From patchwork Tue Jun 28 07:47:01 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Peter Lieven X-Patchwork-Id: 641392 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 3rdybY4WBmz9s9Y for ; Tue, 28 Jun 2016 17:48:25 +1000 (AEST) Received: from localhost ([::1]:34805 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bHnkt-00037S-IP for incoming@patchwork.ozlabs.org; Tue, 28 Jun 2016 03:48:23 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:45057) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bHnjj-0001so-3j for qemu-devel@nongnu.org; Tue, 28 Jun 2016 03:47:12 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bHnjd-0002Xb-VY for qemu-devel@nongnu.org; Tue, 28 Jun 2016 03:47:10 -0400 Received: from mx-v6.kamp.de ([2a02:248:0:51::16]:46858 helo=mx01.kamp.de) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bHnjd-0002XB-Lr for qemu-devel@nongnu.org; Tue, 28 Jun 2016 03:47:05 -0400 Received: (qmail 22192 invoked by uid 89); 28 Jun 2016 07:47:03 -0000 Received: from [195.62.97.28] by client-16-kamp (envelope-from , uid 89) with qmail-scanner-2010/03/19-MF (clamdscan: 0.99.2/21803. hbedv: 8.3.40.44/7.12.99.34. avast: 1.2.2/16062701. spamassassin: 3.4.1. Clear:RC:1(195.62.97.28):. Processed in 0.053676 secs); 28 Jun 2016 07:47:03 -0000 Received: from smtp.kamp.de (HELO submission.kamp.de) ([195.62.97.28]) by mx01.kamp.de with ESMTPS (DHE-RSA-AES256-GCM-SHA384 encrypted); 28 Jun 2016 07:47:02 -0000 X-GL_Whitelist: yes Received: (qmail 29453 invoked from network); 28 Jun 2016 07:47:02 -0000 Received: from lieven-pc.kamp-intra.net (HELO ?172.21.12.60?) (pl@kamp.de@::ffff:172.21.12.60) by submission.kamp.de with ESMTPS (DHE-RSA-AES128-SHA encrypted) ESMTPA; 28 Jun 2016 07:47:02 -0000 To: Cornelia Huck , "Michael S. Tsirkin" References: <5770F58F.2080402@kamp.de> <20160627170938.04a7a13c.cornelia.huck@de.ibm.com> <20160628100152-mutt-send-email-mst@redhat.com> <20160628094245.0fefc484.cornelia.huck@de.ibm.com> From: Peter Lieven Message-ID: <57722B75.9090406@kamp.de> Date: Tue, 28 Jun 2016 09:47:01 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.8.0 MIME-Version: 1.0 In-Reply-To: <20160628094245.0fefc484.cornelia.huck@de.ibm.com> X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 2a02:248:0:51::16 Subject: Re: [Qemu-devel] Regression: virtio-pci: convert to ioeventfd callbacks 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: famz@redhat.com, "qemu-devel@nongnu.org" , stefanha@redhat.com Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" Am 28.06.2016 um 09:42 schrieb Cornelia Huck: > On Tue, 28 Jun 2016 10:03:21 +0300 > "Michael S. Tsirkin" wrote: > >> I notice cleanup is a bit weird: >> >> virtio_queue_set_host_notifier_fd_handler(vq, false, false); >> k->ioeventfd_assign(proxy, notifier, n, assign); >> event_notifier_cleanup(notifier); >> >> I think virtio_queue_set_host_notifier_fd_handler should happen >> after ioeventfd_assign for symmetry with init? > Looking at the pre-rework code, ccw used the order now in common code, > while pci and mmio used the order you suggest. > > "Switch the handler back, then unassign the transport's ioeventfd > backing" made more sense to me (regardless of symmetry) - but we might > lose a notification? > > Peter: Can you check whether your problem goes away if you switch the > two lines around? > The problem goes away, but its horribly slow. Maybe the lost notifications you were thinking off. Peter diff --git a/hw/virtio/virtio-bus.c b/hw/virtio/virtio-bus.c index 1313760..7924a59 100644 --- a/hw/virtio/virtio-bus.c +++ b/hw/virtio/virtio-bus.c @@ -176,9 +176,9 @@ static int set_host_notifier_internal(DeviceState *proxy, VirtioBusState *bus, return r; } } else { - virtio_queue_set_host_notifier_fd_handler(vq, false, false); k->ioeventfd_assign(proxy, notifier, n, assign); event_notifier_cleanup(notifier); + virtio_queue_set_host_notifier_fd_handler(vq, false, false); } return r; }