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]) by smtp.lore.kernel.org (Postfix) with ESMTP id 693C5C433EF for ; Wed, 19 Jan 2022 13:44:27 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id C64496B0074; Wed, 19 Jan 2022 08:44:26 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id C141A6B0075; Wed, 19 Jan 2022 08:44:26 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B2A066B0078; Wed, 19 Jan 2022 08:44:26 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0025.hostedemail.com [216.40.44.25]) by kanga.kvack.org (Postfix) with ESMTP id A11826B0074 for ; Wed, 19 Jan 2022 08:44:26 -0500 (EST) Received: from smtpin24.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 67F071812E1E6 for ; Wed, 19 Jan 2022 13:44:26 +0000 (UTC) X-FDA: 79047156132.24.30581CD Received: from szxga03-in.huawei.com (szxga03-in.huawei.com [45.249.212.189]) by imf20.hostedemail.com (Postfix) with ESMTP id 3A0321C0023 for ; Wed, 19 Jan 2022 13:44:25 +0000 (UTC) Received: from dggpemm500023.china.huawei.com (unknown [172.30.72.55]) by szxga03-in.huawei.com (SkyGuard) with ESMTP id 4Jf6Hb6hngz8wNx; Wed, 19 Jan 2022 21:41:31 +0800 (CST) Received: from dggpemm500001.china.huawei.com (7.185.36.107) by dggpemm500023.china.huawei.com (7.185.36.83) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.21; Wed, 19 Jan 2022 21:44:21 +0800 Received: from [10.174.177.243] (10.174.177.243) by dggpemm500001.china.huawei.com (7.185.36.107) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256) id 15.1.2308.21; Wed, 19 Jan 2022 21:44:21 +0800 Message-ID: <93db576e-9a62-ee98-5af2-a62f8386212c@huawei.com> Date: Wed, 19 Jan 2022 21:44:20 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.2.0 Subject: Re: [PATCH v2 1/3] mm: vmalloc: Let user to control huge vmalloc default behavior Content-Language: en-US To: Matthew Wilcox CC: Nicholas Piggin , Andrew Morton , Jonathan Corbet , , , , , , , Benjamin Herrenschmidt , Borislav Petkov , Catalin Marinas , Christophe Leroy , Dave Hansen , "H. Peter Anvin" , Ingo Molnar , Michael Ellerman , "Paul Mackerras" , Thomas Gleixner , "Will Deacon" References: <20211227145903.187152-1-wangkefeng.wang@huawei.com> <20211227145903.187152-2-wangkefeng.wang@huawei.com> <1642473992.qrnqczjfna.astroid@bobo.none> From: Kefeng Wang In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed X-Originating-IP: [10.174.177.243] X-ClientProxiedBy: dggeme702-chm.china.huawei.com (10.1.199.98) To dggpemm500001.china.huawei.com (7.185.36.107) X-CFilter-Loop: Reflected X-Rspamd-Queue-Id: 3A0321C0023 X-Stat-Signature: pxuhe478tqacig8m5m8cio9kkctf4a4o Authentication-Results: imf20.hostedemail.com; dkim=none; spf=pass (imf20.hostedemail.com: domain of wangkefeng.wang@huawei.com designates 45.249.212.189 as permitted sender) smtp.mailfrom=wangkefeng.wang@huawei.com; dmarc=pass (policy=quarantine) header.from=huawei.com X-Rspamd-Server: rspam07 X-HE-Tag: 1642599865-377171 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 2022/1/19 21:22, Matthew Wilcox wrote: > On Wed, Jan 19, 2022 at 08:57:58PM +0800, Kefeng Wang wrote: >> Only parts of our products wants this feature,=C2=A0 we add some inter= faces which >> only >> >> alloc hugevmalloc for them, eg, >> vmap_hugepage/vmalloc_hugepage/remap_vmalloc_hugepage_range.. >> >> for our products, but it's not the choice of most products, also add >> nohugevmalloc >> >> for most products is expensive, so this is the reason for adding the p= atch. >> >> more config/cmdline are more flexible for test/products=EF=BC=8C > But why do only some products want it? What goes wrong if all products > enable it? Features should be auto-tuning, not relying on admins to > understand them. Because this feature will use more memory for vmalloc/vmap, that's why=20 we add some explicit interfaces as said above in our kernel to control the user.