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,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED 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 0F0CBC43331 for ; Tue, 12 Nov 2019 21:20:42 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id D287620659 for ; Tue, 12 Nov 2019 21:20:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="oMyLzVQg"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=microsoft.com header.i=@microsoft.com header.b="LdpsCzal" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D287620659 Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=microsoft.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:In-Reply-To:References: Message-ID:Date:Subject:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=5YBk8Ng1cTN+6asbz4n8zbux1g3uSYcVUAzoQS7sJaw=; b=oMyLzVQgW3ohp4 FgdZuzWDpbPCx149qdB224rkNdbfINu8LFVLZzaxaYGo2lkXXHTDd4QtiOPiMEiRucWbKuD2QRas/ JySjcCq3p7hDPHVW+Dv0i3GtbLlaiN5GFWFthIjvMm5xwkcKVs1dRerTjq2Q6FMI3HPuaYtYRJun3 1I9y/l2i4z9NAGqWXFdq3pcx210usahHBmlbc+mXywU/NfPu75LlyFVY0/+QzYm2hOeomFpPAp3kh lsUdqHLZrWP+S65aPezXZsYNZ2u/mp655L0DGGHxvATfI5EprQPHW1/G2YuEdC6aQW66N30rUQQT2 Vbv6gv8xlDBqcUdKgT9g==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1iUdaZ-0000rC-Oi; Tue, 12 Nov 2019 21:20:39 +0000 Received: from mail-dm3nam05on0709.outbound.protection.outlook.com ([2a01:111:f400:fe51::709] helo=NAM05-DM3-obe.outbound.protection.outlook.com) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1iUdaR-0000qi-2T for linux-nvme@lists.infradead.org; Tue, 12 Nov 2019 21:20:37 +0000 ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=KjCugAjE5DA/49l2Y3NOzTuU3czUgLkSu62gyBkjkOrRmExwCbt4rRvyJymg6v0IwiUY70RN8DTbj4qx1EmR6/ANKUOw7DnfQNuoA/sQ7Xx7UYWPqGvRPEnDInK9B8eNamVj4aNU/ZQvRqXpFNwT1nJG0THo8vRQ38cXr53251bS7BAfRSowfypXicZYqMhY95Mx5c91gKGpvkPH57PD+yDzsQo1L0IYWbVqyCm99l9RYbAWJfLYGqJFeRMYCE41/RkdiGTVJqUXPY+7Lx62ggMlBRLYEbCiPPbvGWgh7epnsaDL1py907IUlP4cRkvSAUkxMrzHwUax8I0KRryXwg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=oBot/PQOI/u19tbAPFWjMPgcsX6KJ4p3eV8gqp/j3FU=; b=ArpfaGmF9479VeiFIloduuVNYgRBDKSqMTdQFSWVyDw0Q4zVyW/0/FUBHIJ2F6vo8c8KoB3q1NF6/N9er+KRvJ2d3QsVEmPvoAGw6PW8KqMVNaEbIllXRI53sog2DJGmV6+W/Ko+zhaoRgOE00PmyrwqaC+3O5J2IE5RYopHUXLrHq3Rrnva21VpNd583C2s2oRlkGCm6iqMPp89POBDWMVPWMMdlWcNT06vNVThY7zPbAc4aiR+y75CI6HKhD1ds3tVCKzuiuykNXxyxhQ/YwJfYnO72WDstQuVgzEdsCiBbTpKCTMCV6jeIqMpC3VpOMGJK+SKLB9JwblCj4v/OA== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=microsoft.com; dmarc=pass action=none header.from=microsoft.com; dkim=pass header.d=microsoft.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=selector2; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=oBot/PQOI/u19tbAPFWjMPgcsX6KJ4p3eV8gqp/j3FU=; b=LdpsCzalELUejQiRwIcDeheA2+55vC8FRkft+mEBfpa9ywjqNKW84aSsbUB+edZda/FZl0YUQIZQ2KxcFGRoE9KMMiCZTZgip3dr9fNZHUd86cntaOqLF6iWoQkwS1xYoQ4qa+SUMwMOzsyV6Q3vrm/31uVdsWnnYXLPDKp0XwY= Received: from CY4PR21MB0741.namprd21.prod.outlook.com (10.173.189.7) by CY4PR21MB0854.namprd21.prod.outlook.com (10.173.192.143) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.2451.18; Tue, 