virtio: Add memory statistics reporting to the balloon driver
From: Adam Litke
Date: Mon Nov 09 2009 - 11:32:24 EST
When using ballooning to manage overcommitted memory on a host, a system for
guests to communicate their memory usage to the host can provide information
that will minimize the impact of ballooning on the guests. The current method
employs a daemon running in each guest that communicates memory statistics to a
host daemon at a specified time interval. The host daemon aggregates this
information and inflates and/or deflates balloons according to the level of
host memory pressure. This approach is effective but overly complex since a
daemon must be installed inside each guest and coordinated to communicate with
the host. A simpler approach is to collect memory statistics in the virtio
balloon driver and communicate them to the host via the device config space.
This patch enables the guest-side support by adding stats collection and
reporting to the virtio balloon driver.
Comments?
Signed-off-by: Adam Litke <agl@xxxxxxxxxx>
Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Cc: Anthony Liguori <anthony@xxxxxxxxxxxxx>
Cc: Avi Kivity <avi@xxxxxxxxxx>
Cc: virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index 200c22f..0c9a9a1 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -180,6 +180,41 @@ static void update_balloon_size(struct virtio_balloon *vb)
&actual, sizeof(actual));
}
+static inline void update_stat(struct virtio_device *vdev, int feature,
+ unsigned long value, unsigned offset)
+{
+ __le32 __v = cpu_to_le32(value);
+ if (virtio_has_feature(vdev, feature))
+ vdev->config->set(vdev, offset, &__v, sizeof(__v));
+}
+
+#define K(x) ((x) << (PAGE_SHIFT - 10))
+static void update_balloon_stats(struct virtio_balloon *vb)
+{
+ unsigned long events[NR_VM_EVENT_ITEMS];
+ struct sysinfo i;
+ unsigned off = offsetof(struct virtio_balloon_config, stats);
+
+ all_vm_events(events);
+
+ update_stat(vb->vdev, VIRTIO_BALLOON_F_RPT_SWAP_IN, events[PSWPIN],
+ off + offsetof(struct virtio_balloon_stats, pswapin));
+ update_stat(vb->vdev, VIRTIO_BALLOON_F_RPT_SWAP_OUT, events[PSWPOUT],
+ off + offsetof(struct virtio_balloon_stats, pswapout));
+ update_stat(vb->vdev, VIRTIO_BALLOON_F_RPT_MAJFLT, events[PGMAJFAULT],
+ off + offsetof(struct virtio_balloon_stats, pgmajfault));
+ update_stat(vb->vdev, VIRTIO_BALLOON_F_RPT_MINFLT, events[PGFAULT],
+ off + offsetof(struct virtio_balloon_stats, pgminfault));
+ update_stat(vb->vdev, VIRTIO_BALLOON_F_RPT_ANON,
+ K(global_page_state(NR_ANON_PAGES)),
+ off + offsetof(struct virtio_balloon_stats, panon));
+ si_meminfo(&i);
+ update_stat(vb->vdev, VIRTIO_BALLOON_F_RPT_MEMFREE, K(i.freeram),
+ off + offsetof(struct virtio_balloon_stats, memfree));
+ update_stat(vb->vdev, VIRTIO_BALLOON_F_RPT_MEMTOT, K(i.totalram),
+ off + offsetof(struct virtio_balloon_stats, memtot));
+}
+
static int balloon(void *_vballoon)
{
struct virtio_balloon *vb = _vballoon;
@@ -189,15 +224,17 @@ static int balloon(void *_vballoon)
s64 diff;
try_to_freeze();
- wait_event_interruptible(vb->config_change,
+ wait_event_interruptible_timeout(vb->config_change,
(diff = towards_target(vb)) != 0
|| kthread_should_stop()
- || freezing(current));
+ || freezing(current),
+ VIRTIO_BALLOON_TIMEOUT);
if (diff > 0)
fill_balloon(vb, diff);
else if (diff < 0)
leak_balloon(vb, -diff);
update_balloon_size(vb);
+ update_balloon_stats(vb);
}
return 0;
}
@@ -265,7 +302,12 @@ static void virtballoon_remove(struct virtio_device *vdev)
kfree(vb);
}
-static unsigned int features[] = { VIRTIO_BALLOON_F_MUST_TELL_HOST };
+static unsigned int features[] = {
+ VIRTIO_BALLOON_F_MUST_TELL_HOST, VIRTIO_BALLOON_F_RPT_SWAP_IN,
+ VIRTIO_BALLOON_F_RPT_SWAP_OUT, VIRTIO_BALLOON_F_RPT_ANON,
+ VIRTIO_BALLOON_F_RPT_MAJFLT, VIRTIO_BALLOON_F_RPT_MINFLT,
+ VIRTIO_BALLOON_F_RPT_MEMFREE, VIRTIO_BALLOON_F_RPT_MEMTOT,
+};
static struct virtio_driver virtio_balloon = {
.feature_table = features,
diff --git a/include/linux/virtio_balloon.h b/include/linux/virtio_balloon.h
index 09d7300..0bff4b8 100644
--- a/include/linux/virtio_balloon.h
+++ b/include/linux/virtio_balloon.h
@@ -6,15 +6,39 @@
/* The feature bitmap for virtio balloon */
#define VIRTIO_BALLOON_F_MUST_TELL_HOST 0 /* Tell before reclaiming pages */
+ /* Guest memory statistic reporting */
+#define VIRTIO_BALLOON_F_RPT_SWAP_IN 1 /* Number of pages swapped in */
+#define VIRTIO_BALLOON_F_RPT_SWAP_OUT 2 /* Number of pages swapped out */
+#define VIRTIO_BALLOON_F_RPT_ANON 3 /* Number of anonymous pages in use */
+#define VIRTIO_BALLOON_F_RPT_MAJFLT 4 /* Number of major faults */
+#define VIRTIO_BALLOON_F_RPT_MINFLT 5 /* Number of minor faults */
+#define VIRTIO_BALLOON_F_RPT_MEMFREE 6 /* Total amount of free memory */
+#define VIRTIO_BALLOON_F_RPT_MEMTOT 7 /* Total amount of memory */
/* Size of a PFN in the balloon interface. */
#define VIRTIO_BALLOON_PFN_SHIFT 12
+struct virtio_balloon_stats
+{
+ __le32 pswapin; /* pages swapped in */
+ __le32 pswapout; /* pages swapped out */
+ __le32 panon; /* anonymous pages in use (in kb) */
+ __le32 pgmajfault; /* Major page faults */
+ __le32 pgminfault; /* Minor page faults */
+ __le32 memfree; /* Total amount of free memory (in kb) */
+ __le32 memtot; /* Total amount of memory (in kb) */
+};
+
struct virtio_balloon_config
{
/* Number of pages host wants Guest to give up. */
__le32 num_pages;
/* Number of pages we've actually got in balloon. */
__le32 actual;
+ /* Memory statistics */
+ struct virtio_balloon_stats stats;
};
+
+#define VIRTIO_BALLOON_TIMEOUT (30 * HZ)
+
#endif /* _LINUX_VIRTIO_BALLOON_H */
--
Thanks,
Adam
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