virtio: Add memory statistics reporting to the balloon driver (V4)
Changes since V3:
- Do not do endian conversions as they will be done in the host
- Report stats that reference a quantity of memory in bytes
- Minor coding style updates
Changes since V2:
- Increase stat field size to 64 bits
- Report all sizes in kb (not pages)
- Drop anon_pages stat and fix endianness conversion
Changes since V1:
- Use a virtqueue instead of the device config space
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 directly to the hypervisor.
This patch enables the guest-side support by adding stats collection and
reporting to the virtio balloon driver.
Signed-off-by: Adam Litke <agl@us.ibm.com>
Cc: Anthony Liguori <anthony@codemonkey.ws>
Cc: virtualization@lists.linux-foundation.org
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (minor fixes)
diff --git a/include/linux/virtio_balloon.h b/include/linux/virtio_balloon.h
index 1418f04..a50ecd1 100644
--- a/include/linux/virtio_balloon.h
+++ b/include/linux/virtio_balloon.h
@@ -7,6 +7,7 @@
/* The feature bitmap for virtio balloon */
#define VIRTIO_BALLOON_F_MUST_TELL_HOST 0 /* Tell before reclaiming pages */
+#define VIRTIO_BALLOON_F_STATS_VQ 1 /* Memory Stats virtqueue */
/* Size of a PFN in the balloon interface. */
#define VIRTIO_BALLOON_PFN_SHIFT 12
@@ -18,4 +19,18 @@
/* Number of pages we've actually got in balloon. */
__le32 actual;
};
+
+#define VIRTIO_BALLOON_S_SWAP_IN 0 /* Amount of memory swapped in */
+#define VIRTIO_BALLOON_S_SWAP_OUT 1 /* Amount of memory swapped out */
+#define VIRTIO_BALLOON_S_MAJFLT 2 /* Number of major faults */
+#define VIRTIO_BALLOON_S_MINFLT 3 /* Number of minor faults */
+#define VIRTIO_BALLOON_S_MEMFREE 4 /* Total amount of free memory */
+#define VIRTIO_BALLOON_S_MEMTOT 5 /* Total amount of memory */
+#define VIRTIO_BALLOON_S_NR 6
+
+struct virtio_balloon_stat {
+ u16 tag;
+ u64 val;
+} __attribute__((packed));
+
#endif /* _LINUX_VIRTIO_BALLOON_H */