From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([209.51.188.92]:40498) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hJw06-0002NV-Ax for qemu-devel@nongnu.org; Fri, 26 Apr 2019 04:14:31 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hJw04-0001hG-0P for qemu-devel@nongnu.org; Fri, 26 Apr 2019 04:14:29 -0400 Received: from mx1.redhat.com ([209.132.183.28]:58076) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hJw03-0001Ua-Au for qemu-devel@nongnu.org; Fri, 26 Apr 2019 04:14:27 -0400 References: <5FF901C1-0AA5-4308-A65C-C448D0A2BA63@oracle.com> <20190305172905.GD13806@stefanha-x1.localdomain> <2D7F11D0-4A02-4A0F-961D-854240376B17@oracle.com> <20190401090724.GA643@stefanha-x1.localdomain> <60340EAF-4C85-4798-9999-34F1A37E2086@oracle.com> <898ef1d4-bfa2-9952-8ceb-f1282b85e29c@oracle.com> <20190416092042.GB32709@stefanha-x1.localdomain> <8E5AF770-69ED-4D44-8A25-B51344996D9E@oracle.com> <3F7E854A-3C1D-4204-8C35-893FC0614796@oracle.com> <20190423120453.GF32465@stefanha-x1.localdomain> From: Paolo Bonzini Message-ID: <44520476-d6a8-2e3f-1602-388e2e1e874e@redhat.com> Date: Fri, 26 Apr 2019 10:14:16 +0200 MIME-Version: 1.0 In-Reply-To: <20190423120453.GF32465@stefanha-x1.localdomain> Content-Type: text/plain; charset=windows-1252 Content-Language: en-US Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] Following up questions related to QEMU and I/O Thread List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Stefan Hajnoczi , Wei Li Cc: Stefan Hajnoczi , Dongli Zhang , qemu-devel@nongnu.org On 23/04/19 14:04, Stefan Hajnoczi wrote: >> In addition, does Virtio-scsi support Batch I/O Submission feature >> which may be able to increase the IOPS via reducing the number of >> system calls? > > I don't see obvious batching support in drivers/scsi/virtio_scsi.c. > The Linux block layer supports batching but I'm not sure if the SCSI > layer does. I think he's referring to QEMU, in which case yes, virtio-scsi does batch I/O submission. See virtio_scsi_handle_cmd_req_prepare and virtio_scsi_handle_cmd_req_submit in hw/scsi/virtio-scsi.c, they do blk_io_plug and blk_io_unplug in order to batch I/O requests from QEMU to the host kernel. Paolo 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=-0.9 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham 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 B23D8C43219 for ; Fri, 26 Apr 2019 08:15:16 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 21BEC2077B for ; Fri, 26 Apr 2019 08:15:16 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 21BEC2077B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([127.0.0.1]:42864 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hJw0p-0002i4-2l for qemu-devel@archiver.kernel.org; Fri, 26 Apr 2019 04:15:15 -0400 Received: from eggs.gnu.org ([209.51.188.92]:40498) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hJw06-0002NV-Ax for qemu-devel@nongnu.org; Fri, 26 Apr 2019 04:14:31 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hJw04-0001hG-0P for qemu-devel@nongnu.org; Fri, 26 Apr 2019 04:14:29 -0400 Received: from mx1.redhat.com ([209.132.183.28]:58076) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hJw03-0001Ua-Au