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Re: [Qemu-devel] [PATCH] virtio-balloon: return empty data when no stats
From: |
Luiz Capitulino |
Subject: |
Re: [Qemu-devel] [PATCH] virtio-balloon: return empty data when no stats are available |
Date: |
Tue, 20 May 2014 15:13:22 -0400 |
On Mon, 19 May 2014 08:41:21 +0200
Ján Tomko <address@hidden> wrote:
> 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
>
> Signed-off-by: Ján Tomko <address@hidden>
> ---
> hw/virtio/virtio-balloon.c | 7 ++-----
> 1 file changed, 2 insertions(+), 5 deletions(-)
>
> diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
> index 971a921..6661c53 100644
> --- a/hw/virtio/virtio-balloon.c
> +++ b/hw/virtio/virtio-balloon.c
> @@ -111,11 +111,6 @@ 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, errp);
> visit_type_int(v, &s->stats_last_update, "last-update", errp);
>
> @@ -361,6 +356,8 @@ 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);
>
Looks good to me, but I have some comments:
- I'm assuming you tested this against libivrt, right? It's good to add
a comment in the changelog mentioning that
- You have to update the documentation in docs/virtio-balloon-stats.txt
as well. There are two sections to update, the one describing the last-update
key (where you should mention what it means when last-update=0) and the
section saying that polling can be enabled even when the guest doesn't have
stats support (I'd mention that last-update=0 for that case)
- Please, rebase on top of latest master