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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 0CFDBE9904C for ; Fri, 10 Apr 2026 07:45:08 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 1A9D46B0005; Fri, 10 Apr 2026 03:45:08 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 15B226B0089; Fri, 10 Apr 2026 03:45:08 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0499B6B008A; Fri, 10 Apr 2026 03:45:07 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id E7E9E6B0005 for ; Fri, 10 Apr 2026 03:45:07 -0400 (EDT) Received: from smtpin14.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 8FB6C1B77E9 for ; Fri, 10 Apr 2026 07:45:07 +0000 (UTC) X-FDA: 84641860254.14.5759590 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf04.hostedemail.com (Postfix) with ESMTP id C35DE40004 for ; Fri, 10 Apr 2026 07:45:05 +0000 (UTC) Authentication-Results: imf04.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=OLT0prWj; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf04.hostedemail.com: domain of david@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=david@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1775807105; h=from:from:sender: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:dkim-signature; bh=Ly7znywkofd3JB7DcRaDynC5T65ZOT2rFIFech2jAG8=; b=K0Mmwv2kY65SDTgqGcF4qmAvOtY3EORbJbyud0xV812kMmKwxzj+AQtnuLcEErAw43f+ni pphqaW/GScxnUjJXYgBk2k5YOI3EPMvkQdApSY/Ac3yEEzcF/SuLtVZsfpcNGEZic1El0A fLLduq3si7oGIJpKE+kWk+epqcA+YcQ= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1775807105; a=rsa-sha256; cv=none; b=ZvKMBJDqZYUGabl8lcKq5YbRzDF1VuW13SQObZ849EcASnGJOwaPDLJ6pzOu9tudkElaTF NN/gSNagEp+s7TsE9L73sXCbRrGDLVSHzKJ6ENgM6pgCLpBFzck6A18aXpZ5jtZ1QvJ+P1 QOKQxi6PIfLrD4u5+5G05knROZAADu4= ARC-Authentication-Results: i=1; imf04.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=OLT0prWj; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf04.hostedemail.com: domain of david@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=david@kernel.org Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id B300260126; Fri, 10 Apr 2026 07:45:04 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8123EC19421; Fri, 10 Apr 2026 07:45:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1775807104; bh=DtPmOk5kJ/H1o3+QUlVWzL6Vnpd4A2X9fTpGymihk4s=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=OLT0prWjcLBJjNG9IaNrY4LsYY74iPhY8gJqZc+q3w3DPqJjCATdr2qsL1x9jS2jT nyGL/NlVRSoOczjSkNjoYNHk7RhOd0FKY3hmmQCN3dpW58ritiaivgq8vTPWIh6rwO MgRL5nfIKqbEGXUeoXiNxZF3REqOq7PWTbQSo/TACVh267ge3wPAigxY4uZugbXNV+ +IYxfTiqgngGTk6yVeG3n7zr8ndnw5KeyFjdxzjjAXxGLyQ4XK/Ssmn4patMExm63j sccGpHBFSxccYGV6fhOVfynLRZeGL3FKNzxeRcQygx4GYPlm8y30qv7hao3tshcVBW +nXBaqtdJ0irw== Message-ID: Date: Fri, 10 Apr 2026 09:44:59 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH] mm/sparse: remove sparse_buffer To: Muchun Song , Mike Rapoport Cc: Muchun Song , Andrew Morton , yinghai@kernel.org, Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Suren Baghdasaryan , Michal Hocko , linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20260407083951.2823915-1-songmuchun@bytedance.com> <70EF8E41-31A2-4B43-BABE-7218FD5F7271@linux.dev> <45BF3CAC-2E64-4CA7-A7B8-800FC90930D5@linux.dev> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; keydata= xsFNBFXLn5EBEAC+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 B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzS5EYXZpZCBIaWxk ZW5icmFuZCAoQ3VycmVudCkgPGRhdmlkQGtlcm5lbC5vcmc+wsGQBBMBCAA6AhsDBQkmWAik AgsJBBUKCQgCFgICHgUCF4AWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaYJt/AIZAQAKCRBN 3hD3AP+DWriiD/9BLGEKG+N8L2AXhikJg6YmXom9ytRwPqDgpHpVg2xdhopoWdMRXjzOrIKD g4LSnFaKneQD0hZhoArEeamG5tyo32xoRsPwkbpIzL0OKSZ8G6mVbFGpjmyDLQCAxteXCLXz ZI0VbsuJKelYnKcXWOIndOrNRvE5eoOfTt2XfBnAapxMYY2IsV+qaUXlO63GgfIOg8RBaj7x 3NxkI3rV0SHhI4GU9K6jCvGghxeS1QX6L/XI9mfAYaIwGy5B68kF26piAVYv/QZDEVIpo3t7 /fjSpxKT8plJH6rhhR0epy8dWRHk3qT5tk2P85twasdloWtkMZ7FsCJRKWscm1BLpsDn6EQ4 jeMHECiY9kGKKi8dQpv3FRyo2QApZ49NNDbwcR0ZndK0XFo15iH708H5Qja/8TuXCwnPWAcJ DQoNIDFyaxe26Rx3ZwUkRALa3iPcVjE0//TrQ4KnFf+lMBSrS33xDDBfevW9+Dk6IISmDH1R HFq2jpkN+FX/PE8eVhV68B2DsAPZ5rUwyCKUXPTJ/irrCCmAAb5Jpv11S7hUSpqtM/6oVESC 3z/7CzrVtRODzLtNgV4r5EI+wAv/3PgJLlMwgJM90Fb3CB2IgbxhjvmB1WNdvXACVydx55V7 LPPKodSTF29rlnQAf9HLgCphuuSrrPn5VQDaYZl4N/7zc2wcWM7BTQRVy5+RARAA59fefSDR 9nMGCb9LbMX+TFAoIQo/wgP5XPyzLYakO+94GrgfZjfhdaxPXMsl2+o8jhp/hlIzG56taNdt VZtPp3ih1AgbR8rHgXw1xwOpuAd5lE1qNd54ndHuADO9a9A0vPimIes78Hi1/yy+ZEEvRkHk /kDa6F3AtTc1m4rbbOk2fiKzzsE9YXweFjQvl9p+AMw6qd/iC4lUk9g0+FQXNdRs+o4o6Qvy iOQJfGQ4UcBuOy1IrkJrd8qq5jet1fcM2j4QvsW8CLDWZS1L7kZ5gT5EycMKxUWb8LuRjxzZ 3QY1aQH2kkzn6acigU3HLtgFyV1gBNV44ehjgvJpRY2cC8VhanTx0dZ9mj1YKIky5N+C0f21 zvntBqcxV0+3p8MrxRRcgEtDZNav+xAoT3G0W4SahAaUTWXpsZoOecwtxi74CyneQNPTDjNg azHmvpdBVEfj7k3p4dmJp5i0U66Onmf6mMFpArvBRSMOKU9DlAzMi4IvhiNWjKVaIE2Se9BY FdKVAJaZq85P2y20ZBd08ILnKcj7XKZkLU5FkoA0udEBvQ0f9QLNyyy3DZMCQWcwRuj1m73D sq8DEFBdZ5eEkj1dCyx+t/ga6x2rHyc8Sl86oK1tvAkwBNsfKou3v+jP/l14a7DGBvrmlYjO 59o3t6inu6H7pt7OL6u6BQj7DoMAEQEAAcLBfAQYAQgAJgIbDBYhBBvZyq1zXEw6Rg38yk3e