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 CE016C3F68F for ; Tue, 28 Jan 2020 04:23:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A4E512467E for ; Tue, 28 Jan 2020 04:23:37 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="XqNc0O72" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726267AbgA1EXf (ORCPT ); Mon, 27 Jan 2020 23:23:35 -0500 Received: from userp2130.oracle.com ([156.151.31.86]:46848 "EHLO userp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726080AbgA1EXf (ORCPT ); Mon, 27 Jan 2020 23:23:35 -0500 Received: from pps.filterd (userp2130.oracle.com [127.0.0.1]) by userp2130.oracle.com (8.16.0.27/8.16.0.27) with SMTP id 00S4NE1V037805; Tue, 28 Jan 2020 04:23:22 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=M37/lXKBiBEp6qH6zPjw/skt+VvxL1DBqovNM+NSYDo=; b=XqNc0O72SHdaNHogRvhTEgCWmwfej++xfd4GiWOv1zqeTZjXKE5bS9AWnVQUQrLwXmPR JuOEOQgwowClkgfpjxsON1fU+i8ZRo3HGj7UmmqeJU4LxLoAJ7xSnXqGL4dZ3XEVhNwD Ui0ySuDxk4v3TJujh4m5dCZmj5yrddhrTSnQNteI8Kakxr0U0v0w4A/tcfyA8daHCyv1 ognIzI7cf4rDLDbmOA7/FlWbtm49Da74a0CaJO69Uu7vs29Mi+lcJQD+62nEo2wScWrl 4KAXwkTXdfPgomQlX74hMq7s+Z2zfsabd0k0ugcCC1NxnA777+wqJLt8cQZmj3A0bxkI HQ== Received: from userp3020.oracle.com (userp3020.oracle.com [156.151.31.79]) by userp2130.oracle.com with ESMTP id 2xrd3u3h6x-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 28 Jan 2020 04:23:22 +0000 Received: from pps.filterd (userp3020.oracle.com [127.0.0.1]) by userp3020.oracle.com (8.16.0.27/8.16.0.27) with SMTP id 00S4NKv1182696; Tue, 28 Jan 2020 04:23:22 GMT Received: from userv0122.oracle.com (userv0122.oracle.com [156.151.31.75]) by userp3020.oracle.com with ESMTP id 2xta8gtfv0-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 28 Jan 2020 04:23:22 +0000 Received: from abhmp0012.oracle.com (abhmp0012.oracle.com [141.146.116.18]) by userv0122.oracle.com (8.14.4/8.14.4) with ESMTP id 00S4N3JO000985; Tue, 28 Jan 2020 04:23:04 GMT Received: from ca-mkp.ca.oracle.com (/10.159.214.123) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Mon, 27 Jan 2020 20:23:03 -0800 To: Sumanesh Samanta Cc: "Martin K. Petersen" , linux-scsi@vger.kernel.org, James Bottomley , Jens Axboe , Sathya Prakash , Chaitra P B , Suganath Prabu Subramani , Kashyap Desai , Shivasharan S , "Ewan D . Milne" , Christoph Hellwig , Hannes Reinecke , Bart Van Assche , Ming Lei , linux-block@vger.kernel.org, Sumit Saxena Subject: Re: [PATCH 5/6] scsi: core: don't limit per-LUN queue depth for SSD when HBA needs From: "Martin K. Petersen" Organization: Oracle Corporation References: <20200119071432.18558-1-ming.lei@redhat.com> <20200119071432.18558-6-ming.lei@redhat.com> Date: Mon, 27 Jan 2020 23:22:59 -0500 In-Reply-To: (Sumanesh Samanta's message of "Fri, 24 Jan 2020 12:41:20 -0700") 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=9513 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=983 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1911140001 definitions=main-2001280034 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9513 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=1015 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-2001280034 Sender: linux-scsi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org Sumanesh, > Instead of relying on QUEUE_FULL and some complex heuristics of when > to start tracking device_busy, why can't we simply use " > track_queue_depth" ( along with the other flag that Ming added) to > decide which devices need queue depth tracking, and track device_busy > only for them? Because I am interested in addressing the device_busy contention problem for all of our non-legacy drivers. I.e. not just for controllers that happen to queue internally. > I am not sure how we can suddenly start tracking device_busy on the fly, > if we do not know how many IO are already pending for that device? We know that from the tags. It's just not hot path material. -- Martin K. Petersen Oracle Linux Engineering