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=-3.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=no 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 953FBC433E7 for ; Mon, 12 Oct 2020 12:13:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 583A8208FE for ; Mon, 12 Oct 2020 12:13:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388400AbgJLMNd convert rfc822-to-8bit (ORCPT ); Mon, 12 Oct 2020 08:13:33 -0400 Received: from szxga01-in.huawei.com ([45.249.212.187]:3631 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S2388209AbgJLMNd (ORCPT ); Mon, 12 Oct 2020 08:13:33 -0400 X-Greylist: delayed 966 seconds by postgrey-1.27 at vger.kernel.org; Mon, 12 Oct 2020 08:13:32 EDT Received: from DGGEMM405-HUB.china.huawei.com (unknown [172.30.72.56]) by Forcepoint Email with ESMTP id 000DCF8DF6F97C310D13; Mon, 12 Oct 2020 19:57:24 +0800 (CST) Received: from DGGEMM526-MBX.china.huawei.com ([169.254.8.75]) by DGGEMM405-HUB.china.huawei.com ([10.3.20.213]) with mapi id 14.03.0487.000; Mon, 12 Oct 2020 19:57:21 +0800 From: "Zengtao (B)" To: "yulei.kernel@gmail.com" , "akpm@linux-foundation.org" , "naoya.horiguchi@nec.com" , "viro@zeniv.linux.org.uk" , "pbonzini@redhat.com" CC: "linux-fsdevel@vger.kernel.org" , "kvm@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "xiaoguangrong.eric@gmail.com" , "kernellwp@gmail.com" , "lihaiwei.kernel@gmail.com" , Yulei Zhang Subject: RE: [PATCH 00/35] Enhance memory utilization with DMEMFS Thread-Topic: [PATCH 00/35] Enhance memory utilization with DMEMFS Thread-Index: AQHWnUhD+KX8RHawSUyoBEEGXF5fO6mT4mTw Date: Mon, 12 Oct 2020 11:57:20 +0000 Message-ID: <678F3D1BB717D949B966B68EAEB446ED49E01801@dggemm526-mbx.china.huawei.com> References: In-Reply-To: Accept-Language: zh-CN, en-US Content-Language: zh-CN X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.74.221.187] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org > -----Original Message----- > From: yulei.kernel@gmail.com [mailto:yulei.kernel@gmail.com] > Sent: Thursday, October 08, 2020 3:54 PM > To: akpm@linux-foundation.org; naoya.horiguchi@nec.com; > viro@zeniv.linux.org.uk; pbonzini@redhat.com > Cc: linux-fsdevel@vger.kernel.org; kvm@vger.kernel.org; > linux-kernel@vger.kernel.org; xiaoguangrong.eric@gmail.com; > kernellwp@gmail.com; lihaiwei.kernel@gmail.com; Yulei Zhang > Subject: [PATCH 00/35] Enhance memory utilization with DMEMFS > > From: Yulei Zhang > > In current system each physical memory page is assocaited with > a page structure which is used to track the usage of this page. > But due to the memory usage rapidly growing in cloud environment, > we find the resource consuming for page structure storage becomes > highly remarkable. So is it an expense that we could spare? > > This patchset introduces an idea about how to save the extra > memory through a new virtual filesystem -- dmemfs. > > Dmemfs (Direct Memory filesystem) is device memory or reserved > memory based filesystem. This kind of memory is special as it > is not managed by kernel and most important it is without 'struct page'. > Therefore we can leverage the extra memory from the host system > to support more tenants in our cloud service. > > We uses a kernel boot parameter 'dmem=' to reserve the system > memory when the host system boots up, the details can be checked > in /Documentation/admin-guide/kernel-parameters.txt. > > Theoretically for each 4k physical page it can save 64 bytes if > we drop the 'struct page', so for guest memory with 320G it can > save about 5G physical memory totally. Sounds interesting, but seems your patch only support x86, have you considered aarch64? Regards Zengtao