EPcA/4NaBQJonNqrBQkmWAihAAoJEE3eEPcA/4NaKtMQALAJ8PzprBEXbXcEXwDKQu+P/vts IfUb1UNMfMV76BicGa5NCZnJNQASDP/+bFg6O3gx5NbhHHPeaWz/VxlOmYHokHodOvtL0WCC 8A5PEP8tOk6029Z+J+xUcMrJClNVFpzVvOpb1lCbhjwAV465Hy+NUSbbUiRxdzNQtLtgZzOV Zw7jxUCs4UUZLQTCuBpFgb15bBxYZ/BL9MbzxPxvfUQIPbnzQMcqtpUs21CMK2PdfCh5c4gS sDci6D5/ZIBw94UQWmGpM/O1ilGXde2ZzzGYl64glmccD8e87OnEgKnH3FbnJnT4iJchtSvx yJNi1+t0+qDti4m88+/9IuPqCKb6Stl+s2dnLtJNrjXBGJtsQG/sRpqsJz5x1/2nPJSRMsx9 5YfqbdrJSOFXDzZ8/r82HgQEtUvlSXNaXCa95ez0UkOG7+bDm2b3s0XahBQeLVCH0mw3RAQg r7xDAYKIrAwfHHmMTnBQDPJwVqxJjVNr7yBic4yfzVWGCGNE4DnOW0vcIeoyhy9vnIa3w1uZ 3iyY2Nsd7JxfKu1PRhCGwXzRw5TlfEsoRI7V9A8isUCoqE2Dzh3FvYHVeX4Us+bRL/oqareJ CIFqgYMyvHj7Q06kTKmauOe4Nf0l0qEkIuIzfoLJ3qr5UyXc2hLtWyT9Ir+lYlX9efqh7mOY qIws/H2t In-Reply-To: <45BF3CAC-2E64-4CA7-A7B8-800FC90930D5@linux.dev> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: C35DE40004 X-Stat-Signature: xx7sgsoqoobsc64c6iuc4qj1pz4izqtm X-Rspam-User: X-Rspamd-Server: rspam02 X-HE-Tag: 1775807105-308399 X-HE-Meta: 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 HKmryH0e 8iIoJAKXYK/POzgv956zMF2kOXfKVVPNatsENaZLOdX0Ea+YvpOWDqVyOJ95xLx6tbsdpjpjYNjJQUxqB/R7Usn+sgcFM55gkI2UO+AlA+xqk1NzbSvyb6A60VSyTGl6BcA6z45BvOF5dcI2i3hMVYf23nH0KxiSSzhRkg5wqX6gwTBr9jErJT6oyJftwU2P0yxtZjx2EdimGm2an3nI9FP/3BZmupp6LMz2rUSVNclhUUJWqRobKnzUW3FLvskT6sP/HHLNaMV8doG/uDmD/4uw4IPojamnQs0RpK5+OXXt+oYDjTpPnhdfXBjJAs2ufzhAIY92T0Kecl4U= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 4/10/26 08:05, Muchun Song wrote: > > >> On Apr 10, 2026, at 11:07, Muchun Song wrote: >> >> >> >>> >>> Hi, >>> >>> >>> memblock always allocates in order, so if there are no other memblock >>> allocations between the calls to memmap_alloc(), all these allocations will >>> be together and they all will be coalesced to a single region in >>> memblock.reserved. >>> >>> >>> ... >>> >>> >>> memmap_alloc() will be slower than sparse_buffer_alloc(), allocating from >>> memblock is more involved that sparse_buffer_alloc(), but without >>> measurements it's hard to tell how much it'll affect overall sparse_init(). >> >> I ran a test on a 256GB VM, and the results are as follows: >> >> With patch: 741,292 ns >> Without patch: 199,555 ns >> >> The performance is approximately 3.7x slower with the patch applied. > > I also tested 512GB of data, and the results were roughly twice that > of 256GB, so for a 1TB machine, the memory allocation time is only a > few milliseconds. It seems we don’t need to worry about the 3.7x > performance drop. Good. Can you incorporate all that into the patch description? -- Cheers, David