Commit 7e6ccd9c authored by Luiz Capitulino's avatar Luiz Capitulino
Browse files

balloon: re-enable balloon stats 



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: default avatarLuiz Capitulino <lcapitulino@redhat.com>
Reviewed-by: default avatarEric Blake <eblake@redhat.com>
parent 01ceb97e

hw/virtio-balloon.c

+150 −1
Original line number Diff line number Diff line
@@ -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);