for qemu-devel@nongnu.org; Fri, 26 Apr 2019 04:14:27 -0400 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 59A36C057F2C; Fri, 26 Apr 2019 08:14:21 +0000 (UTC) Received: from [10.36.112.23] (ovpn-112-23.ams2.redhat.com [10.36.112.23]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 7A3BA1001E7C; Fri, 26 Apr 2019 08:14:19 +0000 (UTC) To: Stefan Hajnoczi , Wei Li References: <5FF901C1-0AA5-4308-A65C-C448D0A2BA63@oracle.com> <20190305172905.GD13806@stefanha-x1.localdomain> <2D7F11D0-4A02-4A0F-961D-854240376B17@oracle.com> <20190401090724.GA643@stefanha-x1.localdomain> <60340EAF-4C85-4798-9999-34F1A37E2086@oracle.com> <898ef1d4-bfa2-9952-8ceb-f1282b85e29c@oracle.com> <20190416092042.GB32709@stefanha-x1.localdomain> <8E5AF770-69ED-4D44-8A25-B51344996D9E@oracle.com> <3F7E854A-3C1D-4204-8C35-893FC0614796@oracle.com> <20190423120453.GF32465@stefanha-x1.localdomain> From: Paolo Bonzini Openpgp: preference=signencrypt Autocrypt: addr=pbonzini@redhat.com; prefer-encrypt=mutual; keydata= mQHhBFRCcBIBDqDGsz4K0zZun3jh+U6Z9wNGLKQ0kSFyjN38gMqU1SfP+TUNQepFHb/Gc0E2 CxXPkIBTvYY+ZPkoTh5xF9oS1jqI8iRLzouzF8yXs3QjQIZ2SfuCxSVwlV65jotcjD2FTN04 hVopm9llFijNZpVIOGUTqzM4U55sdsCcZUluWM6x4HSOdw5F5Utxfp1wOjD/v92Lrax0hjiX DResHSt48q+8FrZzY+AUbkUS+Jm34qjswdrgsC5uxeVcLkBgWLmov2kMaMROT0YmFY6A3m1S P/kXmHDXxhe23gKb3dgwxUTpENDBGcfEzrzilWueOeUWiOcWuFOed/C3SyijBx3Av/lbCsHU Vx6pMycNTdzU1BuAroB+Y3mNEuW56Yd44jlInzG2UOwt9XjjdKkJZ1g0P9dwptwLEgTEd3Fo UdhAQyRXGYO8oROiuh+RZ1lXp6AQ4ZjoyH8WLfTLf5g1EKCTc4C1sy1vQSdzIRu3rBIjAvnC tGZADei1IExLqB3uzXKzZ1BZ+Z8hnt2og9hb7H0y8diYfEk2w3R7wEr+Ehk5NQsT2MPI2QBd wEv1/Aj1DgUHZAHzG1QN9S8wNWQ6K9DqHZTBnI1hUlkp22zCSHK/6FwUCuYp1zcAEQEAAbQj UGFvbG8gQm9uemluaSA8cGJvbnppbmlAcmVkaGF0LmNvbT6JAg0EEwECACMFAlRCcBICGwMH CwkIBwMCAQYVCAIJCgsEFgIDAQIeAQIXgAAKCRB+FRAMzTZpsbceDp9IIN6BIA0Ol7MoB15E 11kRz/ewzryFY54tQlMnd4xxfH8MTQ/mm9I482YoSwPMdcWFAKnUX6Yo30tbLiNB8hzaHeRj jx12K+ptqYbg+cevgOtbLAlL9kNgLLcsGqC2829jBCUTVeMSZDrzS97ole/YEez2qFpPnTV0 VrRWClWVfYh+JfzpXmgyhbkuwUxNFk421s4Ajp3d8nPPFUGgBG5HOxzkAm7xb1cjAuJ+oi/K CHfkuN+fLZl/u3E/fw7vvOESApLU5o0icVXeakfSz0LsygEnekDbxPnE5af/9FEkXJD5EoYG SEahaEtgNrR4qsyxyAGYgZlS70vkSSYJ+iT2rrwEiDlo31MzRo6Ba2FfHBSJ7lcYdPT7bbk9 AO3hlNMhNdUhoQv7M5HsnqZ6unvSHOKmReNaS9egAGdRN0/GPDWr9wroyJ65ZNQsHl9nXBqE AukZNr5oJO5vxrYiAuuTSd6UI/xFkjtkzltG3mw5ao2bBpk/V/YuePrJsnPFHG7NhizrxttB nTuOSCMo45pfHQ+XYd5K1+Cv/NzZFNWscm5htJ0HznY+oOsZvHTyGz3v91pn51dkRYN0otqr bQ4tlFFuVjArBZcapSIe6NV8C4cEiSS5AQ0EVEJxcwEIAK+nUrsUz3aP2aBjIrX3a1+C+39R nctpNIPcJjFJ/8WafRiwcEuLjbvJ/4kyM6K7pWUIQftl1P8Woxwb5nqL7zEFHh5I+hKS3haO 5pgco//V0tWBGMKinjqntpd4U4Dl299dMBZ4rRbPvmI8rr63sCENxTnHhTECyHdGFpqSzWzy 97rH68uqMpxbUeggVwYkYihZNd8xt1+lf7GWYNEO/QV8ar/qbRPG6PEfiPPHQd/sldGYavmd //o6TQLSJsvJyJDt7KxulnNT8Q2X/OdEuVQsRT5glLaSAeVAABcLAEnNgmCIGkX7TnQF8a6w gHGrZIR9ZCoKvDxAr7RP6mPeS9sAEQEAAYkDEgQYAQIACQUCVEJxcwIbAgEpCRB+FRAMzTZp scBdIAQZAQIABgUCVEJxcwAKCRC/+9JfeMeug/SlCACl7QjRnwHo/VzENWD9G2VpUOd9eRnS DZGQmPo6Mp3Wy8vL7snGFBfRseT9BevXBSkxvtOnUUV2YbyLmolAODqUGzUI8ViF339poOYN i6Ffek0E19IMQ5+CilqJJ2d5ZvRfaq70LA/Ly9jmIwwX4auvXrWl99/2wCkqnWZI+PAepkcX JRD4KY2fsvRi64/aoQmcxTiyyR7q3/52Sqd4EdMfj0niYJV0Xb9nt8G57Dp9v3Ox5JeWZKXS