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 8086CC43215 for ; Fri, 22 Nov 2019 02:19:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 51F11206EC for ; Fri, 22 Nov 2019 02:19:14 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="b9KnwfKt" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726408AbfKVCTN (ORCPT ); Thu, 21 Nov 2019 21:19:13 -0500 Received: from userp2120.oracle.com ([156.151.31.85]:52160 "EHLO userp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726329AbfKVCTN (ORCPT ); Thu, 21 Nov 2019 21:19:13 -0500 Received: from pps.filterd (userp2120.oracle.com [127.0.0.1]) by userp2120.oracle.com (8.16.0.27/8.16.0.27) with SMTP id xAM2IxBA126127; Fri, 22 Nov 2019 02:18:59 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=2zVKy8FtHTdWztCQJccE9woCczDrdMZAePdPXZ54Hio=; b=b9KnwfKtGecVuXTex8O0Ff6OhTRdsFPxqw2oB/HhTBUmuo0WlQCPIralZG8uP9BQa8px rGkjMzZbUXGZQzdxBDQtLCBlzJzTeYHKWbJdrmoNErp8Eo0nQgI/ZBzylNH/meDTOJNl DeTFU96V+10B/NOpASJXsNZ4QZcQVYtcf//h/mhtOHBIDXkDcv2EgKeYLrH/K+9+wDX5 Tlq+pzZyxM7IjbH+1ka8m75qd5IWSwkjPgrn2o1nZut6E3HiF2LdRCXvJ+ak+nJ1RUbk CE+rGGgaHgserBk7KNetjPVWOjYvkfb/ALolka2g/F3hlS46Y9OlNrjrmUQ1quBDY0TH 7A== Received: from aserp3030.oracle.com (aserp3030.oracle.com [141.146.126.71]) by userp2120.oracle.com with ESMTP id 2wa9rqyudu-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 22 Nov 2019 02:18:59 +0000 Received: from pps.filterd (aserp3030.oracle.com [127.0.0.1]) by aserp3030.oracle.com (8.16.0.27/8.16.0.27) with SMTP id xAM2HwsR137371; Fri, 22 Nov 2019 02:18:58 GMT Received: from aserv0122.oracle.com (aserv0122.oracle.com [141.146.126.236]) by aserp3030.oracle.com with ESMTP id 2wd47y1g06-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 22 Nov 2019 02:18:58 +0000 Received: from abhmp0003.oracle.com (abhmp0003.oracle.com [141.146.116.9]) by aserv0122.oracle.com (8.14.4/8.14.4) with ESMTP id xAM2IuvK015687; Fri, 22 Nov 2019 02:18:56 GMT Received: from ca-mkp.ca.oracle.com (/10.159.214.123) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Thu, 21 Nov 2019 18:18:55 -0800 To: Hannes Reinecke Cc: Ming Lei , Jens Axboe , linux-block@vger.kernel.org, "James E . J . Bottomley" , "Martin K . Petersen" , linux-scsi@vger.kernel.org, Sathya Prakash , Chaitra P B , Suganath Prabu Subramani , Kashyap Desai , Sumit Saxena , Shivasharan S , "Ewan D . Milne" , Christoph Hellwig , Bart Van Assche Subject: Re: [PATCH 4/4] scsi: core: don't limit per-LUN queue depth for SSD From: "Martin K. Petersen" Organization: Oracle Corporation References: <20191118103117.978-1-ming.lei@redhat.com> <20191118103117.978-5-ming.lei@redhat.com> <1081145f-3e17-9bc1-2332-50a4b5621ef7@suse.de> Date: Thu, 21 Nov 2019 21:18:51 -0500 In-Reply-To: <1081145f-3e17-9bc1-2332-50a4b5621ef7@suse.de> (Hannes Reinecke's message of "Wed, 20 Nov 2019 11:05:24 +0100") 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=9448 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=645 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1911140001 definitions=main-1911220019 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9448 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=710 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1911140001 definitions=main-1911220019 Sender: linux-scsi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org Hannes, > I must admit I patently don't like this explicit dependency on > blk_nonrot(). The whole idea behind using rotational/non-rotational as a trigger for this is a red herring. Fast devices also have internal queuing limitations. And more importantly: Fast devices also experience temporary shortages which can lead to congestion. -- Martin K. Petersen Oracle Linux Engineering