From patchwork Fri Sep 9 20:34:29 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Michael S. Tsirkin" X-Patchwork-Id: 9324355 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 0B9D260231 for ; Fri, 9 Sep 2016 20:43:41 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id F06252A019 for ; Fri, 9 Sep 2016 20:43:40 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id E4FD02A01D; Fri, 9 Sep 2016 20:43:40 +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=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 8E9DA2A019 for ; Fri, 9 Sep 2016 20:43:40 +0000 (UTC) Received: from localhost ([::1]:60127 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1biSeB-0005eD-Jn for patchwork-qemu-devel@patchwork.kernel.org; Fri, 09 Sep 2016 16:43:39 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:55879) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1biSVM-00066P-Rl for qemu-devel@nongnu.org; Fri, 09 Sep 2016 16:34:36 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1biSVK-0005Sy-SJ for qemu-devel@nongnu.org; Fri, 09 Sep 2016 16:34:31 -0400 Received: from mx1.redhat.com ([209.132.183.28]:51192) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1biSVK-0005Sq-Mb for qemu-devel@nongnu.org; Fri, 09 Sep 2016 16:34:30 -0400 Received: from int-mx10.intmail.prod.int.phx2.redhat.com (int-mx10.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 498BF3710C4; Fri, 9 Sep 2016 20:34:30 +0000 (UTC) Received: from redhat.com (vpn-62-83.rdu2.redhat.com [10.10.62.83]) by int-mx10.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with SMTP id u89KYTA2032643; Fri, 9 Sep 2016 16:34:29 -0400 Date: Fri, 9 Sep 2016 23:34:29 +0300 From: "Michael S. Tsirkin" To: qemu-devel@nongnu.org Message-ID: <1473453215-7556-12-git-send-email-mst@redhat.com> References: <1473453215-7556-1-git-send-email-mst@redhat.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1473453215-7556-1-git-send-email-mst@redhat.com> X-Mutt-Fcc: =sent X-Scanned-By: MIMEDefang 2.68 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Fri, 09 Sep 2016 20:34:30 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PULL 11/14] vhost: don't set vring call if no vector 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: Peter Maydell , Jason Wang Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" X-Virus-Scanned: ClamAV using ClamSMTP From: Jason Wang We used to set vring call fd unconditionally even if guest driver does not use MSIX for this vritqueue at all. This will cause lots of unnecessary userspace access and other checks for drivers does not use interrupt at all (e.g virtio-net pmd). So check and clean vring call fd if guest does not use any vector for this virtqueue at all. Perf diffs (on rx) shows lots of cpus wasted on vhost_signal() were saved: # 28.12% -27.82% [vhost] [k] vhost_signal 14.44% -1.69% [kernel.vmlinux] [k] copy_user_generic_string 7.05% +1.53% [kernel.vmlinux] [k] __free_page_frag 6.51% +5.53% [vhost] [k] vhost_get_vq_desc ... Pktgen tests shows 15.8% improvement on rx pps and 6.5% on tx pps. Before: RX 2.08Mpps TX 1.35Mpps After: RX 2.41Mpps TX 1.44Mpps Signed-off-by: Jason Wang Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin --- hw/virtio/vhost.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c index 3d0c807..bd051ab 100644 --- a/hw/virtio/vhost.c +++ b/hw/virtio/vhost.c @@ -822,6 +822,9 @@ static int vhost_virtqueue_start(struct vhost_dev *dev, struct vhost_virtqueue *vq, unsigned idx) { + BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev))); + VirtioBusState *vbus = VIRTIO_BUS(qbus); + VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(vbus); hwaddr s, l, a; int r; int vhost_vq_index = dev->vhost_ops->vhost_get_vq_index(dev, idx); @@ -912,8 +915,19 @@ static int vhost_virtqueue_start(struct vhost_dev *dev, vhost_virtqueue_mask(dev, vdev, idx, false); } + if (k->query_guest_notifiers && + k->query_guest_notifiers(qbus->parent) && + virtio_queue_vector(vdev, idx) == VIRTIO_NO_VECTOR) { + file.fd = -1; + r = dev->vhost_ops->vhost_set_vring_call(dev, &file); + if (r) { + goto fail_vector; + } + } + return 0; +fail_vector: fail_kick: fail_alloc: cpu_physical_memory_unmap(vq->ring, virtio_queue_get_ring_size(vdev, idx),