From patchwork Wed Mar 27 10:36:33 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dongli Zhang X-Patchwork-Id: 10873195 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 16958186E for ; Wed, 27 Mar 2019 10:33:02 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 061FF28CA8 for ; Wed, 27 Mar 2019 10:33:02 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id EDD0528CBB; Wed, 27 Mar 2019 10:33:01 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 95E4728CA8 for ; Wed, 27 Mar 2019 10:33:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732789AbfC0Kct (ORCPT ); Wed, 27 Mar 2019 06:32:49 -0400 Received: from aserp2130.oracle.com ([141.146.126.79]:39018 "EHLO aserp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727328AbfC0Kct (ORCPT ); Wed, 27 Mar 2019 06:32:49 -0400 Received: from pps.filterd (aserp2130.oracle.com [127.0.0.1]) by aserp2130.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x2RADXc5043835; Wed, 27 Mar 2019 10:32:40 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=from : to : cc : subject : date : message-id; s=corp-2018-07-02; bh=1tW29WhXsQZtDQQ0Z2G78kTtwyNKbuql7nWIeE0goBk=; b=QZAdvwXJ/Xi0U5zgiZuGZxvKOZ32XprVxbBz003PbKreRkziqZ5xQnyb247EbscXhM/q A+FlBFrl2DovzdIvZyisqKp8gyzoOvQG+B/hCDwlnVNt8FF52p2cbXoT9yA+6T8sUYJA +KtpuaZpWau5NgreWJsBxmyjO0a1FKVUXnoczkv8Q6+sHH3MoPdvgyKPqZVs8EWUOCN8 Ob7o+XL7V5/RI2YIYqGUg9tU5RwKnWGAfZzeJl3zGVzf78SUWUgt33N5Uid9NObmsvtb pKu7WZaKP3ITLcLLvi8mYUJfpOz9OakMHNfQtkoZUH+UYy1VpRNYXGfrqWxBf5/TiqLM nQ== Received: from aserv0021.oracle.com (aserv0021.oracle.com [141.146.126.233]) by aserp2130.oracle.com with ESMTP id 2re6g0yns1-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 27 Mar 2019 10:32:40 +0000 Received: from userv0122.oracle.com (userv0122.oracle.com [156.151.31.75]) by aserv0021.oracle.com (8.14.4/8.14.4) with ESMTP id x2RAWdoW019899 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 27 Mar 2019 10:32:40 GMT Received: from abhmp0016.oracle.com (abhmp0016.oracle.com [141.146.116.22]) by userv0122.oracle.com (8.14.4/8.14.4) with ESMTP id x2RAWcp9001129; Wed, 27 Mar 2019 10:32:38 GMT Received: from linux.cn.oracle.com (/10.182.69.106) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Wed, 27 Mar 2019 03:32:37 -0700 From: Dongli Zhang To: linux-scsi@vger.kernel.org, virtualization@lists.linux-foundation.org, linux-block@vger.kernel.org Cc: mst@redhat.com, jasowang@redhat.com, axboe@kernel.dk, jejb@linux.ibm.com, martin.petersen@oracle.com, cohuck@redhat.com, linux-kernel@vger.kernel.org Subject: [PATCH 0/2] Limit number of hw queues by nr_cpu_ids for virtio-blk and virtio-scsi Date: Wed, 27 Mar 2019 18:36:33 +0800 Message-Id: <1553682995-5682-1-git-send-email-dongli.zhang@oracle.com> X-Mailer: git-send-email 2.7.4 X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9207 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=686 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1903270074 Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP When tag_set->nr_maps is 1, the block layer limits the number of hw queues by nr_cpu_ids. No matter how many hw queues are use by virtio-blk/virtio-scsi, as they both have (tag_set->nr_maps == 1), they can use at most nr_cpu_ids hw queues. In addition, specifically for pci scenario, when the 'num-queues' specified by qemu is more than maxcpus, virtio-blk/virtio-scsi would not be able to allocate more than maxcpus vectors in order to have a vector for each queue. As a result, they fall back into MSI-X with one vector for config and one shared for queues. Considering above reasons, this patch set limits the number of hw queues used by nr_cpu_ids for both virtio-blk and virtio-scsi. ------------------------------------------------------------- Here is test result of virtio-scsi: qemu cmdline: -smp 2,maxcpus=4, \ -device virtio-scsi-pci,id=scsi0,num_queues=8, \ -device scsi-hd,drive=drive0,bus=scsi0.0,channel=0,scsi-id=0,lun=0, \ -drive file=test.img,if=none,id=drive0 Although maxcpus=4 and num_queues=8, 4 queues are used while 2 interrupts are allocated. # cat /proc/interrupts ... ... 24: 0 0 PCI-MSI 65536-edge virtio0-config 25: 0 369 PCI-MSI 65537-edge virtio0-virtqueues ... ... # /sys/block/sda/mq/ 0 1 2 3 ------> 4 queues although qemu sets num_queues=8 With the patch set, there is per-queue interrupt. # cat /proc/interrupts 24: 0 0 PCI-MSI 65536-edge virtio0-config 25: 0 0 PCI-MSI 65537-edge virtio0-control 26: 0 0 PCI-MSI 65538-edge virtio0-event 27: 296 0 PCI-MSI 65539-edge virtio0-request 28: 0 139 PCI-MSI 65540-edge virtio0-request 29: 0 0 PCI-MSI 65541-edge virtio0-request 30: 0 0 PCI-MSI 65542-edge virtio0-request # ls /sys/block/sda/mq 0 1 2 3 ------------------------------------------------------------- Here is test result of virtio-blk: qemu cmdline: -smp 2,maxcpus=4, -device virtio-blk-pci,drive=drive-virtio-disk0,id=virtio-disk0,num-queues=8 -drive test.img,format=raw,if=none,id=drive-virtio-disk0 Although maxcpus=4 and num-queues=8, 4 queues are used while 2 interrupts are allocated. # cat /proc/interrupts ... ... 24: 0 0 PCI-MSI 65536-edge virtio0-config 25: 0 65 PCI-MSI 65537-edge virtio0-virtqueues ... ... # ls /sys/block/vda/mq 0 1 2 3 -------> 4 queues although qemu sets num_queues=8 With the patch set, there is per-queue interrupt. # cat /proc/interrupts 24: 0 0 PCI-MSI 65536-edge virtio0-config 25: 64 0 PCI-MSI 65537-edge virtio0-req.0 26: 0 10290 PCI-MSI 65538-edge virtio0-req.1 27: 0 0 PCI-MSI 65539-edge virtio0-req.2 28: 0 0 PCI-MSI 65540-edge virtio0-req.3 # ls /sys/block/vda/mq/ 0 1 2 3 Reference: https://lore.kernel.org/lkml/e4afe4c5-0262-4500-aeec-60f30734b4fc@default/ Thank you very much! Dongli Zhang