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Subject: [PATCH v1 3/4] virtio-balloon: add a timer to limit the free page report wating time
This patch adds a timer to limit the time that the host waits for the
free pages reported by the guest. Users can specify the time in ms via
"free-page-wait-time" command line option. If a user doesn't specify a
time, the host waits till the guest finishes reporting all the free
pages. The policy (wait for all the free pages to be reported or use a
time limit) is determined by the orchestration layer.
Signed-off-by: Wei Wang <wei.w.wang@intel.com>
CC: Michael S. Tsirkin <mst@redhat.com>
---
hw/virtio/virtio-balloon.c | 85 +++++++++++++++++++++++++++++++++++++-
hw/virtio/virtio-pci.c | 3 ++
include/hw/virtio/virtio-balloon.h | 4 ++
3 files changed, 91 insertions(+), 1 deletion(-)
diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
index a2a5536..dcc8cb3 100644
--- a/hw/virtio/virtio-balloon.c
+++ b/hw/virtio/virtio-balloon.c
@@ -213,6 +213,66 @@ static void balloon_stats_set_poll_interval(Object *obj, Visitor *v,
balloon_stats_change_timer(s, 0);
}
+static void balloon_free_page_change_timer(VirtIOBalloon *s, int64_t ms)
+{
+ timer_mod(s->free_page_timer,
+ qemu_clock_get_ms(QEMU_CLOCK_REALTIME) + ms);
+}
+
+static void balloon_stop_free_page_report(void *opaque)
+{
+ VirtIOBalloon *dev = opaque;
+ VirtIODevice *vdev = VIRTIO_DEVICE(dev);
+
+ timer_del(dev->free_page_timer);
+ timer_free(dev->free_page_timer);
+ dev->free_page_timer = NULL;
+
+ if (atomic_read(&dev->free_page_report_status) ==
+ FREE_PAGE_REPORT_S_IN_PROGRESS) {
+ dev->host_stop_free_page = true;
+ virtio_notify_config(vdev);
+ }
+}
+
+static void balloon_free_page_get_wait_time(Object *obj, Visitor *v,
+ const char *name, void *opaque,
+ Error **errp)
+{
+ VirtIOBalloon *s = opaque;
+
+ visit_type_int(v, name, &s->free_page_wait_time, errp);
+}
+
+static void balloon_free_page_set_wait_time(Object *obj, Visitor *v,
+ const char *name, void *opaque,
+ Error **errp)
+{
+ VirtIOBalloon *s = opaque;
+ Error *local_err = NULL;
+ int64_t value;
+
+ visit_type_int(v, name, &value, &local_err);
+ if (local_err) {
+ error_propagate(errp, local_err);
+ return;
+ }
+ if (value < 0) {
+ error_setg(errp, "free page wait time must be greater than zero");
+ return;
+ }
+
+ if (value > UINT32_MAX) {
+ error_setg(errp, "free page wait time value is too big");
+ return;
+ }
+
+ s->free_page_wait_time = value;
+ g_assert(s->free_page_timer == NULL);
+ s->free_page_timer = timer_new_ms(QEMU_CLOCK_REALTIME,
+ balloon_stop_free_page_report, s);
+}
+
static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
{
VirtIOBalloon *s = VIRTIO_BALLOON(vdev);
@@ -332,6 +392,7 @@ static void virtio_balloon_handle_free_pages(VirtIODevice *vdev, VirtQueue *vq)
atomic_set(&dev->free_page_report_status,
FREE_PAGE_REPORT_S_IN_PROGRESS);
} else {
+ dev->host_stop_free_page = false;
atomic_set(&dev->free_page_report_status,
FREE_PAGE_REPORT_S_STOP);
}
@@ -386,6 +447,10 @@ static void virtio_balloon_free_page_stop(void *opaque)
return;
}
+ if (dev->free_page_wait_time) {
+ balloon_free_page_change_timer(dev, dev->free_page_wait_time);
+ }
+
/* Wait till a stop sign is received from the guest */
while (atomic_read(&dev->free_page_report_status) !=
FREE_PAGE_REPORT_S_STOP)
@@ -399,7 +464,19 @@ static void virtio_balloon_get_config(VirtIODevice *vdev, uint8_t *config_data)
config.num_pages = cpu_to_le32(dev->num_pages);
config.actual = cpu_to_le32(dev->actual);
- config.free_page_report_cmd_id = cpu_to_le32(dev->free_page_report_cmd_id);
+ if (dev->host_stop_free_page) {
+ /*
+ * Host is actively requesting to stop the free page report, send the
+ * stop sign to the guest. This happens when the migration thread has
+ * reached the phase to send pages to the destination while the guest
+ * hasn't done the reporting.
