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Diffstat (limited to 'qemu/docs/virtio-balloon-stats.txt')
| -rw-r--r-- | qemu/docs/virtio-balloon-stats.txt | 105 |
1 files changed, 0 insertions, 105 deletions
diff --git a/qemu/docs/virtio-balloon-stats.txt b/qemu/docs/virtio-balloon-stats.txt deleted file mode 100644 index edff5f22a..000000000 --- a/qemu/docs/virtio-balloon-stats.txt +++ /dev/null @@ -1,105 +0,0 @@ -virtio balloon memory statistics -================================ - -The virtio balloon driver supports guest memory statistics reporting. These -statistics are available to QEMU users as QOM (QEMU Object Model) device -properties via a polling mechanism. - -Before querying the available stats, clients first have to enable polling. -This is done by writing a time interval value (in seconds) to the -guest-stats-polling-interval property. This value can be: - - > 0 enables polling in the specified interval. If polling is already - enabled, the polling time interval is changed to the new value - - 0 disables polling. Previous polled statistics are still valid and - can be queried. - -Once polling is enabled, the virtio-balloon device in QEMU will start -polling the guest's balloon driver for new stats in the specified time -interval. - -To retrieve those stats, clients have to query the guest-stats property, -which will return a dictionary containing: - - o A key named 'stats', containing all available stats. If the guest - doesn't support a particular stat, or if it couldn't be retrieved, - its value will be -1. Currently, the following stats are supported: - - - stat-swap-in - - stat-swap-out - - stat-major-faults - - stat-minor-faults - - stat-free-memory - - stat-total-memory - - 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. The value is 0 if the guest - has not updated the stats (yet). - -It's also important to note the following: - - - Previously polled statistics remain available even if the polling is - later disabled - - - As noted above, if a guest doesn't support a particular stat its value - will always be -1. However, it's also possible that a guest temporarily - couldn't update one or even all stats. If this happens, just wait for - the next update - - - 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, 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 - respond to the request the timer will never be re-armed, which has - the same effect as disabling polling - -Here are a few examples. QEMU is started with '-balloon virtio', which -generates '/machine/peripheral-anon/device[1]' as the QOM path for the -balloon device. - -Enable polling with 2 seconds interval: - -{ "execute": "qom-set", - "arguments": { "path": "/machine/peripheral-anon/device[1]", - "property": "guest-stats-polling-interval", "value": 2 } } - -{ "return": {} } - -Change polling to 10 seconds: - -{ "execute": "qom-set", - "arguments": { "path": "/machine/peripheral-anon/device[1]", - "property": "guest-stats-polling-interval", "value": 10 } } - -{ "return": {} } - -Get stats: - -{ "execute": "qom-get", - "arguments": { "path": "/machine/peripheral-anon/device[1]", - "property": "guest-stats" } } -{ - "return": { - "stats": { - "stat-swap-out": 0, - "stat-free-memory": 844943360, - "stat-minor-faults": 219028, - "stat-major-faults": 235, - "stat-total-memory": 1044406272, - "stat-swap-in": 0 - }, - "last-update": 1358529861 - } -} - -Disable polling: - -{ "execute": "qom-set", - "arguments": { "path": "/machine/peripheral-anon/device[1]", - "property": "stats-polling-interval", "value": 0 } } - -{ "return": {} } |