virtio_balloon: include disk/file caches memory statistics

Add a new field VIRTIO_BALLOON_S_CACHES to virtio_balloon memory
statistics protocol. The value represents all disk/file caches.

In this case it corresponds to the sum of values
Buffers+Cached+SwapCached from /proc/meminfo.

Signed-off-by: Tomáš Golembiovský <tgolembi@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index a1fb52c..dfe5684 100644 (file)
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -257,11 +257,13 @@ static unsigned int update_balloon_stats(struct virtio_balloon *vb)
        struct sysinfo i;
        unsigned int idx = 0;
        long available;
+       unsigned long caches;
 
        all_vm_events(events);
        si_meminfo(&i);
 
        available = si_mem_available();
+       caches = global_node_page_state(NR_FILE_PAGES);
 
 #ifdef CONFIG_VM_EVENT_COUNTERS
        update_stat(vb, idx++, VIRTIO_BALLOON_S_SWAP_IN,
@@ -277,6 +279,8 @@ static unsigned int update_balloon_stats(struct virtio_balloon *vb)
                                pages_to_bytes(i.totalram));
        update_stat(vb, idx++, VIRTIO_BALLOON_S_AVAIL,
                                pages_to_bytes(available));
+       update_stat(vb, idx++, VIRTIO_BALLOON_S_CACHES,
+                               pages_to_bytes(caches));
 
        return idx;
 }

diff --git a/include/uapi/linux/virtio_balloon.h b/include/uapi/linux/virtio_balloon.h
index 343d7dd..4e8b830 100644 (file)
--- a/include/uapi/linux/virtio_balloon.h
+++ b/include/uapi/linux/virtio_balloon.h
@@ -52,7 +52,8 @@ struct virtio_balloon_config {
 #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_AVAIL    6   /* Available memory as in /proc */
-#define VIRTIO_BALLOON_S_NR       7
+#define VIRTIO_BALLOON_S_CACHES   7   /* Disk caches */
+#define VIRTIO_BALLOON_S_NR       8
 
 /*
  * Memory statistics structure.