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=-0.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY 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 7DCFDC432C3 for ; Thu, 28 Nov 2019 12:17:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 54209217D6 for ; Thu, 28 Nov 2019 12:17:03 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="U899dvbj" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726694AbfK1MRC (ORCPT ); Thu, 28 Nov 2019 07:17:02 -0500 Received: from aserp2120.oracle.com ([141.146.126.78]:57640 "EHLO aserp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726227AbfK1MRC (ORCPT ); Thu, 28 Nov 2019 07:17:02 -0500 Received: from pps.filterd (aserp2120.oracle.com [127.0.0.1]) by aserp2120.oracle.com (8.16.0.27/8.16.0.27) with SMTP id xASCEURn041078; Thu, 28 Nov 2019 12:15:20 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=to : cc : subject : from : references : date : in-reply-to : message-id : mime-version : content-type; s=corp-2019-08-05; bh=K23tF4ZOTDK2mqDQjS6SPO2vyRMwZ30j/1NOK4W0JhU=; b=U899dvbj2nf503rUrhC7bjlnabTEc8CnGq3kxTbIN9FQZZ7PaHselctxJP0PdlYJaLh1 MtUr7y3iYlfnHUUoy7vW84HeRpysuJAHISh6hp36cHyPZ8CrfKPoUBbZerKOHfreJwJl 7UyhVeXac0Z2hHde+5XqVvg+llnJGS44sBpSHGrgmhKkhT/zKgScPs5ijVSg3N9rSZEt 0MpHQyi4PugxpNgdpMGeUxSXJyw4X+sETczYGhlCdIvjimklQs6DGtd17fc/S8IXirJi TkpL89TnxKaDyZDfgmvkf9es+AiGbWfo8LmUTCQ6BreW71hxMJ8MdO+fmzWmLT2jn2tT Pg== Received: from userp3030.oracle.com (userp3030.oracle.com [156.151.31.80]) by aserp2120.oracle.com with ESMTP id 2wevqqkbnc-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 28 Nov 2019 12:15:20 +0000 Received: from pps.filterd (userp3030.oracle.com [127.0.0.1]) by userp3030.oracle.com (8.16.0.27/8.16.0.27) with SMTP id xASCEOYE100925; Thu, 28 Nov 2019 12:15:19 GMT Received: from userv0121.oracle.com (userv0121.oracle.com [156.151.31.72]) by userp3030.oracle.com with ESMTP id 2why49ykr4-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 28 Nov 2019 12:15:19 +0000 Received: from abhmp0015.oracle.com (abhmp0015.oracle.com [141.146.116.21]) by userv0121.oracle.com (8.14.4/8.13.8) with ESMTP id xASCFD2B023073; Thu, 28 Nov 2019 12:15:14 GMT Received: from ca-mkp.ca.oracle.com (/10.159.214.123) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Thu, 28 Nov 2019 04:15:12 -0800 To: Christoph Hellwig Cc: Hannes Reinecke , Arnd Bergmann , "\(Exiting\) Baolin Wang" , Baolin Wang , Adrian Hunter , Ulf Hansson , asutoshd@codeaurora.org, Orson Zhai , Lyra Zhang , Linus Walleij , Vincent Guittot , linux-mmc , "linux-kernel\@vger.kernel.org" , Hannes Reinecke , linux-block , Paolo Valente Subject: Re: [PATCH v6 0/4] Add MMC software queue support From: "Martin K. Petersen" Organization: Oracle Corporation References: <20191127090023.GA23040@infradead.org> Date: Thu, 28 Nov 2019 07:15:09 -0500 In-Reply-To: <20191127090023.GA23040@infradead.org> (Christoph Hellwig's message of "Wed, 27 Nov 2019 01:00:23 -0800") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1.92 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9454 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=949 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1911140001 definitions=main-1911280108 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9454 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1011 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1911140001 definitions=main-1911280108 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Christoph, > equivalent to SCSI logical units and nvme namespace, just with a > pretty idiotic design decision that only allows I/O to one of them at > a time. The block layer way to deal with them is to use a shared > tagset for multiple request queues, which doesn't use up a whole lot > of resources. The only hard part is the draining when switching > between partitions, and there is no really nice way to deal with that. > If requests are batched enough we could just drain and switch every > time an other partition access comes in. This mirrors single_lun in SCSI closely. I was hoping we could eventually get rid of that travesty but if MMC needs something similar, maybe it would be good to move that plumbing to block? -- Martin K. Petersen Oracle Linux Engineering