+ */
+ config.free_page_report_cmd_id =
+ VIRTIO_BALLOON_FREE_PAGE_REPORT_STOP_ID;
+ } else {
+ config.free_page_report_cmd_id =
+ cpu_to_le32(dev->free_page_report_cmd_id);
+ }
trace_virtio_balloon_get_config(config.num_pages, config.actual);
memcpy(config_data, &config, sizeof(struct virtio_balloon_config));
@@ -526,6 +603,7 @@ static void virtio_balloon_device_realize(DeviceState *dev, Error **errp)
s->free_page_vq = virtio_add_queue(vdev, 128,
virtio_balloon_handle_free_pages);
atomic_set(&s->free_page_report_status, FREE_PAGE_REPORT_S_STOP);
+ s->host_stop_free_page = false;
}
reset_stats(s);
}
@@ -597,6 +675,11 @@ static void virtio_balloon_instance_init(Object *obj)
balloon_stats_get_poll_interval,
balloon_stats_set_poll_interval,
NULL, s, NULL);
+
+ object_property_add(obj, "free-page-wait-time", "int",
+ balloon_free_page_get_wait_time,
+ balloon_free_page_set_wait_time,
+ NULL, s, NULL);
}
static const VMStateDescription vmstate_virtio_balloon = {
diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
index 6c75cca..3345104 100644
--- a/hw/virtio/virtio-pci.c
+++ b/hw/virtio/virtio-pci.c
@@ -2250,6 +2250,9 @@ static void virtio_balloon_pci_instance_init(Object *obj)
object_property_add_alias(obj, "guest-stats-polling-interval",
OBJECT(&dev->vdev),
"guest-stats-polling-interval", &error_abort);
+ object_property_add_alias(obj, "free-page-wait-time",
+ OBJECT(&dev->vdev),
+ "free-page-wait-time", &error_abort);
}
static const TypeInfo virtio_balloon_pci_info = {
diff --git a/include/hw/virtio/virtio-balloon.h b/include/hw/virtio/virtio-balloon.h
index b84b4af..268f7d6 100644
--- a/include/hw/virtio/virtio-balloon.h
+++ b/include/hw/virtio/virtio-balloon.h
@@ -37,6 +37,8 @@ typedef struct virtio_balloon_stat_modern {
typedef struct VirtIOBalloon {
VirtIODevice parent_obj;
VirtQueue *ivq, *dvq, *svq, *free_page_vq;
+ /* The host is requesting the guest to stop free page reporting */
+ bool host_stop_free_page;
uint32_t free_page_report_status;
uint32_t num_pages;
uint32_t actual;
@@ -45,8 +47,10 @@ typedef struct VirtIOBalloon {
VirtQueueElement *stats_vq_elem;
size_t stats_vq_offset;
QEMUTimer *stats_timer;
+ QEMUTimer *free_page_timer;
int64_t stats_last_update;
int64_t stats_poll_interval;
+ int64_t free_page_wait_time;
uint32_t host_features;
} VirtIOBalloon;
--
1.8.3.1
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