--