From patchwork Wed May 21 09:03:47 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?J=C3=A1n_Tomko?= X-Patchwork-Id: 351021 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 D5EE514008A for ; Wed, 21 May 2014 19:04:23 +1000 (EST) Received: from localhost ([::1]:58070 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Wn2Rh-00037i-Np for incoming@patchwork.ozlabs.org; Wed, 21 May 2014 05:04:21 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:55354) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Wn2RO-0002oc-Bn for qemu-devel@nongnu.org; Wed, 21 May 2014 05:04:07 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Wn2RJ-00070z-IP for qemu-devel@nongnu.org; Wed, 21 May 2014 05:04:02 -0400 Received: from mx1.redhat.com ([209.132.183.28]:31763) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Wn2RJ-00070v-9k for qemu-devel@nongnu.org; Wed, 21 May 2014 05:03:57 -0400 Received: from int-mx01.intmail.prod.int.phx2.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id s4L93saT010290 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Wed, 21 May 2014 05:03:55 -0400 Received: from snc.brq.redhat.com (dhcp-27-243.brq.redhat.com [10.34.27.243]) by int-mx01.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id s4L93q2M003771; Wed, 21 May 2014 05:03:53 -0400 From: =?UTF-8?q?J=C3=A1n=20Tomko?= To: qemu-devel@nongnu.org Date: Wed, 21 May 2014 11:03:47 +0200 Message-Id: <337a4c88f373a56ca30698bf1f8772467ddb347d.1400662668.git.jtomko@redhat.com> MIME-Version: 1.0 MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.67 on 10.5.11.11 X-MIME-Autoconverted: from 8bit to quoted-printable by mx1.redhat.com id s4L93saT010290 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x X-Received-From: 209.132.183.28 Cc: mst@redhat.com, aliguori@amazon.com, lcapitulino@redhat.com Subject: [Qemu-devel] [PATCH v2] virtio-balloon: return empty data when no stats are available X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org If the guest hasn't updated the stats yet, instead of returning an error, return '-1' for the stats and '0' as 'last-update'. This lets applications ignore this without parsing the error message. Related libvirt patch and discussion: https://www.redhat.com/archives/libvir-list/2014-May/msg00460.html Tested against current upstream libvirt - stat reporting works and it no longer logs errors when the stats are queried on domain startup. (Note: libvirt doesn't use the last-update field for anything yet) Signed-off-by: Ján Tomko Reviewed-by: Eric Blake --- v1: https://lists.gnu.org/archive/html/qemu-devel/2014-05/msg03643.html Reviewed-by: Eric Blake v2: rebased added documentation changes mentioned testing in the commit message docs/virtio-balloon-stats.txt | 5 +++-- hw/virtio/virtio-balloon.c | 7 ++----- 2 files changed, 5 insertions(+), 7 deletions(-) diff --git a/docs/virtio-balloon-stats.txt b/docs/virtio-balloon-stats.txt index f74612f..edff5f2 100644 --- a/docs/virtio-balloon-stats.txt +++ b/docs/virtio-balloon-stats.txt @@ -35,7 +35,8 @@ which will return a dictionary containing: o A key named last-update, which contains the last stats update timestamp in seconds. Since this timestamp is generated by the host, - a buggy guest can't influence its value + a buggy guest can't influence its value. The value is 0 if the guest + has not updated the stats (yet). It's also important to note the following: @@ -49,7 +50,7 @@ It's also important to note the following: - Polling can be enabled even if the guest doesn't have stats support or the balloon driver wasn't loaded in the guest. If this is the case - and stats are queried, an error will be returned + and stats are queried, last-update will be 0. - The polling timer is only re-armed when the guest responds to the statistics request. This means that if a (buggy) guest doesn't ever diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c index bf2b588..22cd52e 100644 --- a/hw/virtio/virtio-balloon.c +++ b/hw/virtio/virtio-balloon.c @@ -112,11 +112,6 @@ static void balloon_stats_get_all(Object *obj, struct Visitor *v, VirtIOBalloon *s = opaque; int i; - if (!s->stats_last_update) { - error_setg(errp, "guest hasn't updated any stats yet"); - return; - } - visit_start_struct(v, NULL, "guest-stats", name, 0, &err); if (err) { goto out; @@ -378,6 +373,8 @@ static void virtio_balloon_device_realize(DeviceState *dev, Error **errp) s->dvq = virtio_add_queue(vdev, 128, virtio_balloon_handle_output); s->svq = virtio_add_queue(vdev, 128, virtio_balloon_receive_stats); + reset_stats(s); + register_savevm(dev, "virtio-balloon", -1, 1, virtio_balloon_save, virtio_balloon_load, s);