12 Nov 2019 21:20:27 +0000 Received: from CY4PR21MB0741.namprd21.prod.outlook.com ([fe80::8c0d:e8a3:4fb7:e083]) by CY4PR21MB0741.namprd21.prod.outlook.com ([fe80::8c0d:e8a3:4fb7:e083%9]) with mapi id 15.20.2451.018; Tue, 12 Nov 2019 21:20:27 +0000 From: Long Li To: Ming Lei Subject: RE: [PATCH 2/2] nvme-pci: poll IO after batch submission for multi-mapping queue Thread-Topic: [PATCH 2/2] nvme-pci: poll IO after batch submission for multi-mapping queue Thread-Index: AQHVlehiYcB/lSKxl0SzyAz+DwfVW6eGdeMAgAAtylCAADVHAIABOLmg Date: Tue, 12 Nov 2019 21:20:27 +0000 Message-ID: References: <20191108035508.26395-1-ming.lei@redhat.com> <20191108035508.26395-3-ming.lei@redhat.com> <20191111204446.GA26028@lst.de> <20191112023920.GD15079@ming.t460p> In-Reply-To: <20191112023920.GD15079@ming.t460p> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: authentication-results: spf=none (sender IP is ) smtp.mailfrom=longli@microsoft.com; x-originating-ip: [2001:4898:80e8:f:eddf:db5c:c6fe:798] x-ms-publictraffictype: Email x-ms-office365-filtering-ht: Tenant x-ms-office365-filtering-correlation-id: b8cd9b6b-9e78-4187-f75b-08d767b6238d x-ms-traffictypediagnostic: CY4PR21MB0854: x-microsoft-antispam-prvs: x-ms-oob-tlc-oobclassifiers: OLM:9508; x-forefront-prvs: 021975AE46 x-forefront-antispam-report: SFV:NSPM; SFS:(10019020)(39860400002)(376002)(396003)(136003)(366004)(346002)(199004)(189003)(64756008)(7696005)(71200400001)(5660300002)(71190400001)(9686003)(446003)(11346002)(102836004)(6436002)(6506007)(229853002)(256004)(55016002)(14444005)(46003)(6916009)(52536014)(76116006)(6116002)(66556008)(66946007)(2906002)(33656002)(66476007)(76176011)(6246003)(66446008)(8990500004)(74316002)(99286004)(10090500001)(86362001)(8676002)(186003)(81166006)(81156014)(7736002)(8936002)(305945005)(14454004)(476003)(10290500003)(25786009)(478600001)(486006)(4326008)(22452003)(316002)(54906003); DIR:OUT; SFP:1102; SCL:1; SRVR:CY4PR21MB0854; H:CY4PR21MB0741.namprd21.prod.outlook.com; FPR:; SPF:None; LANG:en; PTR:InfoNoRecords; A:1; MX:1; received-spf: None (protection.outlook.com: microsoft.com does not designate permitted sender hosts) x-ms-exchange-senderadcheck: 1 x-microsoft-antispam: BCL:0; x-microsoft-antispam-message-info: hk1Y+hyLEmRaCAjx+/KWVMi8olwL4MmceGn3GvlITrz8OiwMICDHCP62OIg23D0oTibrqQI+0OzAnX5tSHI3bKGFwibHUEpXGrHBM1+JEcsJnvqurtn8EGU6GmFztebFtOfykoOutzEQytcaBPddTQVh6DK2RMR1HqRS2Xm9BD+BTYYV8p7AmLI6uA0v9KUdIAMJEUIowmXOe9R6vZ6CSQvsS4rxeKxSY7BfAgdhUH73mEKUIOCgkHV217VpiKWZRnfSN4CD/iqNRAS/39seOCQvHmMQfjvrY2xRC68mdX9gcM6pyYjuKjPopASSEhTMRNZtEtVCifULlMrlJd1OOxsznGgOeuQ2G4NnKLOF9Cz98qWdtS02vZsfpn8KotQ2/EFDu8n3/cKmVahkVPG0DhU+6DXbPADRsOkfHHbELtLRyIb3QSwCsxbyZTnu+LUu x-ms-exchange-transport-forked: True MIME-Version: 1.0 X-OriginatorOrg: microsoft.com X-MS-Exchange-CrossTenant-Network-Message-Id: b8cd9b6b-9e78-4187-f75b-08d767b6238d X-MS-Exchange-CrossTenant-originalarrivaltime: 12 Nov 2019 21:20:27.3050 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 72f988bf-86f1-41af-91ab-2d7cd011db47 