From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755662AbcKBOzj (ORCPT ); Wed, 2 Nov 2016 10:55:39 -0400 Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:33676 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753519AbcKBOzg (ORCPT ); Wed, 2 Nov 2016 10:55:36 -0400 Subject: Re: [PATCH 1/4] block: add scalable completion tracking of requests To: Christoph Hellwig References: <1478034325-28232-1-git-send-email-axboe@fb.com> <1478034325-28232-2-git-send-email-axboe@fb.com> <20161102145239.GB13964@lst.de> CC: , , From: Jens Axboe Message-ID: <1954bf49-eeff-0b16-3cf9-7d7d02f25562@fb.com> Date: Wed, 2 Nov 2016 08:55:16 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 MIME-Version: 1.0 In-Reply-To: <20161102145239.GB13964@lst.de> Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [64.134.26.173] X-ClientProxiedBy: YQXPR01CA0017.CANPRD01.PROD.OUTLOOK.COM (10.165.102.155) To BN6PR15MB1188.namprd15.prod.outlook.com (10.172.205.142) X-MS-Office365-Filtering-Correlation-Id: b83d5e78-de4a-440a-53b4-08d4033046c1 X-Microsoft-Exchange-Diagnostics: 1;BN6PR15MB1188;2:tZ1GsUSunGDHvwN9iVCIMq4XdDiHSlS8oMhpAxg6APsZuvImMTludK0hZPpEJQEEDChfbs1eKARIjcXaDUPoWcoRvXJLiSL/XYDiQ3QYIf2a/90BcWW10lpZp/KT2HV4CbWmj4tq5S9j6quvRwgUeQcRoyyjSHe7xVPt339mRY+iBXUdcEEjn6kNeeS2rO+JzBmBDW1kktCs2ESs+E7szg==;3:uunlGPVpGRGBG9sUGqRO9FjlxHCwRnSM+/FMtFyvyMUc2SddX0PO36y3RWtub2rPQeJapBeIj/Ml1YdR7fwqoy8gNZ6FafVtKIXDn6fE7tfkAKW6reclAbygfT9gk+nL7o7nPNiotoZIVU/mduwWwg==;25:1imrJ6BLH5OsZHP35i7WM7B2z8Kw9ONXn/4ZD4zyx6jDDTsWa6RQsxMvx47xbevg99VeS6Nnjl+NUxzKDe67q1Wh0mdA/HBSFPuPj0gdt6i70Lu5d4Q91D8NG36IPIkiEUUZBkG6nywL0Q7aLQS99Nz8mmP8JJFHr9D1FnhwnESQMvVbP5/zMGgjnOfiIwNG8r/BBvVwxR1Mo82dMZQlohNrr8pZKNhusxveCa/i530FE07zDiLOihZEvDllbeUdjrtdId/gg6iPg6r1ksaNQx8x9AFMUtcs8tl7UtmT1XctGwms9MnIR3035fNDSzFRUCowvOiI6ku2ZdR2td/iyUmRLQnmqCNXqnBZe8bmS31WYYoj2DkJOKnI3cE/zCMZw7XnhKlp7kRpG5bCoxIuAgcRpdGq05yUY+nC9yEytpCh9He1qR9iDVeY2IggLSZO X-Microsoft-Antispam: UriScan:;BCL:0;PCL:0;RULEID:;SRVR:BN6PR15MB1188; 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For >> blk-mq, we track them on a per-sw queue basis, which we can then >> sum up through the hardware queues and finally to a per device >> state. > > what is the use case for the legacy request tracking? Buffered writeback code uses the same base. Additionally, it could replace some user space tracking for latency outliers that people are currently running. -- Jens Axboe