The statistics are now available through device properties via a
polling mechanism. First a client has to enable polling, then it
can query available stats.
Polling is enabled by setting an update interval (in seconds)
to a property named guest-stats-polling-interval, like this:
{ "execute": "qom-set",
"arguments": { "path": "/machine/peripheral-anon/device[1]",
"property": "guest-stats-polling-interval", "value": 4 } }
Then the available stats can be retrieved by querying the
guest-stats property. The returned object is a dict containing
all available stats. Example:
{ "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
}
}
Please, check the next commit for full documentation.
Signed-off-by: Luiz Capitulino <address@hidden>
Reviewed-by: Eric Blake <address@hidden>
---
hw/virtio-balloon.c | 151 +++++++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 150 insertions(+), 1 deletion(-)
diff --git a/hw/virtio-balloon.c b/hw/virtio-balloon.c
index 2520cba..c0a7902 100644
--- a/hw/virtio-balloon.c
+++ b/hw/virtio-balloon.c
@@ -14,6 +14,7 @@
*/
#include "qemu/iov.h"
+#include "qemu/timer.h"
#include "qemu-common.h"
#include "virtio.h"
#include "pc.h"
@@ -22,6 +23,7 @@
#include "virtio-balloon.h"
#include "sysemu/kvm.h"
#include "exec/address-spaces.h"
+#include "qapi/visitor.h"
#if defined(__linux__)
#include <sys/mman.h>
@@ -36,6 +38,9 @@ typedef struct VirtIOBalloon
uint64_t stats[VIRTIO_BALLOON_S_NR];
VirtQueueElement stats_vq_elem;
size_t stats_vq_offset;
+ QEMUTimer *stats_timer;
+ int64_t stats_last_update;
+ int64_t stats_poll_interval;
DeviceState *qdev;
} VirtIOBalloon;
@@ -53,6 +58,16 @@ static void balloon_page(void *addr, int deflate)
#endif
}
+static const char *balloon_stat_names[] = {
+ [VIRTIO_BALLOON_S_SWAP_IN] = "stat-swap-in",
+ [VIRTIO_BALLOON_S_SWAP_OUT] = "stat-swap-out",
+ [VIRTIO_BALLOON_S_MAJFLT] = "stat-major-faults",
+ [VIRTIO_BALLOON_S_MINFLT] = "stat-minor-faults",
+ [VIRTIO_BALLOON_S_MEMFREE] = "stat-free-memory",
+ [VIRTIO_BALLOON_S_MEMTOT] = "stat-total-memory",
+ [VIRTIO_BALLOON_S_NR] = NULL
+};
+
/*
* reset_stats - Mark all items in the stats array as unset
*
@@ -67,6 +82,118 @@ static inline void reset_stats(VirtIOBalloon *dev)
for (i = 0; i < VIRTIO_BALLOON_S_NR; dev->stats[i++] = -1);
}
+static bool balloon_stats_supported(const VirtIOBalloon *s)
+{
+ return s->vdev.guest_features & (1 << VIRTIO_BALLOON_F_STATS_VQ);
+}
+
+static bool balloon_stats_enabled(const VirtIOBalloon *s)
+{
+ return s->stats_poll_interval > 0;
+}
+
+static void balloon_stats_destroy_timer(VirtIOBalloon *s)
+{
+ if (balloon_stats_enabled(s)) {
+ qemu_del_timer(s->stats_timer);
+ qemu_free_timer(s->stats_timer);
+ s->stats_timer = NULL;
+ s->stats_poll_interval = 0;
+ }
+}
+
+static void balloon_stats_change_timer(VirtIOBalloon *s, int secs)
+{
+ qemu_mod_timer(s->stats_timer, qemu_get_clock_ms(vm_clock) + secs * 1000);
+}
+
+static void balloon_stats_poll_cb(void *opaque)
+{
+ VirtIOBalloon *s = opaque;
+
+ if (!balloon_stats_supported(s)) {
+ /* re-schedule */
+ balloon_stats_change_timer(s, s->stats_poll_interval);
+ return;
+ }
+
+ virtqueue_push(s->svq, &s->stats_vq_elem, s->stats_vq_offset);
+ virtio_notify(&s->vdev, s->svq);
