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=-6.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 1AA49C43461 for ; Thu, 17 Sep 2020 00:49:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C63C6206CA for ; Thu, 17 Sep 2020 00:49:12 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=samsung.com header.i=@samsung.com header.b="LCUBOcKJ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726298AbgIQAtI (ORCPT ); Wed, 16 Sep 2020 20:49:08 -0400 Received: from mailout2.samsung.com ([203.254.224.25]:49148 "EHLO mailout2.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725886AbgIQAtA (ORCPT ); Wed, 16 Sep 2020 20:49:00 -0400 X-Greylist: delayed 351 seconds by postgrey-1.27 at vger.kernel.org; Wed, 16 Sep 2020 20:48:58 EDT Received: from epcas1p2.samsung.com (unknown [182.195.41.46]) by mailout2.samsung.com (KnoxPortal) with ESMTP id 20200917004302epoutp02fe54bc972b2e6ae76a4a5717878182c0~1a3J7B8XJ1951519515epoutp02J for ; Thu, 17 Sep 2020 00:43:02 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 mailout2.samsung.com 20200917004302epoutp02fe54bc972b2e6ae76a4a5717878182c0~1a3J7B8XJ1951519515epoutp02J DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=samsung.com; s=mail20170921; t=1600303382; bh=iF01R0RXpU+eG69rlPV5Od9C+ssN22uuhWON4+DSNWY=; h=Subject:Reply-To:From:To:CC:In-Reply-To:Date:References:From; b=LCUBOcKJm6KSsXIPiJQz8JOvW6JMijIvJ/3n/QU22bN7kaOdPeD5AND75hpnbbJpI XVKFZ9wNWV3W81XmsrAZxf7/htYSeDWLs7VqVq/NQJ//9Oh61jwuCz+omCaLGPJ/X7 DfZ3hRBh5Q6ZTOT7QvxxgL7h9LvA93W3s5GOAgZc= Received: from epcpadp2 (unknown [182.195.40.12]) by epcas1p2.samsung.com (KnoxPortal) with ESMTP id 20200917004301epcas1p25b5958440691a33befafc83db482b36e~1a3JhP3uT1274212742epcas1p27; Thu, 17 Sep 2020 00:43:01 +0000 (GMT) Mime-Version: 1.0 Subject: Re: [PATCH v11 0/4] scsi: ufs: Add Host Performance Booster Support Reply-To: daejun7.park@samsung.com From: Daejun Park To: Christoph Hellwig , Daejun Park CC: "avri.altman@wdc.com" , "jejb@linux.ibm.com" , "martin.petersen@oracle.com" , "asutoshd@codeaurora.org" , "beanhuo@micron.com" , "stanley.chu@mediatek.com" , "cang@codeaurora.org" , "bvanassche@acm.org" , "tomas.winkler@intel.com" , ALIM AKHTAR , "linux-scsi@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Sang-yoon Oh , Sung-Jun Park , yongmyung lee , Jinyoung CHOI , Adel Choi , BoRam Shin , SEUNGUK SHIN X-Priority: 3 X-Content-Kind-Code: NORMAL In-Reply-To: <20200916052208.GB12923@infradead.org> X-CPGS-Detection: blocking_info_exchange X-Drm-Type: N,general X-Msg-Generator: Mail X-Msg-Type: PERSONAL X-Reply-Demand: N Message-ID: <231786897.01600303381578.JavaMail.epsvc@epcpadp2> Date: Thu, 17 Sep 2020 09:25:50 +0900 X-CMS-MailID: 20200917002550epcms2p168eb4c7e2fb77f7f31a5db2f3522e256 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="utf-8" X-Sendblock-Type: AUTO_CONFIDENTIAL X-CPGSPASS: Y X-CPGSPASS: Y X-Hop-Count: 3 X-CMS-RootMailID: 20200902031713epcms2p664cebf386ba19d3d05895fec89aaf4fe References: <20200916052208.GB12923@infradead.org> <231786897.01599016802080.JavaMail.epsvc@epcpadp1> <231786897.01600211401846.JavaMail.epsvc@epcpadp1> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > > Hi All, > > > > I want to know how to improve this patch. > > Drop it and fix the actual UFS feature to not be so horrible? > Hello Christoph, Thanks for the comment. The HPB is essential feature for mobile devices. NAND-based storage needs logical to physical mapping, which is cached in the storage to minimize translation overhead. UFS is a NAND-based storage device with limited resources, mainly used for mobile devices. Typically, SSD has enough cache space for mapping information in SSD, but UFS has not enough. So, UFS stores L2P mapping in NAND and performs IO using demand loading for translation. Due to overhead of demand loading, it degrades random read performance. The HPB is a feature which uses host memory to relieve this problem. By using the HPB feature, UFS can provide improved random read performance without mapping data thrashing problem. Therefore, the HPB is currently already included in the Linux kernel code in android devices, however it is maintained as out-of-tree. While upstreaming HPB feature to mainline kernel, we received various comments from several reviewers (thanks!) and the HPB feature can be improved. I think it would be good to make mainline the feature that are mainly used. Thanks, Daejun