From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:57128) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eZiuB-0004pr-9d for qemu-devel@nongnu.org; Thu, 11 Jan 2018 14:52:52 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eZiuA-0008Sx-ER for qemu-devel@nongnu.org; Thu, 11 Jan 2018 14:52:51 -0500 Received: from mx1.redhat.com ([209.132.183.28]:43034) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1eZiuA-0008OP-7t for qemu-devel@nongnu.org; Thu, 11 Jan 2018 14:52:50 -0500 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 9C0F468A9 for ; Thu, 11 Jan 2018 19:52:43 +0000 (UTC) Date: Thu, 11 Jan 2018 21:52:39 +0200 From: "Michael S. Tsirkin" Message-ID: <20180111215210-mutt-send-email-mst@kernel.org> References: <1515665816-10313-1-git-send-email-ghammer@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1515665816-10313-1-git-send-email-ghammer@redhat.com> Subject: Re: [Qemu-devel] [PATCH] virtio: improve virtio devices initialization time List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Gal Hammer Cc: qemu-devel@nongnu.org On Thu, Jan 11, 2018 at 12:16:56PM +0200, Gal Hammer wrote: > The loading time of a VM is quite significant when its virtio > devices uses a large amount of virt-queues (e.g. a virtio-serial > device with max_ports=511). Most of the time is spend in the > creation of all the required event notifiers (ioeventfd and memory > regions). > > This patch pack all the changes to the memory regions in a > single memory transaction. > > Reported-by: Sitong Liu > Reported-by: Xiaoling Gao > Signed-off-by: Gal Hammer Nice patch! Any timing numbers to share before/after? > --- > hw/virtio/virtio.c | 11 +++++++++++ > 1 file changed, 11 insertions(+) > > diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c > index ad564b0..8d8d93d 100644 > --- a/hw/virtio/virtio.c > +++ b/hw/virtio/virtio.c > @@ -2574,6 +2574,7 @@ static int virtio_device_start_ioeventfd_impl(VirtIODevice *vdev) > VirtioBusState *qbus = VIRTIO_BUS(qdev_get_parent_bus(DEVICE(vdev))); > int n, r, err; > > + memory_region_transaction_begin(); > for (n = 0; n < VIRTIO_QUEUE_MAX; n++) { > VirtQueue *vq = &vdev->vq[n]; > if (!virtio_queue_get_num(vdev, n)) { > @@ -2596,6 +2597,7 @@ static int virtio_device_start_ioeventfd_impl(VirtIODevice *vdev) > } > event_notifier_set(&vq->host_notifier); > } > + memory_region_transaction_commit(); > return 0; > > assign_error: > @@ -2609,6 +2611,7 @@ assign_error: > r = virtio_bus_set_host_notifier(qbus, n, false); > assert(r >= 0); > } > + memory_region_transaction_commit(); > return err; > } > > @@ -2625,6 +2628,7 @@ static void virtio_device_stop_ioeventfd_impl(VirtIODevice *vdev) > VirtioBusState *qbus = VIRTIO_BUS(qdev_get_parent_bus(DEVICE(vdev))); > int n, r; > > + memory_region_transaction_begin(); > for (n = 0; n < VIRTIO_QUEUE_MAX; n++) { > VirtQueue *vq = &vdev->vq[n]; > > @@ -2632,6 +2636,13 @@ static void virtio_device_stop_ioeventfd_impl(VirtIODevice *vdev) > continue; > } > event_notifier_set_handler(&vq->host_notifier, NULL); > + } > + memory_region_transaction_commit(); > + > + for (n = 0; n < VIRTIO_QUEUE_MAX; n++) { > + if (!virtio_queue_get_num(vdev, n)) { > + continue; > + } > r = virtio_bus_set_host_notifier(qbus, n, false); > assert(r >= 0); > } > -- > 2.7.5