krFqy1qyEIypIrqcMbtXM7LSmiQ8aJRM4ZHYbvgjChJKR4PsKNQZQlMWGUJO4nVFSkrixc9R Z49uIqQK3b3ENB1QkcdMg9cxsB0Onih8zR+Wp1uDZXnz1ekto+EivLQLqvTjCCwLxxJafwKI bqhQ+hGR9jF34EFur5eWt9jJGloEPVv0GgQflQaE+rRGe+3f5ZDgRe5Y/EJVNhBhKcafcbP8 MzmLRh3UDnYDwaeguYmxuSlMdjFL96YfhRBXs8tUw6SO9jtCgBvoOIBDCxxAJjShY4KIvEpK b2hSNr8KxzelKKlSXMtB1bbHbQxiQcerAipYiChUHq1raFc3V0eOyCXK205rLtknJHhM5pfG 6taABGAMvJgm/MrVILIxvBuERj1FRgcgoXtiBmLEJSb7akcrRlqe3MoPTntSTNvNzAJmfWhd SvP0G1WDLolqvX0OtKMppI91AWVu72f1kolJg43wbaKpRJg1GMkKEI3H+jrrlTBrNl/8e20m TElPRDKzPiowmXeZqFSS1A6Azv0TJoo9as+lWF+P4zCXt40+Zhh5hdHO38EV7vFAVG3iuay6 7ToF8Uy7tgc3mdH98WQSmHcn/H5PFYk3xTP3KHB7b0FZPdFPQXBZb9+tJeZBi9gMqcjMch+Y R8dmTcQRQX14bm5nXlBF7VpSOPZMR392LY7wzAvRdhz7aeIUkdO7VelaspFk2nT7wOj1Y6uL nRxQlLkBDQRUQnHuAQgAx4dxXO6/Zun0eVYOnr5GRl76+2UrAAemVv9Yfn2PbDIbxXqLff7o yVJIkw4WdhQIIvvtu5zH24iYjmdfbg8iWpP7NqxUQRUZJEWbx2CRwkMHtOmzQiQ2tSLjKh/c HeyFH68xjeLcinR7jXMrHQK+UCEw6jqi1oeZzGvfmxarUmS0uRuffAb589AJW50kkQK9VD/9 QC2FJISSUDnRC0PawGSZDXhmvITJMdD4TjYrePYhSY4uuIV02v028TVAaYbIhxvDY0hUQE4r 8ZbGRLn52bEzaIPgl1p/adKfeOUeMReg/CkyzQpmyB1TSk8lDMxQzCYHXAzwnGi8WU9iuE1P 0wARAQABiQHzBBgBAgAJBQJUQnHuAhsMAAoJEH4VEAzNNmmxp1EOoJy0uZggJm7gZKeJ7iUp eX4eqUtqelUw6gU2daz2hE/jsxsTbC/w5piHmk1H1VWDKEM4bQBTuiJ0bfo55SWsUNN+c9hh IX+Y8LEe22izK3w7mRpvGcg+/ZRG4DEMHLP6JVsv5GMpoYwYOmHnplOzCXHvmdlW0i6SrMsB Dl9rw4AtIa6bRwWLim1lQ6EM3PWifPrWSUPrPcw4OLSwFk0CPqC4HYv/7ZnASVkR5EERFF3+ 6iaaVi5OgBd81F1TCvCX2BEyIDRZLJNvX3TOd5FEN+lIrl26xecz876SvcOb5SL5SKg9/rCB ufdPSjojkGFWGziHiFaYhbuI2E+NfWLJtd+ZvWAAV+O0d8vFFSvriy9enJ8kxJwhC0ECbSKF Y+W1eTIhMD3aeAKY90drozWEyHhENf4l/V+Ja5vOnW+gCDQkGt2Y1lJAPPSIqZKvHzGShdh8 DduC0U3xYkfbGAUvbxeepjgzp0uEnBXfPTy09JGpgWbg0w91GyfT/ujKaGd4vxG2Ei+MMNDm S1SMx7wu0evvQ5kT9NPzyq8R2GIhVSiAd2jioGuTjX6AZCFv3ToO53DliFMkVTecLptsXaes uUHgL9dKIfvpm+rNXRn9wAwGjk0X/A== Message-ID: <44520476-d6a8-2e3f-1602-388e2e1e874e@redhat.com> Date: Fri, 26 Apr 2019 10:14:16 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <20190423120453.GF32465@stefanha-x1.localdomain> Content-Type: text/plain; charset="UTF-8" Content-Language: en-US X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.32]); Fri, 26 Apr 2019 08:14:21 +0000 (UTC) Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-devel] Following up questions related to QEMU and I/O Thread X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Stefan Hajnoczi , qemu-devel@nongnu.org, Dongli Zhang Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Message-ID: <20190426081416.xvonVrIGPfGEHf_7HQLqpTfxfq6hpYcUInbBq3LPw-o@z> On 23/04/19 14:04, Stefan Hajnoczi wrote: >> In addition, does Virtio-scsi support Batch I/O Submission feature >> which may be able to increase the IOPS via reducing the number of >> system calls? > > I don't see obvious batching support in drivers/scsi/virtio_scsi.c. > The Linux block layer supports batching but I'm not sure if the SCSI > layer does. I think he's referring to QEMU, in which case yes, virtio-scsi does batch I/O submission. See virtio_scsi_handle_cmd_req_prepare and virtio_scsi_handle_cmd_req_submit in hw/scsi/virtio-scsi.c, they do blk_io_plug and blk_io_unplug in order to batch I/O requests from QEMU to the host kernel. Paolo