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| author | Ján Tomko <jtomko@redhat.com> | 2014-05-21 11:03:47 +0200 |
|---|---|---|
| committer | Michael S. Tsirkin <mst@redhat.com> | 2014-05-25 12:46:58 +0300 |
| commit | 38dbd48b247ebe05bdc6ef52ccdc60cc21274877 (patch) | |
| tree | e3294ac81369b393769a51b9d41fb4c9384a9d3e /docs | |
| parent | 7c8b7248261bfa5e54eff1715b699caa8b3f1d77 (diff) | |
| download | qemu-38dbd48b247ebe05bdc6ef52ccdc60cc21274877.tar.gz | |
virtio-balloon: return empty data when no stats are available
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 <jtomko@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Diffstat (limited to 'docs')
| -rw-r--r-- | docs/virtio-balloon-stats.txt | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/docs/virtio-balloon-stats.txt b/docs/virtio-balloon-stats.txt index f74612f468..edff5f22a8 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 |