+}
+
+static void balloon_stats_get_all(Object *obj, struct Visitor *v,
+ void *opaque, const char *name, Error **errp)
+{
+ 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);
+
+ visit_start_struct(v, NULL, NULL, "stats", 0, errp);
+ for (i = 0; i < VIRTIO_BALLOON_S_NR; i++) {
+ visit_type_int64(v, (int64_t *) &s->stats[i], balloon_stat_names[i],
+ errp);
+ }
+ visit_end_struct(v, errp);
+
+ visit_end_struct(v, errp);
+}
+
+static void balloon_stats_get_poll_interval(Object *obj, struct Visitor *v,
+ void *opaque, const char *name,
+ Error **errp)
+{
+ VirtIOBalloon *s = opaque;
+ visit_type_int(v, &s->stats_poll_interval, name, errp);
+}
+
+static void balloon_stats_set_poll_interval(Object *obj, struct Visitor *v,
+ void *opaque, const char *name,
+ Error **errp)
+{
+ VirtIOBalloon *s = opaque;
+ int64_t value;
+
+ visit_type_int(v, &value, name, errp);
+ if (error_is_set(errp)) {
+ return;
+ }
+
+ if (value < 0) {
+ error_setg(errp, "timer value must be greater than zero");
+ return;
+ }
+
+ if (value == s->stats_poll_interval) {
+ return;
+ }
+
+ if (value == 0) {
+ /* timer=0 disables the timer */
+ balloon_stats_destroy_timer(s);
+ return;
+ }
+
+ if (balloon_stats_enabled(s)) {
+ /* timer interval change */
+ s->stats_poll_interval = value;
+ balloon_stats_change_timer(s, value);
+ return;
+ }
+
+ /* create a new timer */
+ g_assert(s->stats_timer == NULL);
+ s->stats_timer = qemu_new_timer_ms(vm_clock, balloon_stats_poll_cb, s);
+ s->stats_poll_interval = value;
+ balloon_stats_change_timer(s, 0);
+}
+
static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
{
VirtIOBalloon *s = to_virtio_balloon(vdev);
@@ -107,9 +234,10 @@ static void virtio_balloon_receive_stats(VirtIODevice
*vdev, VirtQueue *vq)
VirtQueueElement *elem = &s->stats_vq_elem;
VirtIOBalloonStat stat;
size_t offset = 0;
+ qemu_timeval tv;
if (!virtqueue_pop(vq, elem)) {
- return;
+ goto out;
}
/* Initialize the stats to get rid of any stale values. This is only
@@ -128,6 +256,18 @@ static void virtio_balloon_receive_stats(VirtIODevice
*vdev, VirtQueue *vq)
s->stats[tag] = val;
}
s->stats_vq_offset = offset;
+
+ if (qemu_gettimeofday(&tv) < 0) {
+ fprintf(stderr, "warning: %s: failed to get time of day\n", __func__);
+ goto out;
+ }
+
+ s->stats_last_update = tv.tv_sec;
+
+out:
+ if (balloon_stats_enabled(s)) {
+ balloon_stats_change_timer(s, s->stats_poll_interval);
+ }
}
static void virtio_balloon_get_config(VirtIODevice *vdev, uint8_t
*config_data)
@@ -237,6 +377,14 @@ VirtIODevice *virtio_balloon_init(DeviceState *dev)
register_savevm(dev, "virtio-balloon", -1, 1,
virtio_balloon_save, virtio_balloon_load, s);
+ object_property_add(OBJECT(dev), "guest-stats", "guest statistics",
+ balloon_stats_get_all, NULL, NULL, s, NULL);
+
+ object_property_add(OBJECT(dev), "guest-stats-polling-interval", "int",
+ balloon_stats_get_poll_interval,
+ balloon_stats_set_poll_interval,
+ NULL, s, NULL);
+
return &s->vdev;
}
@@ -244,6 +392,7 @@ void virtio_balloon_exit(VirtIODevice *vdev)
{
VirtIOBalloon *s = DO_UPCAST(VirtIOBalloon, vdev, vdev);
+ balloon_stats_destroy_timer(s);
qemu_remove_balloon_handler(s);
unregister_savevm(s->qdev, "virtio-balloon", s);
virtio_cleanup(vdev);