X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: F8GDUluSEHqR+wJawU1y0E75pC1/O+D+5fq6psbdSUaNzJOSWHEaeHXpjB8H2FKNHVjGJrU5+R3BTof6Xt9S/A== X-MS-Exchange-Transport-CrossTenantHeadersStamped: CY4PR21MB0854 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20191112_132036_041767_44ADEF1F X-CRM114-Status: GOOD ( 13.37 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Keith Busch , Jens Axboe , Christoph Hellwig , "linux-nvme@lists.infradead.org" , Sagi Grimberg Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org >Subject: Re: [PATCH 2/2] nvme-pci: poll IO after batch submission for multi- >mapping queue > >On Tue, Nov 12, 2019 at 12:33:50AM +0000, Long Li wrote: >> >From: Christoph Hellwig >> >Sent: Monday, November 11, 2019 12:45 PM >> >To: Ming Lei >> >Cc: linux-nvme@lists.infradead.org; Keith Busch ; >> >Jens Axboe ; Christoph Hellwig ; Sagi >> >Grimberg ; Long Li >> >Subject: Re: [PATCH 2/2] nvme-pci: poll IO after batch submission for >> >multi- mapping queue >> > >> >On Fri, Nov 08, 2019 at 11:55:08AM +0800, Ming Lei wrote: >> >> f9dde187fa92("nvme-pci: remove cq check after submission") removes >> >> cq check after submission, this change actually causes performance >> >> regression on some NVMe drive in which single nvmeq handles >> >> requests originated from more than one blk-mq sw queues(call it >> >> multi-mapping queue). >> > >> >> Follows test result done on Azure L80sv2 guest with NVMe drive( >> >> Microsoft Corporation Device b111). This guest has 80 CPUs and 10 >> >> numa nodes, and each NVMe drive supports 8 hw queues. >> > >> >Have you actually seen this on a real nvme drive as well? >> > >> >Note that it is kinda silly to limit queues like that in VMs, so I >> >really don't think we should optimize the driver for this particular case. >> >> I tested on an Azure L80s_v2 VM with newer Samsung P983 NVMe SSD >(with 32 hardware queues). Tests also showed soft lockup when 32 queues >are shared by 80 CPUs. >> > >BTW, do you see if this simple change makes a difference? Yes, I can confirm the patch fixed lockup on this VM configuration. There is also no performance regression. > >> The issue will likely show up if the number of NVMe hardware queues is >> less than the number of CPUs. I think this may be a likely >> configuration on a very large system. (e.g. the largest VM on Azure >> has 416 cores) >> > >'the number of NVMe hardware queues' above should be the number of >single NVMe drive. >I believe 32 hw queues is common, also poll queues may take several from >the total 32. >When interrupt handling on single CPU core can't catch up with NVMe's IO >handling, soft lockup could be triggered. Of course, there are lot kinds of >supported processors by Linux. > >Also when (nr_nvme_drives * nr_nvme_hw_queues) > nr_cpu_cores, one >same CPU can be assigned to handle more than 1 nvme IO queue interrupt >from different NVMe drive, the situation becomes worse. > > >Thanks, >Ming _______________________________________________ Linux-nvme mailing list Linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme